Copyright ©1998 by the authors and the BJCP
Since the inception of the BJCP, several tools have been developed to help potential judges study for the exam. The most widely used are the study guides written by Chuck Cox and Greg Walz. The former was assembled in the early 1990s with the help of readers of the Judge Digest and consists of an outline of the information and terminology needed to pass the exam. The latter is a more verbose discussion of ingredients, brewing procedures and flavors as they relate to beer styles and judging. The outline version is valuable because it encourages independent study; however the verbose version was used as the foundation for the first BJCP Study Guide because information could be added and updated without radically changing the presentation format.
This new edition of the BJCP Study Guide was written with a different approach that was motivated by the feedback and performance from those who have used other study guides. Most of these contain information that is outdated, incorrect or irrelevant to the types of questions asked on the exam. For example, a study guide should not be a tutorial on homebrewing, but should summarize the aspects of the brewing process that relate to beer flavors and styles. The information presented here was written by a group of technically proficient judges and brewers and tailored to the actual BJCP exam questions. The backgrounds of these authors are summarized at the end of the guide. The material has also been reviewed by the BJCP Exam Committee to ensure that it is technically correct and understandable. The goal was to prepare a document that is not only valuable in studying for the exam, but concise and complete enough to be used as a judging handbook. In addition, it is essential that this study guide be made freely available to potential judges. It is available for downloading in several formats on the BJCP Web Page , and free hard copies will be mailed to potential judges upon request.
The study guide begins with a section describing the BJCP and the motivation and mechanics behind the judging process. Also included are BJCP scoresheets, a comprehensive list of possible exam questions and an outline of a study course for beer judges. The second section contains the 1998 BJCP Style Guidelines. Other study guides feature more complete style descriptions, but we found that many potential judges relied on that information as their sole reference for information about beer styles. This may be sufficient to pass the exam, but is no substitute for the wealth of information that is found in Michael Jackson's Beer Companion and The New World Guide to Beer, for example. By just including the style guidelines, the reader is forced to do some independent study to further his or her knowledge of beer styles. The last major section of the study guide is a review of technical information about the brewing process and flavors in beer. Although this material was written with the exam questions in mind, it is no substitute for gaining an understanding of the brewing process by reading the references and putting that knowledge to practical use by actually brewing a batch of beer.
We hope that this study guide fulfills its goal of offering a complete,
concise and understandable overview of the information needed to pass the exam.
We recommend that it be used in conjunction with the following references to
gain a complete understanding of beer styles, beer flavors and the brewing
process. Good luck!
Product evaluation is an important part of brewing, whether performed informally or formally and whether the product is from a commercial or home brewery. Formal beer evaluation serves three primary purposes in the context of brewing competitions. First, the beer evaluations provide feedback to the brewer concerning how well an individual recipe represents its intended beer style. This feedback can be useful as recipes are fine-tuned and attempts are made to improve the beer. Second, beer evaluations may provide brewers with troubleshooting advice. These diagnostic suggestions are particularly helpful when the brewer cannot identify the source of off-flavors or aromas. A knowledgeable beer evaluator can provide the brewer with suggestions for changing procedures and equipment that can help eliminate undesirable flavor and aroma components. Third, beer evaluation provides a fairly unbiased method for selecting and recognizing outstanding beers in brewing competitions.
One important condition that is necessary for accurate beer evaluation is the establishment of a suitable environment. The environment should be well- lit, odor-free, and distractions should be minimized. Natural, diffuse lighting is best, with incandescent lighting preferred over fluorescent lighting. Table cloths and walls should be free of patterns that might obscure visual inspection of the beer, and light colored or white walls and tablecloths are ideal. The room in which evaluation takes place should be as free of odors as possible. Restaurants and breweries can be particularly troublesome locations for evaluating beers because food and brewing odors are likely to interfere with a beer judge's ability to smell the beers being evaluated. Smoking and perfumes should also be eliminated as much as possible. In addition, the evaluation environment should be as free from other distractions. Noise should be kept to a minimum, and privacy should be preserved to the greatest extent possible. Every effort should be made to make the beer judges comfortable by carefully selecting chairs and tables, monitoring the temperature of the evaluation room, and providing assistance to judges during the evaluation process (e.g., stewards).
A second important condition that is necessary for effective beer evaluation is suitable equipment. That is, judges need sharp mechanical pencils with erasersmechanical so that the aroma of wood does not interfere with detecting beer aromas and erasers so that comments and scores can be changed. Beer judges also need suitable cups for sampling the beerimpeccably clean plastic or glass, odor-free, and clear. Also, judges need access to style guidelines. Tables should be equipped with water and bread or crackers for palate cleansing, buckets and towels for cleaning spills or gushes, bottle openers and cork screws, and coolers and temporary caps for temporary storage of opened bottles.
As for the presentation of beers, two methods are common, each with positive and negative points. One method of presentation permits judges open and pour the beer into their own cups. A second method of presentation requires stewards to pour beer into pitchers, and the beer is transferred from the pitcher into judges' cups. When judges are allowed to pour their own beers, there is some danger that moving bottles to the evaluation table will stir up yeast and that judges' opinions of a beer's quality will be influenced by the appearance of the bottles that it comes in. On the other hand, when judges transfer beer from a pitcher, it is more difficult to capture many of the fleeting aromas that might dissipate between the time the bottle is opened and the time that judges are presented with the beer. Another problem with using pitchers is that it is more difficult to temporarily store beer samples so that judges can taste them again at a later time.
There are two general decision making strategies that judges use when evaluating a beer. In a top-down decision making strategy, the judge forms an overall impression about the quality of the beer, decides what overall score to assign that beer, and deducts points for each deficient characteristic of the beer based on the overall impression. The problem with this top-down approach to beer evaluation is that it is difficult to ensure that the points allocated to each subcategory (e.g., aroma, appearance, flavor, body) agree with the comments that were made about that feature of the beer. In a bottom-up decision making strategy, the judge scores each subcategory of the beer, deducting points for each deficient characteristic. The overall score is determined by summing the points for each subcategory. The problem with this bottom-up approach to beer evaluation is that it easy to arrive at an overall score for the beer that does not agree with the overall impression of the beer. In short, judges who use a top-down approach to judging beers may "miss the trees for the forest," while judges who use a bottom-up approach to judging beers may "miss the forest for the trees."
Most judges use a combination of these two extremes. Regardless of which approach seems more comfortable to an individual beer judge, there are several general guidelines that judges should follow when assigning scores to beers. In the current BJCP scoring systems, each beer is evaluated on a 50- point scale, with 10 points allocated to Bouquet/Aroma, 6 points allocated to Appearance, 19 points allocated to Flavor, 5 points allocated to Body, and 10 points allocated to Drinkability. This scoresheet is presented at the end of this section along with a new version proposed by the BJCP and instructions for judges using this new scoresheet. The new scoresheet retains the 50-point scale, but allocates 12 points for Aroma, 3 for Appearance, 20 for Flavor, 5 for Mouthfeel and 10 for Overall Impression. In addition, there are sliding scales on the bottom right hand corner for rating the stylistic accuracy, technical merit and intangibles of each beer. Potential judges should be familiar with each scoresheet until the new version has been approved for general use.
Overall scores should conform to the descriptions given at the bottom of each scoresheet. Excellent ratings (40-50, or 38-44 on the new scoresheet) should be assigned to beers that are excellent representations of the style. Very Good ratings (30-39 or 30-37) should be assigned to good representations of the style that have only minor flaws. Good ratings (25-29 or 21-29) should be assigned to good representations of the style that have significant flaws. Drinkable ratings (20-24 or 14-20) should be assigned to beers that do not adequately represent the style because of serious flaws. A problem rating (19 or 13) should be assigned to beers that contain flaws that are so serious that the beer is rendered undrinkable. In addition, the new scoresheet reserves the 45-50 range for outstanding beers that are truly world-class.
In general, the best beers at a competition should be assigned scores in the 40+ range, with real evaluations of the beer identifying some characteristics of the beer that make it non-perfect. In reality, there is no "perfect beer," so even the best beers are not assigned a score of 50. When providing feedback about very good beers, it is important to identify ways in which the beer can be improved and mention these characteristics on the score sheet. Any serious flaw or missing aspect of a particular beer style (such as lack of clove character in a Bavarian weizen) generally results in a maximum score around 30. Also, note the cut-off score of 25 (21 on the new) determines if a beer adequately represents a particular style. No beer deserves a score below 19 (13 on the new). Brewers who enter competitions pay money to receive helpful, unbiased evaluations of their beers. There is no need to scar a brewer's esteem with extremely low scores and unhelpful, deprecating remarks. Always look for positive comments to make about a beer, and then let the brewer know what aspects of the beer need attention and how to correct any flaws.
Beers should be evaluated using the following procedure:
When a beer judge smells a beer, the judge is literally inhaling small particles of the beer. The sense of smell works by detecting molecules that are diffused into the air. These molecules are inhaled into the sinus cavity where receptors (olfactory cells) detect and translate the chemical information contained in the molecules into information that the brain can interpret. Several things influence a judge's ability to detect the variety of aromas in beer. First, there are different densities of the receptors found in different people. Hence, some judges may simply be more sensitive to odors than are other judges. Second, the receptor cells can be damaged through exposure to strong substances (e.g., ammonia, nasal drugs), and this damage may take several weeks to heal. Third, changes in the thickness of the mucus that lines the nasal cavity may influence a judge's sensitivity. Any molecules that are detected by the olfactory cells must pass through a mucus lining, so daily changes in the thickness of that lining influences our sensitivity from day to day. The thickness of the lining can be influenced by sickness (e.g., colds), or exposure to a variety of allergens or irritants (e.g., pet dander, dust, smoke, perfume, spicy foods). Therefore, judges need to take into account their current levels of sensitivity, given their health and exposure to substances that could interfere with their sense of smell. Finally, the olfactory cells become desensitized to repeated exposure to the same odors. As a result, a beer judge may be less able to detect subtle aromas as a judging session progresses. One way to remedy this problem is to occasionally take deep inhales of fresh air to flush the nasal cavity. Another way to lessen desensitization to certain odors is to sniff something that has a completely different odor (e.g., sniffing your sleeve) (Eby, 1993; Palamand, 1993).
Regardless of a judge's ability to detect various odors in beer, that ability is useless if the judge cannot use accurately descriptive terms to communicate information to the brewer. Hence, it is important for beer judges to build a vocabulary for describing the variety of odors (and knowledge of the source of those odors). Meilgaard (1993) presents a useful taxonomy of beer-related odors. His organizational scheme categorizes 33 aromas into 9 overall categories (oxidized, sulfury, fatty, phenolic, caramelized, cereal, resinous, aromatic, and sour). Beer judges should make efforts to expand their scent recognition and vocabulary.
The sense of taste is very similar to the sense of smell. Taste is the sense through which the chemical constituents of a solid are detected and information about them is transmitted to the brain. The molecules are detected by four types of taste buds that are on the tongue and throat. Sweetness is detected on the tip of the tongue. Saltiness is detected on the front and sides of the tongue. Sourness is detected on the sides of the tongue toward the back of the mouth. And, bitterness is detected on the back of the tongue near the throat. In addition, sweetness, sourness, and bitterness can be detected on the palate (i.e., roof of the mouth). Since all of these flavors are present in beer, it is important that beer judges completely coat the inside of their mouths with beer when evaluating it and that the beer be swallowed. As is true for the scent receptors in the nose, different people have different densities of taste buds and, thus, have different sensitivities to various flavors. Also, taste buds can be damaged (e.g., being burnt by hot food or through exposure to irritants like spicy foods, smoking, or other chemicals), so a judge's sensitivity may be diminished until tastebuds can regenerate (about 10 days). Judges need to be aware of their own sensitivities and take into account recent potential sources of damage when evaluating beers. In addition, taste buds can be desensitized to certain flavors because of residual traces of other substances in the mouth. Therefore, it is best for judges to rinse their mouths between beers and to cleanse their palates with bread or saltless crackers (Eby, 1993; Palamand, 1993).
Of course, as is true for the sense of smell, a judge's ability to taste substances in beer is useless unless that judge can accurately identify the substance and use appropriate vocabulary to communicate that information to a brewer. Meilgaard's (1993) categorization system for beer flavors includes 6 general categories (fullness, mouthfeel, bitter, salt, sweet, and sour) consisting of 14 flavors that may be present in beer. Judges should continually improve their abilities to detect flavors that are in beer, their abilities to use appropriate words to describe those perceptions, and their knowledge of the sources of those flavors so that brewers can be provided with accurate and informative feedback concerning how to improve recipes and brewing procedures.
There are five things to keep in mind as you write comments about the beers you judge. First, your comments should be as positive as possible. Acknowledge the good aspects of the beer rather than focusing only on the negative characteristics. Not only does this help make any negative comments easier to take as a brewer, but it gives your evaluation more credibility. Second, and related, be polite in everything that you write about a beer. Sarcastic and deprecating remarks should never be made on a score sheet. Third, be descriptive and avoid using ambiguous terms like "nice." Instead, use words to describe the aroma, appearance, and flavors of the beer. Fourth, be diagnostic. Provide the brewer with possible causes for undesirable characteristics, and describe how the recipe or brewing procedure could be adjusted to eliminate those characteristics. Finally, be humble. Do not speculate about things that you do not know (e.g. whether the beer is extract or all-grain), and apologize if you cannot adequately describe (or diagnose) characteristics of the beer that are undesirable.
Before a judging event, you should take steps to mentally and physically prepare yourself. Thoroughly familiarize yourself with the style(s) that you will judge if you know what those styles are ahead of time. Sample a few commercial examples and review the style guidelines and brewing procedures for those styles. Also, come to the event prepared to judge. Bring a mechanical pencil, a bottle opener, a flashlight, and any references that you might need to evaluate the beers. Also, make sure to come to the event in the right frame of mind. Get adequate rest the night before; shower; avoid heavily scented soaps, shampoos, and perfumes; avoid eating spicy foods and drinking excessively; and avoid taking medication that might influence your ability to judge (e.g., decongestants). You can also prepare your stomach for a day of beer drinking by drinking plenty of water and eating a dinner that contains foods that contain fats the night before the event and by eating extra sugar the morning of the event (e.g., donuts) (Harper, 1997).
During a judging flight, it is important to keep in mind that errors can creep into your judging decisions as a result of fatigue (palate or physical), distractions, or the order in which beers are presented. More specifically, judges may tend to assign scores (central scoring) in a much narrower range as time progresses simply because palate fatigue causes the beers to taste more and more similar over time. Conversely, judges may assign one or two beers much higher scores than other beers simply because they stand out as being much more flavorful (extreme scoring). In addition, as judges become tired (and possibly intoxicated) during long flights, they may allow impressions of some very noticeable characteristics of particular beers to overly influence their perceptions (and scores) of other characteristics of the beers (halo effect). For example, a weizen that is too dark may (falsely) also seem too heavy and caramel-flavored. Also during long flights, judges need to be mindful of the fact that proximity errors (e.g., assigning scores that are too high to a beer that follows a poor example of the style) and drift (e.g., assigning progressively lower (or higher) scores to beers as time progresses) may influence the validity of the scores that they assign (Wolfe, 1996; Wolfe & Wolfe, 1997).
Unfortunately, it is nearly impossible to know when errors such as these have crept into your judgments. Therefore, it is extremely important to retaste all of the beers in a flight, especially the ones in the top half of the flight. In general, most flights should contain less than 12 beers, so this would entail retasting at least the 6 that receive the highest scores. Each beer should be carefully reevaluated to make sure that the rank ordering of the assigned scores reflects your overall impression of the actual quality of the beers. Only after retasting and discussion of these impressions should awards be assigned to beers within the flight. Note that the competition coordinator may request that you readjust your scores to reflect any discrepancies between the ordering of awards and the ordering of assigned scores.
When you have finished judging a flight of beers, make sure that your score sheets are complete, that the score sheets have been organized in a way that the competition organizer can identify the scores and the awards that you assigned, and that the table at which you judged is ready to for another judging flight or that (following the final flight of the day) it is cleaned. Most importantly, avoid causing distractions to other judges who have not yet finished judging their flights (e.g., loud conversations, interrupting judges who are still making decisions, etc.). In fact, this would be a good time to leave the judging area for a beer or a breath of fresh air. Also, be conscientious in what you say to others about the beers that you judged. It is often tempting to tell others about the worst beer in your flight or to make remarks about the overall poor quality of entries that you judged. Not only are comments such as these in poor taste, but since you do not know who entered the beers that you judged, you may offend the person to whom you are talking (or judges who are still judging).
Of course, one of the best (and most enjoyable) things that you can do to maintain your judging skills is to continually practice by sampling a variety of beers and brewing your own beers. In addition to visiting pubs and microbreweries, you can sample homebrew regularly by attending homebrew club meetings. Entering beers in competitions is also a practical way to compare your flavor perception and troubleshooting skills with those of experienced judges. You can also brush up on your judging skills by coordinate tasting sessions and mini-competitions with other judges or by sampling beers that have been "doctored" to simulate common flavors and flaws in beer (Wolfe & Leith, 1997). Dr. Beer ® is a commercial example of this program, but several authors have described methods for preparing beers using readily- available ingredients (Guinard & Robertson, 1993; Papazian & Noonan, 1993; Papazian, 1993). Guidelines for a doctored beer session are also given at the end of the BJCP Exam Study Course later in this section.
These will be added as soon as HTML versions are available. They are included
with hard copies of this study guide.
The BJCP exam is closed book and consists of an essay portion worth 70 percent and a tasting portion worth 30 percent of the total score. On the essay portion, there are ten questions covering beer styles and brewing techniques, with the latter focusing on the relationship of ingredients and the brewing process to flavors in the finished beer. The style questions typically ask for descriptions and comparisons of related beer styles, including information on the historical development, ingredients, style parameters, commercial examples and the brewing process. See the following two sections for a list of the BJCP exam questions and an example of an answer with enough content and depth to receive a very high mark. In addition to style and technical questions, since judges represent the BJCP, part of one question asks for a brief description of the purpose and levels of judging program. It should be noted that although the current exams are formed from a large pool of essay questions, the BJCP exam committee is currently investigating the feasibility of replacing some of these with short-answer or multiple choice questions.
The exam is criteria-based, so if the essay questions are not answered correctly or do not contain enough information (a good rule of thumb is one page per answer), then it will be difficult to get a passing score on the written portion. Similarly, if the descriptions and feedback on the beer scoresheets are weak, it will be difficult to pass the tasting portion. The recommended materials should therefore be read before the study sessions and reviewed along with the BJCP Study Guide before the exam. The style categories in the questions below are based on the BJCP Guidelines, but those used by the AHA for its national homebrew competition are also acceptable. The exam questions are written and graded in a manner which is independent of which particular style guidelines is used as a reference.
The tasting portion of the BJCP exam requires the judging of four beers as if one were at a competition, with the scoresheets evaluated on the basis on scoring accuracy, perception, descriptive ability, feedback and completeness. Grading is done by volunteer National and Master judges, with their scores and feedback reviewed by both an associate exam director and the exam director. These reviews ensure that the scores from different exams and graders are consistent between different exams and with the criteria expected for the different judging levels.
Q: Describe and differentiate Abbey and Trappist beers. Give commercial examples of each.
A: The primary difference between Abbey and Trappist beers is that the latter is an appellation which restricts its production to the six Trappist monasteries in the Low Countries. They are Chimay, Orval, Rochefort, Westmalle and Westvleteren in Belgium and Schaapskooi in the Netherlands. Abbey beers on the other hand, are either brewed at non-Trappist monasteries or by commercial breweries to which abbies have licensed their names. Commercial examples of these include Affligem, Leffe and Grimbergen.
Both Abbey and Trappist breweries are best known for the dubbel and tripel styles. The former is a tawny beer with an OG in the 1.060-70 range, 6-8% alcohol, and enough bitterness to balance, approximately 20-25 IBUs. The color is generally deep ruby to brown and derived from both Belgian specialty malts and caramelized candi sugar. The flavor is dominated by a full-bodied malty sweetness reminiscent of plums, raisins and black currents. Ester levels are generally subdued by Belgian standards, but some examples do have moderate bubble-gum or banana esters. Tripels, on the other hand, are much paler in color at 3-5 SRM, but have higher OG (1.070-90) and alcohol levels (7-10 %). The malts used are almost entirely pilsner, with light candi sugar used to increase the alcohol content and prevent the beer from being too cloying. Hop rates are again moderate at 25-30 IBUs, with some noble hop flavor and aroma acceptable. The ester levels are often more assertive in this style, though the increased alcohol content should be subtle. Westmalle Dubbel and Tripel are classic examples of these styles.
Some Trappist breweries also produce beers which would better fit into the strong ale category due to high ester levels or unusual brewing procedures. In the latter category are Chimay (Premiere, Cinq Cents and Grand Reserve) and Rochefort (6, 8 and 10) brews, which have very distinctive signatures from the yeast. One of the most unusual beers in Belgium is made by Orval, the only beer brewed by that monastery. It has a moderate gravity in the 1.055-60 range, is dry hopped with East Kent Goldings and primed with a mixture of five yeast strains that includes Brettanomyces. As the beer ages, the flavors become more complex, picking up leathery/oaky and even phenolic notes from the yeast.
The ten session course outlined below is a modification of ones that have been effective in preparing judges for the BJCP exam. One or two members of the study group are usually assigned to the task of collecting commercial and homebrewed examples of a given style. They should also prepare and distribute handouts that outline the background and characteristics of each style, as well as a technical topic relevant to the exam. All but one of the beers are then served blindly and discussed, with positive and negative attributes identified. After the tasting session, a technical topic concerning ingredients, the brewing process, or beer flavors is reviewed. Finally, the study group takes a mini-exam that consists of two essay questions taken from the BJCP question pool and judges the remaining beer using the BJCP beer scoresheet. The exam questions should be correlated with the style and technical information that was presented in the class, and there should be forty minute time limit that is well-matched to the three hours required for the actual exam. The total time for each class should be approximately three to four hours, depending on the number of commercial examples and depth of the presentations and discussions.
It should also be easy to persuade local beer experts to participate in the review sessions (bribery with free beer is very effective), but the work can also be divided among those studying for the exam. The commercial examples below are based on beers which are available in the Mid-Atlantic, but a similar collection can be assembled in other geographic areas. The number of beers served in each class should be limited to 8-10, depending on the alcoholic strength and sample size, to prevent palate fatigue and promote responsible drinking. It is also recommended that a flat fee be charged for the class, payable in advance or at the first study session. The Brewers United for Real Potables homebrew club set this fee at $50 for its most recent study course, and while this did not quite cover the actual expenses, the club gladly covered the remainder due to the intangible benefits of having an educated membership. This amount may seem a bit steep from the perspective of the participants, but keep in mind that they are tasting as many as one hundred commercial examples and picking up invaluable information about beers styles and the brewing process.
Flavor: Adulterant, Quantity.
The material in these classes can be comfortable covered in a time frame of
three to five months, depending on the needs and experience of the study group.
Shorter courses have the advantage of keeping the material fresh, while longer
courses allow more intensive reading and reviewing in between classes. Note that
the lead time required to schedule a BJCP exam is approximately three months, so
keep this in mind when planning the study sessions. For more information, e-mail
may be sent to the BJCP exam
director.
When beers of similar character are grouped together, the resulting classifications are called "styles." In the BJCP Style Guide, these are called categories. Sub-classifications of similar beers with distinct differences are called sub-categories. Historically, types of beers were a consequence of the local water, ingredients and technology available at the time. In most cases, brewers did not set out to develop a specific "style," or type of beer. For example, the high sulfates in the hard water around Burton-on-Trent resulted in a drier flavor that accentuated the bitterness of well-hopped ales, while the soft water in Pilsen enabled the brewers to produce a pale lager with a high hop bitterness and soft palate that would not be possible with hard water. Thus these classic styles were determined by the water of the region. Style guidelines also make distinctions between similar styles. There are a number of Pilsners brewed in Germany, and although there are variations, they can all be broadly classified in the German Pilsner style, but are sufficiently different from the Bohemian Pilsners to deserve a separate sub-classification in the beer taxonomy.
Beer styles are not static but change over time in history as ingredients, brewing technology and consumer demand change. For example, the IPA described in the style guidelines originated in the UK, but is now rarely brewed due to the high taxes imposed on beers of this strength. History and geography highly impact the development of brewing; it is important that BJCP judges have an understanding of these factors. The examinee should be able to discuss these factors on the exam and use this depth of knowledge when providing feedback to brewers.
The beers documented in the BJCP style guide are those that are most commonly brewed by home brewers in the US. It is not a complete list of all known beers, even those available throughout the world today. This style guide is continually kept up to date as newer information is made available. Its purpose is to provide a definition of the commonly brewed beers which should be used by both the brewer and the judge as criteria against which each style is evaluated. This section and the BJCP style guide is not intended to be the complete source of information for the prospective BJCP judge. It's recommended that the potential judge read and study Michael Jackson's New World Guide to Beer and Beer Companion, the Classic Beer Style Series and other sources of information to obtain a complete understanding of the history, geography, and characteristics of the beers described in the BJCP Style Guide. The BJCP Style Guide, however, should serve as an accurate, quick reference to the different types of beers.
Most of the figures for starting gravity (SG), percent alcohol by volume (v/v), International Bittering Units (IBU) and color (degrees Lovibond or SRM) are taken from one of several sources assimilated by the BJCP Style Guide Committee including:
To receive full credit for beer style questions on the BJCP exam, examinees should provide at least approximate SG and IBU ranges for the style and, where relevant, other parameters such as alcohol content.
It is strongly suggested that the section of this study guide providing sample exam questions pertaining to beer styles be read carefully. These provide an indication of the range and type of questions to expect on the BJCP exam. You will note that not only will you potentially be asked to "describe" styles but also to "differentiate" among them. In this case, it is expected that you will be able to compare the similarities and differences of the indicated styles. In almost all cases, the examinee is expected to provide relatively well known commercial examples of different styles requested on the exam. While the examinee may not have traveled to the respective countries to try local commercial beers or these beers may not be available in your area, it still is expected that you will have a knowledge of the commercial examples from the BJCP Style Guide, Michael Jackson's books and other references.
LAGERS are produced using bottom-fermenting lager yeasts, Saccharomyces uvarum (or S. carlsbergensis). This family of yeasts works well at lower temperatures, generally between 45 and 55 F. This colder fermentation reduces or eliminates the production of esters and other flavor components, generally resulting in a cleaner tasting beer. During the fermentation and lagering process, at temperatures down to approximately 32 F, the lager yeast remains active, continuing to reduce fermentation by-products, resulting in a cleaner, more mellow flavor in the finished beer. Lagers are a relatively new beer style, only produced commercially after the introduction of mechanical refrigeration in the 1800's.ALES are produced using top fermenting ale yeast, Saccharomyces cerevisiae. These strains of yeast works at warmer temperatures and ferment out faster than their lager counterparts. Fermentation byproducts such as fruity, estery flavors are usually evident and make up a significant part of the ale profile. Ale yeast are usually temperature sensitive and will flocculate and become dormant when lagered at cool temperatures for extended periods of time.
MIXED STYLES use one or more variations of temperature and yeasts, such as fermentation with ale yeast at colder temperatures, use of ale and lager yeasts in combination, use of lager yeasts at warmer, ale-like temperature, or use of special yeast strains.
BELGIAN STYLES are generally ales, but with sufficient differences in process and taste profile to warrant their inclusion as a separate style section. Some Belgian styles, such as the Lambics, use a combination of wild yeasts and various bacteria in their fermentation process.
The SPECIALTY, CIDER and MEAD categories should be understood by the potential BJCP judge since s/he will not know in advance which categories s/he may have to judge in an actual competition and a judge should be prepared to judge any category. However they are not required knowledge for the BJCP Exam.
Water constitutes 85-90% of beer, with the remainder being compounds derived from malt, hops and yeast. As a general rule, if it is drinkable, it may be used in brewing, although some adjustments may be needed to mimic the water used in some historical beer styles. Most tap water is also treated with chlorine to inhibit bacterial growth, and this should be removed to produce high-quality beer. Chlorine gas may be eliminated by boiling, but charcoal filtration must be used to eliminate the more commonly used chloroamines. Reverse osmosis is not recommended since it also strips out minerals needed by the yeast. Most water generally also has very low concentrations of nitrogen-containing ions, iron, manganese, copper and zinc; trace amounts of these last four minerals are essential to a healthy fermentation. Finally, most water contains very low concentrations of bacteria, so it must be sterilized by boiling at some point in the brewing process.
Water is a solution of ions with negative (anions) and positive (cations) charges. The water molecules (H2O) themselves are also partially dissociated into hydroxide (OH-) and hydrogen (H+) ions, and the pH, or percent Hydrogen, indicates the relative concentrations of these ions. Neutral water has OH- and H+ concentrations of 0.1 ppm, which corresponds to a pH of 7. Lower pH values indicate a higher H+ concentration and a higher acidity, while higher pH values correspond to a higher OH- concentration and a higher alkalinity. In brewing, the pH is determined by the hardness, alkalinity and buffering salts derived from the ingredients.
Alkalinity is a measure if the capacity of the dissolved anions to neutralize
reductions in the pH value of the solution. The most important anion at the pH
of brewing water and wort is bicarbonate (HCO2-), which
reacts with Calcium (Ca+2) ions when heated to form a calcium
carbonate precipitate and water:
Ca+2 +
2HCO2- = Ca2CO3 (ppt) +
H2O + CO2 (gas)
This removes Calcium ions from the water, reducing the temporary hardness. Permanent hardness is a measure of the cations that remain after boiling and racking the water from the precipitate, and is primarily due to Ca+2 and Magnesium (Mg+2) ions. These cations are permanent of they are derived from sulfate or chloride salts and temporary if they originate in carbonate or bicarbonate salts.
An important process in brewing that helps adjust the pH of the mash is the enzymatic degradation of phytin in the malt to form phytic acid and calcium or magnesium phosphates, which precipitate. Most of the phytic acid combines with free Ca+2 to form more calcium phosphate, releasing hydrogen ions in the process. This reaction generally takes place during the acid rest and regulates the mash pH to the 5.2-5.7 range, which is appropriate for the breakdown of starches and proteins. Some water supplies are too alkaline for this process to be effective, in which case the pH must be reduced to the proper level by adding lactic or sulfuric acid.
The most important cation in brewing is Calcium, which is essential for reducing the mash pH to the appropriate range, keeps oxalate salts in solution (they form haze and gushing if they precipitate), reduces the extraction of tannins, and assists in protein coagulation in the hot and cold breaks. Magnesium ions participate in the same reactions, but are not as effective. Yeasts require 10-20 ppm as a nutrient, but higher amounts give a harsh, mineral-like taste. Another cation is Sodium, which accents the sweetness at low levels, but tastes salty at higher concentrations.
The most important anion in brewing is bicarbonate, which neutralizes acids from dark and roasted malts, reacts with Calcium to reduce the hardness and promotes the extraction of tannins and coloring compounds. It is normally in solution with the carbonate (CO3-2) ion, but the bicarbonate is by far the most important component at typical pH values of water and wort. The sulfate (SO4-2) ion does not play a significant role in the brewing process, but accents hop bitterness and dryness at the high concentrations found in the waters at Burton-on-Trent. Another anion is chloride (Cl-), which enhances sweetness at low concentrations, but high levels can hamper yeast flocculation.
The ions described above are found in different concentrations depending on
the source of the water, as shown in the table below for several major brewing
centers (data from Greg Noonan's water workshop at the 1991 AHA Conference and
are in ppm):
Mineral Calcium Magnesium Sodium Sulfate Bicarbonate Chlorine Pilsen 7 2 2 5 15 5 Dortmund 22 40 60 120 180 60 Munich 75 18 2 10 150 2 Vienna 200 60 8 125 120 12 Burton 275 40 25 450 260 35 Dublin 120 5 12 55 125 20 Edinburgh 120 25 55 140 225 65 London 90 5 15 40 125 20
These water compositions have played an important role in the development of world beer styles. In London, Dublin and Munich, the high bicarbonate content is needed to balance the acidifying properties of the dark and roasted malts used in porters, stouts and bocks. When brewing pale beers with this type of water, the alkalinity generally needs to be reduced through an acid rest, the use of acid malt or directly adding lactic or sulfuric acid to the brewing liquor. The water at Burton is extremely hard, and the high concentrations of sulfate and magnesium ions lend a dryness that accents the hoppiness of English bitters and pale ales from this region. On the other end of the spectrum is Pilsen, which has very low concentrations of dissolved ions (which is not the same as being very soft). The adoption of decoction mashing may have been in part due to the lack of minerals in the water, along with the use of undermodified malts. The elaborate series of temperature steps in a decoction mash helps the various enzymatic reactions proceed at a reasonable rate, even though the enzymes are working slowly due to the lack of calcium.
The waters at these brewing centers may be reproduced by adding various salts to locally available water. For additions meant to improve the buffering capacity of the mash, use the volume of your mash for your calculations. For salt additions to change flavor in the finished beer, the target volume of the finished beer should be used. The most common salt additions are gypsum (CaSO4.2H2O = CaSO4 hydrated with two water molecules), Epsom salts (MgSO4.7H2O), non-iodized table salt (NaCl), calcium carbonate (CaCO3) and calcium chloride (CaCl2). The addition of gypsum and Epsom salts is known as Burtonizing, since it elevates the hardness and sulfate concentrations to levels similar to that found at Burton-on-Trent. Other salts may be used, but these are by far the most common additives in brewing.
Barley is the most common source of the fermentable sugars in beer. The barley kernel is the seed of a plant of the grass family, Gramineae. Barley malt is formed by sprouting barley kernels to a desired length, then stripping off the rootlets and kilning (drying) the kernels to a specific color. These kernels consist of a germ, which is the actual germinating portion, and the endosperm, which is the starch or reserve food source for the germinating embryo. Both are surrounded by the husk, which is almost all cellulose. The acrospire is the portion of the developing plant that will become the above-ground shoot. Growing from the germ, the length of the acrospire has historically been used as an index of malt progress. As germination proceeds, enzymes acting on both proteins and carbohydrates are activated and transformed. The degree of germination is called modification; modification usually refers to the degree to which the protein/gum matrix of the endosperm has been broken down, and the degree to which proteins have become soluble in water.
A variety of measures can be used to indicate the degree of modification of malt. It is important to recognize that while the malting process is designed to initiate enzyme development that will be used to catalyze mashing reactions, the effects of varying malting regimes is dependent on barley strain. While undermodified malts usually have a more complete set of enzymes, they also have more proteins that require additional enzymatic breakdown to avoid protein-polyphenol induced haze (i.e., chill haze). The goal of the maltster is to accomplish the appropriate degree of protein degradation and starch availability, while not allowing too much carbohydrate substrate to be used up in plant development. Thought of another way, the maltster tries to manage desirable malt characteristics while still maximizing the potential yield from the barley.
It has become increasingly difficult to find truly undermodified malt that requires extensive protein rests as part of the mashing schedule. Measured both as a function of soluble Nitrogen (Kolbach Index) and as coarse:fine difference in extract, most modern malts have undergone a high level of protein degradation and most of the formerly bound starch is free in the friable endosperm. While there is no de facto assurance that malt will be suitable for brewing to a particular style, it is beneficial to understand modern barley growing and malting practices.
Two types of barley are commonly used in brewing. They are distinguished by the number of fertile flowers on the heads along the central stem. Two-row barley (Hordeum vulgare) has only two of the six flowers on the head fertile and able to produce kernels. Six row barley has all kernels fertile. An intermediate variety, called four-row, is in fact a six-row variety. It is not widely used in brewing due to the high protein content of the kernels.
Two-row barley will have bigger kernels, and thus higher yield than six-row. It usually has a lower nitrogen and protein content and also has have a lower husk content, which makes 2-row beers taste less grainy. Six row barley, however, generally gives more yield per acre and has a higher diastatic power (more enzymes), so it is the choice whenever large amounts of adjuncts are used. The extra husk content of six-row also aids in providing a lautering filterbed.
The process of malting is done to convert the large, insoluble starch chains of the endosperm to water-soluble starches, and to activate both the proteolytic and diastatic enzymes that will reduce the proteins and starches into desirable components in the mash. The most important enzymes for malting are debranching enzymes, which break 1-6 links in alpha-glucans, and beta- amylase, which produces maltose units by breaking 1-4 links near reducing ends. During the germination phase, the cell walls are broken down by the cytase enzyme complex, which includes hemicellulases and the beta-glucanases. This clears a path for other enzymes into the endosperm so that degradation can proceed more easily.
Malting is basically sprouting the grains to a desired modification. The acrospire grows from the germ end of the corn to the opposite end. The ratio of the acrospire length to the length is the degree of modification, expressed as a percent or ratio. A ratio of 1.0 is indicative of fully- modified malt. Such a malt will be low in protein content and will have the endosperm almost fully converted to water-soluble gum. However, the starch content and potential yield will be reduced through its consumption during the growth of the acrospire and the rootlets.
American and Continental malts are generally less modified. Continental malt is modified only to 50-75%, which retains more of the endosperm for fermentability and creates greater nitrogen complexity, but at the price of reduced enzyme activity. American six-row is also modified to between 50-75%, but the higher protein and nitrogen content of six-row gives greater enzyme strength. Both Continental and American malts require a protein rest (at ~122 F) to degrade the albuminous proteins into fractions that can be both used to promote yeast growth and give good head retention.
The barley is steeped in 50-65 F water for about two or three days, then allowed to germinate for six to ten days between 50 and 70 F. The acrospire will usually grow to 50% at about the sixth day of germination. At the end of germination, the malt is gradually raised in temperature to 90 F, held there for 24 hours to permit enzyme action, then gradually raised to 120 F. It is held at this temperature for 12 hours to dry the malt, as it is essential that the malt be bone-dry before being heated to kilning temperatures to prevent the destruction of the enzymes.
Kilning, or roasting the malt, combined with the degree of modification, determines the type and character of the grain. Vienna malts are low-kilned at around 145 F, British and American pale malts at between 130 and 180 F and Czech malts are raised slowly from 120 to 170 F to dry, then roasted at 178 F. Dortmund and Munich malts are first kilned at low temperatures before the malt has dried, then the temperature is slowly raised to 195-205 F for Dortmunder malt, and 210 to 244 F for Munich malt. This process creates flavor and body-building melanoidins from amino acids and malt sugars. Amber malt is well-modified, and then dried and rapidly heated to 200 F. The temperature is then raised to 280-300 F and held there until the desired color is reached.
Crystal and caramel malts are fully modified, then kilned at 50% moisture content. The temperature is raised to 150-170 F and held for 1 1/2 to 2 hours. This essentially mashes the starches into sugars inside the grain husk. The malt is then heated to the final roasting temperature, with the time and temperature determining the Lovibond color index.
Chocolate and Black Patent malts are undermodified (less than 1/2), dried to 5% moisture, then roasted at 420-450 F for up to two hours, depending on the degree of roastiness desired. The high heat helps degrade the starches, so no protein rest is require for these malts even though they are not fully modified. Malts kilned over smoky beechwood fires, as in Bamberg, pick up a rich, heavy smokiness (which is imparted to the beer) from the phenols in the smoke. Whiskey malt is made in a similar manner by smoking over peat fires.
Kilning at the maximum temperature is generally done only until the grains are evenly roasted. They are then cooled to below 100 F and the rootlets removed. Malts should be allowed to rest for a month or so before being mashed.
The most widely used malted grain besides barley is wheat, which is a key ingredient in German and American wheat beers and used in small quantities in others to improve head retention. It has sufficient diastatic power to breakdown its own proteins and starches, but since it does not have a husk, it is usually mashed with barley malt in order for an adequate filter bed to be formed during the lautering stage. The protein and beta-glucan content of wheat is high compared to barley, so a more extensive mash schedule with an extended protein rest may be needed when large quantities are used. Other malted grains used in brewing include rye, oats and sorghum, but these are more commonly used in their raw forms.
The barley corn contains sugars, starches, enzymes, proteins, tannins, cellulose, and nitrogenous compounds for the most part. The starches will be converted into simple and complex sugars by diastatic enzymes during the mash. Proteins in the kernel serve as food for the germ. These are primarily reduced by proteolytic enzymes into polypeptides, peptides and amino acids. Since enzymes are proteins, the protein content of the malt is an indication of its enzymatic strength. Peptides of the B-complex vitamins are also present and necessary for yeast development. The phosphates in the malt are responsible for the acidification of the mash and are used by the yeast along with other trace elements during the fermentation.
Cellulose, polyphenols and tannins are present in the husk and can lead to harsh flavors in the finished beer if they are leached out by hot or alkaline sparge water. Fatty acids and lipids support respiration of the embryo during malting, but oxidative off flavors and low head retention may result if excessive levels are carried into the wort. Hemicellulose and soluble gums are predominantly polysaccharide in nature and for about 10% of the corn weight. The gums are soluble, but the hemicellulose must be reduced by the appropriate enzymes into fractions that permit good head retention, otherwise they may cause clarity problems in the finished beer.
Unmalted cereal grains have been introduced into brewing because they offer a cheap source of carbohydrates and tend to make a minimal contribution to the wort protein level. They can therefore be used in conjunction with high- protein malts such as American 6-row to give a more fermentable wort and a less filling beer. The starches must be gelatinized before mashing, either by doing a preliminary boil in the double-mash procedure or by flaking them through hot rollers. The most common cereal grains are corn (flaked maize, refined corn grits, corn starch or corn grits), rice grits, sorghum (in Africa), flaked barley, flaked rye and wheat (hard red winter wheat or flaked wheat). The corn and rice adjuncts are used heavily in the American light lager styles, while raw wheat is a key ingredient in Belgian white and lambic beers.
An adjunct is defined as any unmalted source of fermentables in brewing. These include corn and cane sugars, which provide a cheap source of sugar, but are fully fermentable and tend to yield more alcohol and dry out the beer. The enzymes excreted by the yeast to metabolize the sucrose in cane sugar can also give a cidery flavor. Honey is a common adjunct in specialty beers, and although it contributes some aromatics, the high sugar content tends to make a beer thinner and more alcoholic than its all-malt counterpart. To achieve a fuller palate, malto-dextrin syrup or powder may be used, but the dextrin content may also be increased by adjusting the malt bill or mashing procedure. Finally, adjuncts that add color, flavor and fermentables include caramel, molasses, maple syrup and licorice.
Beer color is determined by the types of malts used, and is an important characteristic of any style. Two scales are used for color determination - the EBC scale used in Europe, and the SRM scale in the USA. Both scales go from low to high, with low numbers referring to lighter colors. For example, an American light lager would be around 2-4 SRM, a Pilsner between 3-5, an Oktoberfest in the 5-14 range, and a Doppelbock in the 20-30 range. Some stouts can be over 60 degrees in color and are essentially opaque. The beer color is primarily determined by the malt, but factors such as the intensity and length of the boil also play a role. For a detailed discussion of beer color, the reader is referred to Ray Daniels' three-part series on beer color that begins in the July/August, 1995 issue of Brewing Techniques.
The primary goal of mashing is to complete the breakdown of proteins and starches that was begun during the malting process. This is accomplished by several groups of enzymes that degrade different substrates during a series of rests at specific temperatures.
With pale lager malts, this enzymatic degradation begins with the acid rest, where phytase breaks down phytin into calcium- and magnesium-phosphate and phytic acid. This helps acidify the mash when the brewing water has a low calcium content and roasted grains are not part of the grist. This rest occurs at temperatures in the 95-120 F range. Another group of active enzyme in this range are the beta-glucanases, which break down hemicellulose and gums in the cell walls of undermodified malts. Some adjuncts, particularly rye, have high levels of these substances, and stuck mashes or other problems can result if they are not degraded to simpler substances by the beta-glucanases.
For most malts, the mash begins with the protein rest, which is normally carried out at temperatures in the 113-127 F range. This process begins with the proteinases, which break down high molecular weight proteins into smaller fractions such as polypeptides. These polypeptides are further degraded by peptidase enzymes into peptides and amino acids, which are essential for proper yeast growth and development. Proteins of molecular weight 17,000 to 150,000 must be reduced to polypeptides of molecular weight 500-12,000 for good head formation, and some of these further reduced to the 400-1500 level for proper yeast nutrition.
The final enzymatic process involves the conversion of starches into dextrins and fermentable sugars. The starches must be gelatinized for this to take place, and this occurs at temperatures of 130-150 F for barley malt. The gelatinization temperature is higher for raw grains, such as corn grits, so these adjuncts must be boiled or hot-flaked before adding to the mash. The breakdown of starches is carried out by the combined action of debranching, alpha-amylase and beta-amylase enzymes during the saccharification rest. Debranching enzymes break the 1-6 links in starches, reducing the average length and complexity of the molecules. The diastatic, or amylase, enzymes work in tandem, with the beta-fraction breaking off maltose units from reducing ends and the alpha-fraction breaking 1-4 links at random. Temperatures below 150 F favor beta-amylase, producing a more fermentable wort, while temperatures above 155 F favor alpha-amylase, producing a more dextrinous wort.
The simplest sugars produced in the manner are monosaccharides, with only one basic sugar structure in the molecule. Monosaccharides in wort include glucose, fructose, mannose and galactose. Disaccharides are made up of two monosaccharides coupled together, and include maltose, isomaltose, fructose, melibiose, and lactose. Trisaccharides (three monosaccharides) include maltotriose, which is slowly fermentable and sustains the yeast during lagering. Oligosaccharides constructed of glucose chains (many monosaccharides joined together), are water soluble and called dextrins. The relative concentrations of these sugars are determined by the types of malt and whether the mash schedule favors alpha-amylase or beta-amylase activity.
After this phase is completed, many brewers mash-out by raising the temperature of the mash to 168 F and holding it there for several minutes. This ensures the deactivation of the amylase enzymes, halting the conversion of dextrins to fermentable sugars. It also reduces the viscosity of the wort, helping to make the lautering easier and more efficient. There is some controversy whether this step is necessary depending on the final mash temperature. However it is generally agreed that the best extraction rates are achieved when the mash is heated to this range.
The mashing process begins by doughing-in the crushed grains with approximately 1-2 liters of water per pound of grain. The starch granules take up water with the aid of liquefaction enzymes, and the rests described above are carried out according to the degree of modification of the malt. The simplest mashing method is the single-step infusion, where the malt is combined with hot water to reach a temperature appropriate for starch conversion. This is the method of choice for fully-modified malts such as those used to brew British ales. It has the advantage of requiring a minimum of labor, equipment, energy and time, but prohibits the use of undermodified malt or adjuncts. A step-infusion mash allows a little more flexibility by moving the mash through a series of temperature rests. The temperature is increased by external heat or the addition of boiling water. This requires more resources than a simple infusion mash, but undermodified malts may be used.
Decoction mashing involves the removal of a thick fraction of the mash (usually one-third) and running it through a brief saccharification rest at a relatively high temperature. It is then boiled it for 15-30 minutes before mixing it back into the main mash. This is repeated as many as three times, depending on the modification of the malt and the beer style. The decoction helps explode starch granules and break down the protein matrix in undermodified malt, improving the extraction efficiency, and also promotes the formation of melanoidins. These compounds are formed from amino acids and reducing sugars in the presence of heat and are responsible for the rich flavors in malty lagers. This mashing method is the most resource intensive, but is the traditional method for many lagers. A possible side-effect of the extended mash schedule is the extraction of higher levels of tannins and DMS precursors from the grain husks, though this is not significant at typical mash pH levels.
A fourth mashing method is the double mash, which can be viewed as a combination of infusion and decoction. As the name implies, it involves two separate mashes: a main mash consisting of crushed malt, and a cereal mash consisting of raw adjuncts and a small charge of crushed malt. The latter is boiled for at least an hour to gelatinize the starches and is then added to the main mash, which has undergone an acid rest. The mixture is then cycled through protein and saccharification rests using the step-infusion method. The double mash is the most common way of producing beer styles such as American light lagers that contain a high proportion of corn grits or rice.
Lautering is the process of separating the sweet wort from the grain fractions of the mash. It is usually done in a vessel, appropriately called a lauter tun, that holds the grain and wort with some form of strainer in the bottom to separate the liquid wort from the grain. In most homebrewing setups, the mash tun, where the mash process occurs, and the lauter tun are the same unit. Where the brewer chooses to utilize two vessels and convey the mash contents from the mash tun to a special purpose lauter tun care must be taken to not introduce oxygen into the hot wort. This hot side aeration can introduce oxidative off flavors the finished beer that are often perceived as sherry-like, wet paper or cardboard-like.
Lautering consists of draining the wort off the grain and sparging, or the addition of hot liquor (treated brewing water) to the top of the grain bed to rinse the sugars from the grain. This procedure should be done slowly, with the wort returned to the tun until the run-off is clear. This initial runoff and return of wort to the lauter tun is called a vorlauf and is critical to preventing astringency and haze in the finished beer. Lautering too fast will give poor yield, poor extraction rates, and possibly flush starch and protein fractions into the wort. Failing to re-circulate the initial runoff through the lauter tun until it is reasonably clear will have a similar effect.
A temperature range of 160-170 F should be maintained throughout the entire process; this ensures that the greatest extraction of sugars from the grain without excess tannin extraction from the husks. Temperatures above 170 F will leach tannins and permit undissolved starch balls to explode and get past the filterbed, and gums and proteins may also be released into the wort. This starch will pass on to the finished beer without being fermented until broken down over a period of time by wild yeast or bacteria present.
Another potential problem is a stuck sparge, which may be caused by an inadequate amount of filtering material in the grain bed, usually barley husks, that allow wort to pass freely while holding back the bits of material to be filtered. When mashing with high quantities of wheat or rye malt that will not have their own husks to aid as a filter, it's usually necessary to add additional filter material such as rice hulls, which themselves are neutral to the flavor or gravity of the resulting beer. Wheat, rye, oats and some other cereal grains also contribute a much higher proportion of gums that can help cause the stuck mash. These often require a beta-glucanase rest in order to break down these gums and aid the resulting sparge.
Sparging is the addition of rinse water, or hot liquor, to the lauter tun. In general the water chemistry of the sparge water should match that used in mashing. The pH should be approximately 5.7 in order to prevent the mash pH from exceeding 6.0, which promotes the extraction of excess tannins.
The sparge rate should be slow, with the water (at 170 F) added gently so that the filter bed is not disturbed. A hydrometer reading of the first runs from the tun should be about twice the value desired in the finished beer. If not, it should be returned to the tun. Sparging should cease when the gravity drops to below about 1.010 or the pH of the runoff increases above 6.0. Monitoring of the runoff is essential in order to stop the collection of wort before excess tannins are extracted. Learning to taste the sweet wort to recognize when to stop the collection will provide the brewer with an intimacy of the process that doesn't require the use of the hydrometer or pH meters and papers.
Boiling wort is normally required for the following reasons:
A minimum of a one hour boil is usually recommended for making quality beer. When making all grain beer, a boil of 90 minutes is normal, with the bittering hops added for the last hour. One exception to boiling was historically used to brew the Berliner Weisse style. Here, the hops were added to the mash tun, and the wort is cooled after sparging and then fermented with a combination of lactobacillus from the malt and an ale yeast.
Boiling for less than one hour risks under-utilization of hop acids, so the bitterness level may be lower than expected. In addition, the head may not be as well formed due to improper extraction of isohumulones from the hops. A good rolling boil for one hour is necessary to bind hop compounds to polypeptides, forming colloids that remain in the beer and help form a good stable head. An open, rolling boil aids in the removal of undesired volatile compounds, such as some harsh hop compounds, esters, and sulfur compounds. It is important to boil wort uncovered so that these substances do not condense back into the wort.
Clarity will be also be affected by not using at least a full hour rolling boil, as there will not be a adequate hot break to remove the undesired proteins. This will also affect shelf life of the bottled beer, since the proteins will over time promote bacterial growth even in properly sanitized beer bottles. The preservative qualities of hops will also suffer greatly if the wort is not boiled for one hour, as the extraction of the needed compounds will be impaired.
Boiling wort will also lower the pH of the wort slightly. Having the proper pH to begin the boil is not normally a problem, but if it is below 5.2, protein precipitation will be retarded and carbonate salt should be used to increase the alkalinity. The pH will drop during the boil and at the conclusion should be 5.2-5.5 in order for proper cold break to form and fermentation to proceed normally. Incorrect wort pH during the boil may result in clarity or fermentation problems.
The effects of boiling on the wort should match the intended style. It is often desirable to form melanoidins which are compounds produced by heat acting on amino acids and sugars. These add a darker color and a maltier flavor to beer. When desired, an insufficient boil will not form enough melanoidins for the style. Boiling the initial runnings of high gravity wort will quickly caramelize the sugars in the wort. This is desired in Scottish ales, but would be inappropriate in light lagers.
Vigorously boiling wort uncovered will evaporate water from the wort at a rate of about one gallon per hour, depending the brewing setup. In order to create a beer with the appropriate target original gravity, changes in the wort volume must be taken into account. Longer boil times or additions of sterilized water may be required to hit the target gravity.
After boiling for a sufficient amount of time, the wort should be chilled at rapidly as possible, using either an immersion or counter-flow system. This minimizes the risk of contamination by Lactobacillus or wort-spoilage bacteria and produces an adequate cold break. This cold break consists of protein-protein and protein-polyphenol complexes and is often promoted by the addition of Irish moss to the kettle near the end of the boil. There is some debate on whether the cold break should be completely removed. On one hand, it can provide carbon skeletons that can be used by the yeast for sterol synthesis, but on the other, excessive levels may lead to elevated levels of esters and fusel alcohols and promote the formation of chill or permanent haze in the finished beer.
Hops are the spicy and bitter counterpart to the malt backbone of beer; they are essential to beer as we know it. Prior to the widespread acceptance of hops, various bitter herbs, seasonings, and spices were used to balance the malt sweetness. Hops also contribute many secondary attributes to beer: they provide a measure of bacteriological stability, aid in kettle coagulation, and contribute to a stable head.
Brewers' hops are the cone-like flower of the Humulus lupulus vine, a relative to the cannabis plant. The essential ingredients are concentrated in the lupulin glands, located at the base of the bracteoles, or leaves of the cone. The bracteoles are attached to the central stem of the hop cone (strig). The lupulin resin contains alpha acids and essential oils that contribute the characteristic bitterness, flavor, and aroma that are associated with hops in beer. The amount of alpha acid is usually expressed as a weight percent, and is determined by extractive and chromatographic methods.
Many varieties of hops are known, though they are generally divided into two subsets: aroma and bittering hops, although some are considered to be "dual-purpose." The finest of the aroma hops are referred to as "noble," due to their prized aromatic and subtle bittering properties; the noble varieties include Saaz, Spalt, Tettnanger, and Hallertauer Mittelfrueh, although some sources list other varieties. Aroma hops are generally lower in alpha acid content, but contribute desirable flavor and aroma characteristics. Bittering varieties are higher in alpha acid content, but their flavor and aroma characteristics are generally considered to be less refined. There are no hard and fast rules about aroma, bittering, and dual-purpose hops; the categorization is subjective. Generally, aroma hops consist of such varieties as Saaz, Tettnanger, Hallertauer, Spalt, East Kent and Styrian Goldings, Fuggles, Cascade, Willamette, Liberty, Crystal, Ultra, and Mount Hood. Bittering varieties include Brewer's Gold, Nugget, Chinook, Eroica, Galena, and Bullion. Dual-purpose varieties include Northern Brewer, Columbus, Cluster, Perle, and Centennial, among others.
Hops were introduced in beer making prior to 1000 A.D., and came into widespread use in the 16th century when they were legislated as a required ingredient in the famous Reinheitsgebot, or German Beer Purity Law of 1516. Hops are still grown in many of the traditional regions, such as the Zatec region of the Czech republic, home of Zatec Red, or Saaz variety. Hop varieties have been enriched through intensive cross-breeding, which has given us many of the newer, disease-resistant varieties.
Bitterness arises from the alpha acids, which consist of humulone, cohumulone, and adhumulone; the proportions of each will vary according to hop variety. They are isomerized into iso-alpha acids in a vigorous boil, rendering them much more soluble in the wort, in addition to increasing their bitterness. The essential oils, which contribute to flavor and aroma of the finished beer, consist of dozens of compounds. Many of these are volatile, and hence do not survive extended boil times. For this reason, flavor and aroma hops are generally added during the last 30 minutes of the boil.
Brewing hops are available in many forms: whole hops, plugs, pellets, and extracts. Whole hops are simply dried hop cones, and are the most traditional form of hops. Plugs (also known as type-100 pellets), are whole hops compressed into 1/2-ounce disks. Pellets are ground into powder, then compressed into 1/2-ounce disks. Pellets are ground into powder, then extruded through a die. Hop extracts include isomerized extracts, which may be used to add bitterness; hop aroma essences are also available.
The bitterness imparted by hops is quantified in various ways, with varying degrees of precision. The simplest method is the Alpha Acid Unit (AAU), also known as the Homebrew Bittering Unit (HBU). This basic measure is simply the weight of hops in ounces times the alpha-acid content, expressed as a percent. In order to be meaningful, the brew length must be specified when using AAUs or HBUs. The main downfall of the AAU/HBU quantification method is that it describes the potential bitterness without accounting for many critical factors which determine the actual bitterness.
The more precise method of quantifying hop bitterness is the International Bittering Unit, or IBU. The IBU is a measure of the concentration of isomerized alpha acids present in the finished beer, and is expressed in milligrams per liter, or parts per million (ppm). The relationship between the quantity of hops used and the IBU level depends on many factors: length of the boil, wort gravity, vigor of the boil, wort pH, age/condition of hops, hop form (whole, plugs, or pellets), hopping rate, plus several other less important elements. The relative IBU level does not always translate directly to the perceived bitterness of the finished beer. The ionic makeup of the brewing water, particularly carbonate and sulfate levels, directly affect the perception of bitterness. The degree of attenuation also plays a role in the amount of bitterness that is needed to reach a balance for a given style.
The IBU content of a beer may be expressed as: IBU = 7489 x (W x A x U)/V, where 7489 is a conversion from milligrams/liter to ounces/gallon, W is the weight of hops in ounces, A is the alpha acid content as a decimal, U is a percent utilization factor, and V is the final volume of beer, in gallons. The most important variable in the equation is the utilization factor, which depends on the aforementioned parameters. Utilization normally tops out at about 30 % in the home brewery; often, it is significantly lower. Some additional factors which affect the value of U are boiling temperature, whether or not hop bags are used, and filtration losses. U is the product of all correction factors and may be estimated by any of several methods for each set of conditions. In any case, a different utilization is typically assumed for each hop addition (when multiple additions are used); in this manner, the IBU contribution for each hop addition may be estimated, then totaled. It should be noted that the only way to determine the IBU level in the finished beer is through a direct measurement in the laboratory.
The relationship between the various correction factors and hop utilization is often not simple, but certain tendencies are well known. Utilization is reduced by: reducing the contact time of hops with boiling wort; reducing the boiling temperature of the wort; increasing the wort gravity; using whole hops instead of pellets; increasing the hopping rate; using hop bags to contain the hops during the boil; using older hops; decreasing wort pH; using more flocculant yeast; and filtering the beer. Some bitterness is also lost to oxidation or staling of the finished beer.
The desired level of bitterness, as measured by IBUs, varies widely for different styles. For example, an Oktoberfest would be expected to have about 20 to 30 IBU, while a Bohemian Pilsener might have 30 to 40 IBU. Each style has different bitterness, flavor, and aroma expectations; only the alpha-acid level may be accurately quantified. Another way to characterize the bitterness of a given style is the BU/GU ratio introduced by Ray Daniels. This is simply the IBU content divided by the last two digits of the original specific gravity.
Hops are often added at different points in the brewing process, with the goal of contributing bitterness, flavor, or aroma to the finished beer. Bittering hops are usually most efficient at yielding their iso-alpha acids with 60 to 90 minutes of vigorous wort boiling. Hops boiled for 10 to 40 minutes are often referred to as "flavor hops," since they contribute less bitterness, but retain some essential oils which contribute characteristic flavors. Hops added at or near the end of the boil contribute little or no bitterness, some flavor, and aromatic quality to the finished beer. Hops added during or after fermentation ("dry" hops) contribute a fresh hop aroma.
Hop-derived compounds can also be altered in the finished beer. Oxidation (staling) reduces bitterness, and may also add a harsh edge to flavor, as well as diminishing aroma. One of the most well known hop-derived off flavors is that of skunkiness. This phenomenon is usually ascribed to light exposure, and is often described as "lightstruck;" however, it has been demonstrated that the free-radical reaction may be initiated by heating/ cooling cycles, as well. The offending compound, prenyl mercaptan, results from the combination of a 3-methyl-2-butene radical (derived from an iso-alpha-acid) with a thiol radical (present in malt constituents).
The newly re-discovered technique of first wort hopping is also gaining favor among homebrewers. It essentially consists of adding a portion of the hop charge (some insist that most or even all of the hops should be added at this point) to the first sweet wort runnings from lautering, during which time the higher pH is thought to extract some of the finer qualities of the hop flavor. The hops are kept with the wort throughout the boil, and contribute a more refined bitterness, though the exact amount is a matter of debate. What is beyond debate is the fresh hop flavor imparted by first wort hopping; some have speculated on possible formation of stable complexes, or perhaps esters, at the temperature range encountered in the mash runoff. Another possibility is the removal of undesirable, somewhat volatile constituents during the extended heating and boiling time; this coincides with the observation that even with increased IBU levels provided by first wort hopping, the resulting bitterness is usually described as smoother and more pleasant. Surprisingly, the technique also contributes aroma; in fact, first wort hopping has been suggested as a replacement for late hop additions. Less clear is how the aroma boost compares to dry-hopped aroma. The technique is an old German method that was originally used for hop-centered styles, such as Pilsener; recently, it has gained favor for a wide range of homebrewed styles. It was originally intended as a means for extracting more bitterness, and it has been found (analytically) to provide a favorable bittering and flavor compound profile.
Hop varieties are often associated with particular beer styles; in fact, some styles are virtually defined by their hop character. British ales are normally associated with native hop varieties (East Kent Goldings, Northern Brewer, and Fuggles, for example), and most are expected to embody the characteristic flavor and aroma attributes associated with these hop varieties.
Continental styles, particularly the more hop-oriented ones, are also often associated with more local Continental hop varieties. Bohemian Pilseners, for example, are partially defined by the characteristic spicy Saaz aroma and flavor. On the other hand, German Pilseners are more usually associated with German hop varieties, such as Tettnanger, Hallertauer Mittelfruh, and Spalt. Altbiers, although often subdued in hop aroma and flavor, are also normally associated with the bitterness attributes that arise from the use of low-alpha ("aroma") hops. Even the less hop-accented styles, such as bock or Oktoberfest, benefit from the additional flavor complexity that the judicious use of Continental low-alpha hop varieties provides.
American styles, especially such hoppy examples as American pale ale and American brown ale, benefit greatly from the floral, citrusy character of the dominant American varieties such as Cascades, Centennial, Columbus or Chinook. In fact, it is often the hop character that sets these styles apart from their European prototypes.
It is important to note that the region of cultivation is as important as the hop variety in determining the character of the crop. Classic European hop varieties grown under a different climate in the United States exhibit different characteristics than the same varieties grown on European soil. Therefore, the place of origin is every bit as important as the genealogy when selecting the appropriate hop variety for a particular application.
Most beer styles are made using one of two unicellular species of microorganisms of the Saccharomyces genus, more commonly called yeast. Generally, either an ale yeast (known as S. cerevisiae) or a lager yeast (known as S. carlsbergensis or by older terminology S. uvarum) is used for the appropriate style. Functionally these yeasts differ in their optimum fermentation temperatures, ability to ferment different sugars, environmental conditions, and ability to settle out upon completion of fermentation, and production and/or metabolism of fermentation by-products. The choice of the strain of ale or lager yeast and how these factors are controlled during the various stages of fermentation will determine how well a beer is made to style. While a list of all the possible strains is beyond the scope of this guide, readers are encouraged to review reference (1) for a more thorough review.
One of the common terms used to describe yeast is apparent attenuation. The attenuation of a particular yeast describes its ability to decrease the original gravity of wort upon fermentation. It is commonly listed as a percent, in which the numerator is the difference between final and original gravity and denominator is the original gravity. Because the density of ethanol is less than water, when a hydrometer is used to measure this attenuation, it will be measuring the apparent attenuation not the real attenuation (if the alcohol was replaced by water). Another common term used to describe different yeasts is flocculation, which is the ability of the yeast to settle out of the beer upon completion of fermentation; it can vary significantly with strain.
The environmental conditions that differ with each yeast type and strain are alcohol tolerance, oxygen requirements, and sensitivity to wort composition. Alcohol tolerance describes how well a yeast will continue to ferment as the alcohol concentration increases during fermentation. Most lager yeasts can ferment up to about 8% alcohol by volume, and some ale strains can ferment up to 12% (2,3). Oxygen requirements can differ with each strain as well; some need much more oxygen to be able to ferment without problems. Lastly, different worts will have different relative amounts of sugars present. The various strains can respond differently to the same wort upon fermentation.
The by-products that are produced (and also be metabolized) by the yeast are esters, fusel alcohols, diacetyl, and sulfur compounds. Esters are produced by yeast combining an organic alcohol and acid. While approximately 90 different esters have been identified in beer, ethyl-acetate, isoamyl-acetate and ethylhexanoate are most commonly above their flavor thresholds. These impart a fruity, sweet aroma to the beer. Another by-product of fermentation is fusel alcohols, which contain more carbon atoms than the most common alcohol, ethanol. These are produced by the metabolism of amino acids (4), and tend to add harsher, more solvent-like tones the beer. Yet another by- product is diacetyl, which is generally reduced to more benign compounds during the secondary fermentation, but premature removal of the yeast can lead to elevated levels. Its presence imparts a buttery note to the beer. It is produced by an oxidation reaction which can be repressed by the production of the amino acid valine (5). Lastly, there are several sulfur compounds that can be produced by the yeast. One of these is hydrogen sulfide, which smells like rotten eggs. Other sulfur compounds exist, but their production is not yet completely understood (1).
Ale Yeast, for the purposes of beer fermentation, tend to work best in the 55-75 F temperature range. Apparent attenuation can range from 69 to 80%. These yeasts can fully ferment the common sugars glucose, fructose, maltose, sucrose, maltotriose and the trace sugars xylulose, mannose, and galactose. They can partially ferment raffinose. These yeasts have traditionally been called top fermenting because they form colonies (groups of yeast that cling together) that are supported by the surface tension of the beer. Ale yeasts produce esters since they require higher temperatures to remain active. Styles that use these yeasts have varying degrees of fruity and sweet smelling aromas. It should be noted that the yeast used to produce the German weizen style are special strains that generate high concentrations of the clove-like phenols and "bubblegum" and "banana" esters, which are the signature of this style.
Lager Yeast generally tend to work best between 46-56 F, but California Common Lager yeast is an exception having a range of 58-68 F. Apparent attenuation usually ranges from 67-77%. Lager yeasts can ferment raffinose in addition to the sugars that are fermentable by ale yeasts. These yeasts have traditionally been called bottom fermenters, since they do not cling together to form colonies on the surface, but instead fall to the bottom of the fermenter. Lager yeasts can be further subdivided into the Frohberg type (also called dusty or "powdery") which ferment quickly, and do not flocculate as well. Due to the longer time it remains suspended in the wort, this subtype will have a greater attenuation. The other subtype of lager yeast is the Saaz type (also called the S.U. or "break"). These strains tend to flocculate more readily, and hence tend to have a lower attenuation (6). Lager yeasts, in comparison to ale yeasts, produce beers that lack the esters and fusel alcohols, since they are active at cooler temperatures. Lager beer styles should have a cleaner aroma to them, reflecting only the malt and/or hop aromas used to make the wort.
Bacteria, specifically Lactobacillus delbrueckii, is used in the production of the Berliner Weiss style of wheat beer with an intense lactic sourness. Other microorganisms are also used in the production of some Belgian ales, specifically lambics. Lambics have varying degrees of sourness which is appropriate for their style. Yeasts of the Brettanomyces genus, and various bacteria generate these flavors. Bacteria are commonly divided into two broad classes based on a laboratory Gram stain. The Gram-negative bacteria involved in lambic production are Escherichia coli and also various species of Citrobacter and Enterobacter, but fortunately they cannot tolerate even moderate alcohol levels and do not survive in the finished beer. The Gram- positive bacteria involved are from genus Pediococcus and Lactobacillus. These microorganisms use a different pathway than that of Saccharomyces yeast known as a mixed acid fermentation pathway. It involves the esterification of the various alcohols to the corresponding carboxylic acids, thus generating the sourness (7).
When yeast are pitched into fresh wort, the overall process of fermentation can be divided into several stages, all of which are part of the life cycle. While these stages can each be described separately, the transitions between each are continuous and should not be thought of as distinct phases. Also the relative time spent in each phase depends on several factors including the composition of the wort, the environment and the amount of yeast pitched.
The first phase of the cycle is called the lag phase. During this time the yeast will adapt to the new environment they are now in and begin to make enzymes they will need to grow and ferment the wort. The yeast will be utilizing their internal reserves of energy for this purpose, which is the carbohydrate glycogen. The yeast will acclimatize itself and assess the dissolved oxygen level, the overall and relative amounts of the amino acids and the overall and relative amounts of sugars present. Some of these amino acids, small groups of amino acids called peptides, and sugars will be imported into the cell for cell division. Normally this period is very brief, but if the yeast is not healthy, this period can be very protracted, and ultimately lead to problematic fermentation (8,1).
Based on these factors, the yeast will then move into the next phase of the life cycle, the growth phase. During this time the yeast will start to divide by budding to reach the optimal density necessary for the true fermentation. If an adequate amount of healthy yeast has been pitched and the proper nutrients are present, there should only be one to three doublings of the initial innoculum. The oxygen that was used to aerate the wort is absorbed during this time to allow the yeast to generate sterols, which are key components of the cell wall (9). It has also been proposed that cold trub can provide the unsaturated fatty acids needed for sterol synthesis (10, 11). Furthermore, it has been proposed that if an adequate amount of yeast has been pitched, such that cell growth is not necessary, then the oxygenation is not necessary (9, 12). While this theory has not been completely accepted (13, 14), perhaps further research will elucidate other variables which may be involved in this phenomenon. This sterol synthesis is the default pathway used in an all malt wort; however if the wort contains greater than 0.4% glucose then this pathway will not be used and the yeast will instead ferment the glucose, even in the presence of oxygen. This effect is called glucose repression, or the Crabtree effect.
Following the growth phase, the low kraeusen phase of primary fermentation begins. During this time the yeast begins anaerobic metabolism, since all of the oxygen has now been depleted. This is characterized by a foam wreath, which has previously existed on the sides, now migrating to the center of the surface. The yeast have now completely adapted to the condition of the wort and transport of both amino acids and sugars into the cells for metabolism will be very active. During this period fusel alcohols and diacetyl can be produced. To minimize the formation of fusel alcohols, one should try to keep the temperature down, make sure that adequate dextrinous sugars are available, and minimize the amount of hot trub present in the yeast cake. To minimize the diacetyl in the finished beer, one should try to avoid the reintroduction of oxygen, excessive cooling of the fermentation in later stages and premature removal of the yeast.
At the high kraeusen stage following this, an ale yeast will have metabolized most of the sugars present in the wort. A lager yeast, on the other hand, may still be in the growth phase while also reducing the extract by four gravity points/day. Lager yeast will be metabolizing most of the sugars during the high kraeusen phase. Following this phase is the late kraeusen phase. In lager yeasts this can be very important, since it is during this time that the yeast begin to metabolize some of the fermentation by-products they had previously excreted during the low kraeusen phase. Specifically, a diacetyl rest may be performed to help with the re-absorption and subsequent reduction of the diacetyl and the related 2,3 pentanedione during this time. The temperature of the beer may be allowed to rise up to 68 F. Generally as the extract reaches its terminal point the yeast will begin to flocculate out. It is important not to chill the beer too quickly, which might cause premature flocculation before the fermentation has been completed and all the by-products have been reabsorbed. The general rule of thumb is no more than 5 F/ day, otherwise it is possible to cold shock the yeast.
When the yeast begins to flocculate, the beer is generally racked into a secondary fermenter, which allows for the attenuation of the last remaining extract, usually consisting of the trace sugars. Also removal of the excess yeast and trub will prevent formation of off flavors due to autolysis and/or reactions with trub substrates. For ale styles this period may be very brief, while lager styles may be four to six weeks, or even as long as six months in the case of strong lager styles. It is important during this time to prevent reintroduction of air, since this can lead to oxidation flavors and may introduce contaminants that can infect the beer.
During packaging of the beer, fresh yeast may often be reintroduced, particularly if it has been lagered for an extended period of time and/or the remaining yeast are not that viable. Two common methods are 1) bottle conditioning, or the addition of a fresh yeast starter and corn sugar (glucose), as is commonly done for Trappist-style Belgian ales, and 2) kraeusening, or the addition of freshly fermenting beer as is often practiced with German lagers. For bottle conditioned beers, a 250 ml starter is usually added for a 5 gallon batch along with the sugar; which provides fresh yeast to metabolize the added sugar. In the case of kraeusening, an actively fermenting batch at high kraeusen stage is added to the beer being primed. The volume of kraeusen added is 20% by volume of the beer being primed. Adding this actively-fermenting beer serves two purposes; it carbonat