Knowledge Assessment Flashcards
(17 cards)
Knows the multiple roles of yeast in brewing.
Fermentation, alcohol production, flavor and aroma, carbonation and foam stability, mouthfeel and acidity, flocculation and clarification
Can delineate differences in process and product in production of ales vs lager.
Ale: top-fermenting yeast, warmer temperatures (18-21C), faster fermentation (few weeks), fruitier and spicier with more complex flavor profile, wide range of flavor profiles (hoppy IPA to malty stouts)
Lager: bottom-fermenting yeast, cooler temperatures (10-13C), slower fermentation (weeks or months), cleaner and crisper and more balanced flavor profile with subtle flavors of hops and malts, focus on clean and refreshing taste (crisp pilsners to malty bocks)
Knowledge of kinds of fermentable sugars and various products of fermentation.
Fermentable sugars: glucose, fructose, sucrose, maltose, maltotriose
Products: ethanol, lactic acid, carbon dioxide, fusel oils, esters, phenolics
Knows the various phases during the fermentation process.
Lag phase: yeast acclimate to new environment and shift from dormancy to aerobic respiration
Growth phase: exponential growth in number of cells and consumption of sugars under anaerobic fermentation
Stationary phase: growth rate of cells equals their death rate
Dormancy/death phase: consumption of fermentable sugars, cell growth, and cell flocculation are all complete
Can name the various kinds of yeast and bacteria used in brewing and their unique behaviors.
Ale yeast (saccharomyces cerevisiae): top-fermenting, warmer temperatures, fruity and spicy (sometimes floral)
Lager yeast (saccharomyces pastorianus): bottom-fermenting, cooler temperatures, cleaner and crisper
Lactobacillus: sour/tart flavor
Pediococcus: cleaner, milder sourness
Brettanomyces: barnyard-like flavor, “funky” aromas and flavors (woody, earthy, putrid, animal, savory, veggie, fruity, dairy, floral, chemical/solvent)
Know how far back and where brewing started.
5000 BC, Ancient Sumeria (modern Iraq, Iran)
Recognize the limitations of brewing in its earliest history.
Basic equipment, no understanding of yeast (relied on natural fermentation = inconsistent and undesirable results), limited ingredient variety and quality (no hops, grut = mixture of herbs and spices), limited shelf life (lack of standardization and quality control, no refrigeration or pasteurization)
Brewing was a female activity, lower alcohol content, used as safe and nutritious beverage
Discuss the “Ale Renaissance” (500 - 1066 AD) and “Beer Reformation” (1000 - 1500 AD).
Ale Renaissance: early medieval Europe (Anglo-Saxon England), made ale without hops, brewed mostly by women in households or small communities, used gruit instead of hops, ale was a staple food source that was consumed daily by all ages, passed down orally and varied widely by region, ale was essential for nutrition and hydration, brewing was a key domestic skill, some ale production became semi commercial due to growing demand
Beer Reformation: Middle Ages in Europe, introduction and widespread use of hops in brewing, clear distinction between ale (unhopped) and beer (hopped), gave beer longer shelf life and better microbial stability, brewing shifted to monasteries and towns/guilds, brewing practices became more regulated and consistent, hopped beer enabled long-distance transport and trade, laid the groundwork for modern brewing industry
Discuss innovations in brewing during the industrial revolution.
Steam engine: provided reliable and powerful source of energy for large-scale production
Thermometer and hydrometer: monitor and control temperature and sugar content, leading to more consistent and predictable results
Drum roaster: creation of darker, roasted malts
Pasteurization: extended shelf life of beer and ensured its safety during distribution
Bottling and mass production: more widely available and affordable for consumers
Discuss the ups and downs in the brewing industry over the twentieth century.
Ups: repeal of Prohibition led to surge in brewery operations and beer consumption, rise of national brands (popularizing mass-marketed beers), introduction of canned beer (more readily available and affordable), legalization of brewpubs, craft beer revival (breweries experimenting with new flavors and brewing techniques)
Downs: Prohibition forced breweries to close or diversify into other products, rise of large national breweries led to decline and closure of smaller and local breweries, dominance of national brands resulted in homogenization of beer styles (local and regional specialties disappearing), challenging for small breweries due to large scale production and marketing costs of national brands
Can identify minerals important in beer brewing.
Calcium
Magnesium
Sodium
Hydrogen
Bicarbonate
Carbonate
Chloride
Sulfate
Can explain the difference between hardness and alkalinity.
Hardness: amount of dissolved calcium and magnesium in water
Alkalinity: water’s ability to resist changes in pH (buffering capacity); sum of concentrations of bicarbonate, carbonate, and hydroxyl anions in water
Knows the functions of various minerals in beer brewing.
Calcium: acidifies the mash and reduces mash pH
Bicarbonate: increase mash pH; too high and it can impede the cold break and emphasize bitterness in a harsh way
Sulfate: enhances bitterness in beer and slightly lightens color
Chloride: lowers the bitterness perception and enhances maltiness of beer
Sodium: enhances sweetness and body in certain dark beers
Magnesium: enhances yeast health
Understands how certain cations adjust mash pH.
Reacts with alkaline buffers (carbonate and bicarbonate) in the water, effectively neutralizing them and lowering the overall pH
High concentration of alkaline buffers can counteract the effects of calcium and magnesium, making it difficult to achieve desired pH range
Can calculate the amount of mineral required to produce a targeted ppm of an anion or cation.
Contribution is based on relative weight of ion to total weight of compound added to water
(weight x ion contribution)/volume = final concentration
Can explain what is meant by “faults in beers.”
Flavor deterioration caused by chemical changes of organic compounds in beer
Can provide examples of three faults in beers; name the chemical responsible; and explain the origin.
Green apple
Acetaldehyde: oxidation of ethanol in presence of excess oxygen, precursor to ethanol during yeast fermentation
Sour
Lactic acid: low mash temp, airborne infection, unsanitized equipment post boil
Acetic acid: airborne infection during fermentation, produced by commercial yeast strains
Nuttiness
Benzaldehyde: oxidation, higher gravity beers, prolonged heat post fermentation, byproduct of yeast strains, oxidized melanoidins
Papery
Trans-2-nonenal: oxidation of unsaturated fatty acids released from malts during mashing (hot side aeration, post fermentation aeration, long beer storage times, exposure to high temperatures during storage)
Skunky
3-methylbut-2-ene-1-thiol: beer exposed to direct sunlight or UV light
Phenolic
4-vinyl guaiacol: phenolic off-flavor positive yeast
Barnyard
4-vinyl phenol: bio-transformation of ferulic acid into 4-vinyl phenol by Brettanomyces yeast
Medicinal
Chlorophenols: chlorine sanitizers, over sparging, infection, chlorophenols in water
Fruity/solvent
Ethyl acetate (fruity at low, solventy at high)
Ethyl hexanoate (apple)
Isoamyl acetate (banana/pear)
Phenylethyl acetate (flowery, honey, sweet)
Yeast strains/stress, higher fermentation temperatures, wild yeast, non-food grade plastic, higher wort gravity
Canned corn
Dimethyl sulfide: bacterial contamination, precursors to DMS naturally present in malted grains
Butterscotch
Diacetyl: natural fermentation product from converted sugars during early stages of fermentation, lower fermentation temperatures, mutated yeast strain, premature racking/fining/lagering
Grainy/husky
Isobutylaldehyde: excessive grain crush, high corn/adjuncts, boiling grains/improper decoction procedures
Astringent
Polyphenols: excess tannin extraction, high sparge temperatures/excessive sparging, mash pH exceeds 6.0/alkaline water
Metallic
Ferrous sulphate: unprotected metals dissolved in wort, contact with iron, lipids from malt or adjuncts
Rancid
Butanoic and hexanoic acid, octanoic and decanoic acids, geosmin: bacterial infection/yeast autolysis
Fecal
Indole: bacterial infection in water, equipment, and yeast
Cheesy
Isovaleric acid: organic acids formed during improper hop storage or bacterial infection
Alcoholic
Fusel oils produced during fermentation: high fermentation temperature, low mash temperature, yeast strain, insufficient oxygen levels during yeast adaptation
Rotten eggs
Ethanethiol, mercaptans, hydrogen sulfide: yeast strain, yeast autolysis, infection by anaerobic bacteria
Sweet
Low attenuation/cold crashing, presence of maltose and maltotriose
