α-acids, in hops resins, 54–55
α-amylase
action in mashing, 40–41
as liquefaction enzyme, 46
α/β ratios in hops, 56–57
Abuse in trade, 142
Acetic acid bacteria, 122–123
Acid-forming enzymes in malting and mashing, 38
Acidification
by direct mash versus salt additions, 13
Acid rest, 46
Additives covering staling effects, 127
Africa, use of malted sorghum, 45
α-glucans (amylopectins), 18–20, 40–41
Aldehydes, staling of, 135
Ales, dimethyl sulfide levels of, 33
Alkaline water
boiling of, 10–11
treatment residual, 12
treatment with lime, 10–11, 11
Amadori rearrangement, during kilning, 43–44
American Society of Brewing Chemists (ASBC)
°ASBC malt color units, 41–42, 42
measurement method of beer stability, 143, 143, 144
study of extract and ethanol levels, 93
Amines, effects on beer flavor, 36
Amino acids
assimilation rate in fermentation, 24, 25, 25
free amino nitrogen (FAN) content in wort, 26
percentage absorbed by yeast in fermentation, 100–101
as proteins building blocks, 23–29
as source of nitrogen in brewing, 23–29
Amylopectins. See α-glucans
Amylose sugars, 17–18
Anabolic reactions, definition of, 94
Anti-fungal spraying source of sulfury flavors, 64–65
Antioxidants, natural source in iso-α-acids, 136–137
Arabinose, 21
Aromatic rings, role in brewing, 30–32
Astringent compounds
extraction during sparging, 51–52
materials in husks, 45–46
Attenuation
apparent/real, 48
Auto-oxidation mechanism in beer staling, 130–131
Avogadro’s number, 158
β-acids in hops, 54–57
Bacteria
in fermentation, 119–120, 120, 121, 121, 122, 122, 123, 123, 124, 124, 125, 125
heterofermentative, 121
homofermative, 122
infection as source of dimethyl sulfide, 34–35
Baeyer condensation, 136
Balling, Carl Joseph, study of extract and ethanol levels, 92
β-amylase, action during malting, 40–41
Barley
germinating, 37
moisture uptake in kernels, 1
raw, 37
B-complex vitamins, sources during fermentation, 35–36
β-D-glucose, 16
Beer
freshness and role of phenolic compounds, 31–32
phenolic compounds in oxidation, 31–32
smoothness of, 51
stability of foam, 48–49, 144, 146, 171–173
staling by lipid-active enzymes, 43
staling defects, 127–128, 128, 129–139
“white” type, 50–51
Beer, staling of. See Staling of beer
Beer haze, 31–32
chilled or temporary haze, 141
clarification of, xvii
Beer-spoiling bacteria, xiii
Belgian lambic beers, 79
Belgian “white” beers, 50–51
Berliner White Beers, 122
β-glucans
breakdown of, 46
group of carbohydrates, 20–22
Bicarbonate (HCO3-)
importance in wort production, 5
residual alkalinity (RA) equivalent amount, 12
Biological acidification, 49–50
Biological hazes in beer, 141–143, 143, 144
Biotin growth factors for yeast during fermentation, 35
Birth-scar theory of yeast multiplication, 87–89
Bitterness unit (BU), 67
“Black currant” tone in staling of beer, 128
Blanching process, 139
Bohemia, Saaz region hops, 55
Boiling of alkaline brewing water, 10–11
“Bottom cropping” of yeasts, 81
Brauwelt study, 70–71
Brettanomyces lambicus, 79
Brewing
amino acids used, 25
“nonadditive brewing,” 127
secondary effects of, xv–xvii
as series of enzyme-induced transformations, 1–2
Brewing water, 1
acidification of, 8–9, 10, 11, 11, 12
alkalinity of London and Munich waters, 13
pH value of, 9
residual alkalinity (RA), 12
treatment of alkaline water, 10–11, 11
treatment with sulfuric acid (H2SO4), 10, 11
Brewing yeasts. See Yeasts
Britain, dimethyl sulfide levels in ales, 33, 34
Browning reaction, 36
BU. See bitterness unit
Budweiser, apple-like tone, 83
By-products, as yeast signatures, 83–84
Calcium
ionic concentration of, 6
removal during water treatment, 11–12
Calcium carbonate (CaCO3), 4, 8
Calcium chloride (CaCl2), 3
Calcium ions
influence of beer fermentation, 5
inhibition of yeast growth, 36
thermal protection for mash enzymes, 5
Calcium sulfate (CaSO4), 3
Candida, impact of Crabtree effect, 94
Carbohydrates
compared with proteins, 23
defined, 15–16
modification during malting, 39, 39, 40–41
opening to enzyme activity, 47–48
reducing or nonreducing, 22
types of, 15–22
Carbonates (CO32-)
importance in wort production, 5
synergism with dark malts, 14
Carbonation of beer, 162, 162, 163–164, 165, 166
Carbonic acid and pH of wort, 6, 7
Carbon splitting in fermentation EMP pathway (glycolysis), 103
Cardboard tone and staleness in beer, 129, 136
Catabolic reactions, definition of, 94
Catty aroma in staling of beer, 128
“Cat urine” as dimethyl sulfide descriptor, 34
“Cheesy” tones, source of, 57
Chill or temporary hazes, 137, 141
Clarity of wort, 30
CO2 gas as sulfur scrubbing agent, 34, 125
Cohumulones
isomerization of, 54–55
percentage as quality indicator, 56
transformations during wort boiling, 67–69, 69, 70, 70, 71
“Cold break” in wort boiling, 78
“Cold break” in wort chilling, 29
Cold-side aeration (CSA), xiv, 129–130
Coliform bacteria source of dimethyl sulfide levels, 34–35
Color
levels/temperatures for classic malt types, 43
of malt, 41–42, 42, 43, 43, 44
Contamination of mash, 50
Coors pineapple-like tone, 83
Copper, yeast requirements for, 36
Crabtree effect of respiration inhibition in fermentation, 93–94
Cross-flow cartridge filtration, 149–150
CSA. See Cold-side aeration
Curing phase, for malt color, 42–43, 43
Currant aroma in staling of beer, 128
Cytolytic modification, measurements of, 38–39
Czech Pilseners, mineral content of, 15
Dalton’s law of partial pressures, 162
Dark beers
high sulfate levels, 14
synergism with carbonates, 14
Diacetyl production during fermentation, 113–114, 114, 115–116, 116, 117, 117, 118–119
Diastatic power (DP) of malt enzyme system, 42
Dimethyl sulfide (DMS), 32–35
in fermentation, 123, 123, 124, 124, 125, 125
formation during malting, 44–45
levels in finished beers, 33–34
precursor conversion, 45
production/reduction in wort boiling, 71–75
Dimethyl sulfoxide (DMSO)
as dimethyl sulfide precursor, 34–35
Dispensing draft beer, 169–173
Distillation in “ice beer” process, 150–151, 151
DMS. See dimethyl sulfide
DMSO. See dimethyl sulfoxide
Dortmunder Actien-Export, mineral content of, 14–15
Dortmund water treatment techniques, 14–15
Draft beer, dispensing of, 169–173
Drying phase for malt color, 42–43, 43
Ehrlich mechanism of fusel alcohol production, 107, 107
“Elegant” flavor, humulene source of, 58
Embden-Meyerhof-Parras (EMP) pathway, xii
Endosperm exposure during milling, 45–46
Entner-Doudoroff (ED) pathway in fermentation, 124, 124, 125
Enzymes
crucial to malting and mashing, 38–39
deactivation during curing, 42
role in brewing, 28–29
Essential oils in hops
components of, 57–59, 60, 61, 62, 63–65
hydrocarbon components, 57–59
Esters, flavor sources in fermentation, 111–112, 112, 113
European Brewery Convention beer-haze units (EBC), 143, 143
European Brewing Congress ⁄EBC malt color units, 41–42, 42
FAN. See free amino nitrogen (FAN)
Fatty acids
role in brewing, 29–30
role in staling of beer, 132–135
saturated types from yeast metabolism, 109, 110, 111
Fermentation
anaerobic or Pasteur effect, 93
bacterial pathogens, 119–120
acetic acid bacteria, 122–123
lactic acid group, 120, 121, 121, 122, 122
sulfur-producing bacteria, 123, 123, 124, 124, 125, 125
Crabtree effect of respiration inhibition, 93–94
EMP pathway (glycolysis)
carbon splitting, 103
formation of pyruvic acid, 91, 105
Gay-Lussac formula, 91
phosphorylation of glucose, 101–103
redox reactions of, 104
importance of, xii–xiv
initial period
acetyl coenzyme A, 91
amino acid intake by yeast cells, 99–101
formation of pyruvic acid, 91
glycogen content of pitching yeasts, 97, 98
internal energy yeast cell reserves, 97
maltose inhibition, 90
“shock excretion” of yeast cell walls, 90, 100
sterol synthesis for yeast cells, 89, 95–97, 98
Strickland reaction, 99–100
sugar intake by yeast cells, 98, 98, 99
uptake of oxygen, 95–96
wort trub stimulation of yeast metabolism, 96–97
yeast growth, 90–91
minor pathways
diacetyl production, 113–114, 114, 115–116, 116, 117, 117, 118–119
ester production, 111–112, 112, 113
fusel alcohol production, 106–107, 107, 108, 109, 110, 111
ketone production, 113, 113, 114, 118
phenol production, 107–108
removal of sulfur-containing compounds, 74, 75
stages of, 89–95
EMP pathway (glycolysis), 101–106
initial period, 95–98, 98, 99–101
true fermentation, 105–106
Filtration of beers, 153–155, 155
Fining agents, types and uses of, 144–145, 145, 146, 146, 147, 147, 148, 148, 149
First-wort-hopped beer (FWH), 68–69, 69, 70, 70, 71
Flavor
bacterial causes of, 119–120, 120, 121, 121, 122, 122, 123, 123, 124, 124, 125, 125
changes with heavy thermal loading, 76–78
disorders due to cold-side aeration, 132
effects of nucleic acids and amines, 36
ester sources during fermentation, 111–112, 112, 113
formation during kilning, 43–44
and herbstoffe, 31
nonenzymatic browning (NEB) sources, 76–78
sources of sulfury tones, 32–35, 64–65
See also Staling of beer
Flocculating behavior of yeasts, 80–81
Foam, stability of, 48–49, 144, 146, 171–173
Food-grade acids for acidification of brewing water, 10, 11
Formazin turbidity units (FTUs), 142–143, 143, 144
Free amino nitrogen (FAN)
as amino acid content of wort, 26
malt level of, 39
Freezing point of beer, 150, 150, 151, 151, 152
Friability in malt-quality index, 39
Fructose as minor wort sugar, 20
FTUs (formazin turbidity units). See formazin turbidity units (FTUs)
Furanones for wort boiling flavor source, 77–78
Furfural formation during kilning, 43–44
FWH. See First-wort-hopped beer
Gases in brewing
applications of law of partial pressures, 161–162, 162, 163–164, 165, 166
carbonation of beer, 162, 162, 163–164, 165, 166
ideal gases, 157–160, 160, 161
mole, defined, 158
Gay-Lussac’s law, 160, 160, 161
other name for EMP pathway (glycolysis), 91
Gelatinization, in mashing, 47–48
Gerianol floral aroma, 59
Germany
degrees of water hardness, 12–13
dimethyl sulfide levels in pale lagers, 34
exclusion of synthetic chemical additives, 50
mashing of diat Pils, 48
“white” beer, 50–51
Germination of kernels, 37, 37, 38
Gibberellic acid release during the malting, 38
Glucose, 16–17
Glycolysis, xii
Glycoprotein formation during mashing, 48–49
Grain
for brewing, 45
carbohydrate constituents of, 15–36
drying (kilning) of, xvi
milling of, 45–46
as protein source in brewing, 23–29
Hansensula and impact of Crabtree effect, 94
Hard resins in hops, 54
Hazes in beer, 136–137, 141–143, 143, 144
H/C ratio. See Hops, H/C ratio
Headspace for packaged beer, 166–169
Heavy thermal loading as source of off-flavors, 76–78
Henry’s law for gases in brewing, 160, 164, 165, 166–169
Herbstoffe
and beer flavor, 31
defined, xv
extraction during sparging, 51–52
Hexose compounds. See glucose
Hochkurz Maischverfahren mashing schemes, 47
Hops, xvii
α-acids in soft resins, 54–55
Amarillo floral aromas, 59
“aroma” distinction, 68
β-acids in soft resins, 56–57
“bitter” distinction, 68
bitterness source in beer, 54–55
botanical classification of, 53–54
Brewers Gold, 55
characteristics related to growth location, 55
Chinook, 56
Clusters, 55
cohumulones levels in specific types, 55
Czech types, 60
essential oils of, 57–59, 60, 61, 62, 63–69, 69, 70, 70, 71
as flavor sources, 58, 59, 63–65
fresh-leaf sources, 59, 60, 61, 62
Galena, 55
Gerianol floral aromas, 59
German types, 60
H/C ratio (humlene to caryophyllene), 58
Hersbrucker, 57
high levels and alkaline water, 14
humulone, 54–55
isomerization of hop resins, 65–67
noble flavors, 58
nonenzymatic browning (NEB), 75–78
oxidation/polymerization of resins and oils, 67–69, 69, 70, 70, 71
perception of flavor, 67
poor storage stability, 57
production/reduction of dimethyl sulfide (DMS), 71–75
pungent flavors, 58
ratio of α-acids to β-acids, 56–57
resins, 54–57
sulfury flavors, 64–65
taste comparisons, 68–69, 69, 70, 70, 71
transformations during wort boiling, 65–69, 69, 70, 70, 71
U.K. types, 61
U.S. types, 62
Hormones, release during malting, 38
“Hot break” in wort boiling, 78
Hot-side aeration (HSA), xv
in mashing and wort chilling, 129–130
HSA. See Hot-side aeration (HSA)
Humulene
to caryophyllene (H/C) ratio, 58–59, 60, 61, 62
grassy oxidation products, 64
Humulus lupulus, 53–54
Hydrocarbon components of hops essential oils, 57–59
Hydrogen sulfide (H2S)
in fermentation, 123, 123, 124, 124, 125, 125
levels and lagers, 35
Ice stabilization, 149–150, 150, 151, 151, 152
Infections, bacterial, xiii–xiv
Inositol growth factors for yeast during fermentation, 35
Iodine and color of sugar groups, 19
Irish moss fining agents, 147–148, 148
Iron, yeast requirements for, 36
Isomerization
of cohumulones, 54–55
of hop resins, 65–67
Kentucky Common Beer, 122
Kettle boil, role of amino acids, 23–24
Kettle utilization rates (KUR), 69
Kilning
forming flavor compounds, 43–44
grain drying, xvi
Kinetic molecular theory assumptions, 157–158
Kolbach index, 39
KUR. See kettle utilization rates
Labatt group industrial ice stabilization process, 150, 150, 151, 151, 152
Lactic acid (HC3H5O3)
for acidification of brewing water, 10, 11
sources of, 50
Lactobacillus amylolyticus, 50
Lactobacillus bacteria in fermentation, 121, 121, 122
Lactobacillus delbruckii, 50, 122
Lagers, 33–35
Laminaribiose, 21
Late-hopped beer, 68–69, 69, 70, 70, 71
Lautering, definition of, 45
Lauter tun, description of, 46
“Light-struck phenomenon”
source of sulfury flavors, 64
Linalool in hops basic flavors, 59
Linoleic acid, 29–30
°Linter (°L) units, 42
Lipid-active enzymes in beer staling, 43
Lipids, role in brewing, 29–30
Liquor:grist ratio, 49
London
brewing water composition, 13
dark beers, 14
°Lovibond malt color units, 42
Magnesium
role in fermentation, 5
yeast requirements for, 36
Maillard products, xvi
and dark malts, 14
formation during wort boiling, 44
formed during kilning, 43–44
roasted malt concentrations, 44
role of amino acids in malt drying/kettle boil, 23–24
in wort boiling, 75–78
Malt, xvi
for brewing, 45
carbohydrate constituents, 15–36
color of, 41–42, 42, 43, 43, 44
diastatic power (DP), 42
drying (kilning) of, xvi
Maillard products, 14
milling of, 45–46
as protein source in brewing, 23–29
pyrazines/pyrroles in dark malts, 44
storage over time, 41
temperatures for color control, 42–43, 43
Malt drying, role of amino acids, 23–24
Malting
approximate color correspondences, 42
breakdown of proteins, 28–29
carbohydrate modification of, 39, 39, 40–41
color and temperature data, 43
definition of, 36
formation of sulfur compounds, 44–45
hormone release, 38
and mashing, 45–47, 47, 48, 48, 49–50, 50, 51–52
modification of proteins and starches, 37
moisture level of, 41
starch contents of, 39
termination of process in kilning, 41
Maltose as disaccharide, 17
Maltotriose as trisaccharide, 17
Mash
acidification versus salt additions, 12–13
preparation of main mash, 50
preparation of sour mash, 50
separation from the grain, 51–52
Mash Filter 2001, 46
Mashing
key parameters for systems, 46–47, 47
lactobacilli acidification of, 122
pH establishment of, 46
process of, 45–47, 47, 48, 48, 49–50, 50, 51–52
thickness, description of, 49
Megasphaeria gram-negative bacteria in fermentation, 123–124
Melanoidin-induced oxidation in staling of beer, 134–135
Melanoidins, 36
formation during kilning, 43–44
as wort reductones, 76
Melanoids, xvi
Mercaptan sulfur compounds, 35
Metabolic pathways. See Fermentation, EMP and minor pathways
Moisture
level in malt, 41
uptake in barley kernels, 1
Molarity of gas in solution, defined, 163
Mole, definition of, 6
Monosaccharide, glucose classification, 17
Morphology of yeasts, 80
Munich
brewing water composition, 13
dark beers, 14
nonenzymatic browning of malts, 44
NEB. See Nonenzymatic browning (NEB)
Nitrogen compounds, 23–29
“Nonadditive brewing,” 127, 149–150, 150, 151, 151, 152
Noncultured yeast, xiii
Nonenzymatic browning (NEB), 43–44
in wort boiling, 75–78
Nonflocculating strain of yeast, 80–81
Nonreducing carbohydrates, 22
North America dimethyl sulfide levels in ales, 33, 34
Nucleic acids, effects on beer flavor, 36
Nutritional value of beer, 35–36
Obesumbacterium proteus bacteria in fermentation, 123, 123
Oleic acid, 29–30
O’Rourke, T.O., prediction of beer-haze stability, 144
Overdegradation of proteins, 39
Oxidation, deleterious effects of, xiv, 127–128, 128, 129–139
Oxidation hazes in beer, 136, 141, 142–143, 143, 144
Oxidation/polymerization of hop resins and oils, 67–69, 69, 70, 70, 71
Oxidation without molecular oxygen, 131
Oxygen-bearing components of hops essential oils, 59, 63–64
Oxygen for germinating kernel, 37, 38
Pale beers
alkalinity of brewing water, 9
Pale lagers, dimethyl sulfide levels and, 33–34
Pantothenate growth factor for yeast during fermentation, 35
Papery or leathery tones in staling of beer, 128
Pasteur effect, 119
Pectinatus gram-negative bacteria in fermentation, 123–124
Pediococcus bacteria in fermentation, 121, 121, 122, 122
Pentosans group of carbohydrates, 20–22
Peptides, 26–27
Permanent hazes, 141–143, 143, 144
PH
acidification of brewing water, 10, 11, 11, 12
decrease in kettle boil, 5
defined, 4
direct mash acidification versus salt additions, 12–13
of media, 7
of pale beers, 8
of wort, 51
Phenols/phenolic compounds, 1
extraction during sparging, 51–52
extraction of, 32
other sources of, 32
role in brewing, 30–32
staling of, 135–136
Phosphoric acid (H3PO4) for acidification of brewing water, 10, 11
Phosphorylation of glucose in fermentation EMP pathway (glycolysis), 101–103
Polarity, defined, 2
Polyphenols
fining agents, 144–145, 145, 146, 146
role in brewing, 31–32
Polyvinylpolypyrrolidone (PVPP) polyphenol fining agent, 145–146, 146, 147
Powdery yeast flocculation, 80–81
Protein fining agents, 146–147, 147, 148, 148
Proteins
breakdown during malting, 28–29
building blocks of, 23–29
compared with carbohydrates, 23
degradation during malting and mashing, 23–29
precipitation of, 28
ratio of soluble in total protein, 39
Proteins-degrading enzymes in malting and mashing, 38, 39
Proteolytic activity during mashing, 46–47
“Pungent” flavor, myrcene source of, 58
Pyrazines in roasted malts, 44
Pyrroles, as wort boiling flavor source, 77
Pyrroles in roasted malts, 44
Pyruvic acid formation in fermentation, 91, 105
RA. See Residual alkalinity
Real attenuation, 48
Redox reactions, definition of, 94
Reducing carbohydrates, 22
Reducing sugars, 22
Reductones, 76
Residual alkalinity (RA), 12
Resins in hops, 54–57
α-acids, 54–55
β-acids, 56–57
hard resins, 54
soft resins, 54–57
Rests temperature ranges in mashing, 46–47, 47, 48
Ribes aroma in staling of beer, 128
Rodenbach’s Grand Cru flavors in staling of beer, 128
Rotten-egg flavor in beers, 35
“Rousing” of yeasts, 81
Rye
β-glucans level, 21
for brewing, 45
Saccharomyces carlsbergenis yeasts, 79
Saccharomyces cerevisiae vars uvarum, 79
Saccharomyces cerevisiae yeasts, 79, 80, 85
Saccharomyces cervesiae vars ellipsoidens, 80
Saccharomyces diastaticus, impact of Crabtree effect, 94
Saccharomyces pastorianus, 80
Sedimenting yeast flocculation, 80–81
Shapes of yeasts, 80
Sherry-or vinegar-like tones in staling of beer, 128
Silica gel fining agents, 146–147, 147, 148, 148
Skunky characteristics of beer, 133
S-methyl methionine (SMM)
as dimethyl sulfide precursor, 33
half-life of, 73
levels in finished beers, 33
SMM. See S-methyl methionine
Smoothness of beer, 51
Sodium chloride (NaCl), in water treatment, 4
Soft resins in hops, 54–57
Sorghum for brewing, 45
Sour mash, storage of, 50
Specific gravity as carbohydrate content of wort, 26
Stability of newly bottled beer, 143–144
Staling of beer
decline in hop aroma and hop bitterness, 128, 128
and lipid-active enzymes, 43
and phenols, 135–136
stages of, 127–128, 128, 129–130
“sun struck” or “light struck” effects, 64, 133
trans-2-nonenal (T-2-N) compounds, 137–139
See also Flavor
Standard Reference Method ⁄SRM for malt color units, 41–42
Starches
conversion in the mash, 20
degrading enzymes, 38
hazes in beer, 141–142
index for degradation, 41
total extract, 41
Storage of untreated beer stressed at 37⁄C., 144–145, 145, 146, 146
S/T ratio (soluble protein to total protein), 39
Strecker degradation of Amadori complex, 43–44
Strickland reaction, the, 99–100
Sulfate levels, 14
Sulfur compounds, 1
formation during malting, 44–45
in hops essential oils, 64–65
role in brewing, 32–35
Sulfuric acid (H2SO4) treatment of brewing water, 10, 11
Sulfur-producing bacteria in fermentation, 123, 123, 124, 124, 125, 125
Sulfury flavor sources, 32–35, 64–65
“Sun-struck” effect in beer staling, 64, 133
Superattenuating yeasts, 84–85
Tank headspace, calculation of, 164, 165, 166
Tannin phenolic compounds, role in brewing, 31–32
Tasting panel comparison results, 68–69, 69, 70, 70, 71
Temperature
and color levels for classic malt types, 43
for extraction of undesirable compounds, 52
freezing point of beer, 150, 150, 151, 151, 152
yeast-preferred ranges, 82–83
Terpenes in hops essential oils, 57–59, 60, 61, 62
Thermal loading, definition of, 44
Thickness of mash, 49
Thiols sulfur compounds, 35
T-2-N potential, 137–139
Toffee or caramel flavors in staling of beer, 128
Trace elements, roles in brewing, 36
Trans-2-nonenal (T-2-N), xiv–xv, 137–139
Trisaccharides, 22
UFA. See unsaturated fatty acids (UFA)
Unsaturated fatty acids (UFA), xv, 15, 29–30
Valine, 23
Viennese style beers, 15
Viscosity and standardized worts, 39
Vitamin sources during fermentation, 35–36
“Warm day analysis” of newly bottled beer, 143, 143, 144
Water
solvency of, 2
Wheat
β-glucans level, 21
for brewing, 45
Windisch-Kolbach (⁄W-K) units, 42–43
Wine yeasts, 85–86
°W-K
See Windisch-Kolbach units, 42–43
Wort
amino acids assimilated by yeast in fermentation, 100–101
attenuation in yeast flocculation, 80–81
carbohydrate content of, 26
chilling of, 28
clarity of, 30
“cold break,” 78
coliform bacteria spoilers, 123, 123, 124, 124, 125, 125
composition of, xiii
evaporation rates and flavors, 77–78
free amino nitrogen (FAN) amino acid content of, 26
importance of carbonate/bicarbonate, 5, 7
nitrogen levels of, 28–29
oxygenation of, xii
production/reduction of dimethyl sulfide (DMS), 71–75
protein coagulation “hot break,” 78
proteins, content of, 23
pyrroles as flavor source, 77
Wort, boiling of
hops, resins and essential oils, 53–59
isomerization of hop compounds, 65–67
oxidation/polymerization of hop resins and oils, 67–69, 69, 70, 70, 71
oxygen-bearing components, 59, 63–64
selected hops data, 60, 61, 62
sulfur-containing compounds, 64–65
W-308 yeast strain, 84
Xylose, 21
Yeast-active fining agents, 148, 149
Yeasts
behavioral characteristics of, 80–83, 83, 84
birth-scar theory of multiplication, 86–89
“bottom cropping” of, 81
care and feeding of brewing strains, xii, 86–89
classification of, 79–80
contaminated types, 84–86
ester signature flavors, 111–112, 112, 113
individual strains, xiii
metabolism and phenolic compounds, 32
number of yeast cells, xii
oxygen demands, 81–82
physiological condition of, xii, xiii
pitching considerations, 81–83, 83
preferred temperature ranges, 82–83
reusing of, 86–89
“rousing” of, 81
sensitivity to alcohol, 81
strains affected by the Crabtree effect, 94
sugar-fermenting abilities, 81–83, 83
super attenuating types, 84–85
wine yeasts, 85–86
Zinc, yeast requirements for, 36
Zymomonas bacteria in fermentation, 124