Food Chemistry

906 20 Alcoholic Beverages

Table 20.8.Main characteristics of the odor and taste of various types of beer

Flavor group Intensitya

Munich Pilsner Pale ale US lager Stoutb Lambic

Bitterness 3–6 6–10 5–8 2–4 6–10 3–6
Alcoholic flavor 2–4 3–4 3–4 3–5 3–5 3–6
Carbonation 3–4 3–4 1–3 4 3–4 3–5
Hop character 2–6 6–10 5–8 0 .5–4 6–10 3–6
Caramel flavor 4–8 0 .5–2 3–5 0 .5–1 6–100 1–3
Fruity/estery flavor 1–2 1–1.5 1–2 2–3 2–3 3–5
Sweetness 2–3 1–2 1–2 2–3 1–2 1–2
Acidity 1–2 1–2 1–2 1–2 2–3 3–20
Cabbage-like 1–2 1–3 0 .2–0. 8 1–3 0 .2–0. 8 1–10

aSemiquantitative values on the basis of aroma values.
bTop fermented English strong beer with a stemwort content of up to 25%.

2-buten-l-thiol (cf. Table 5.5). This substance be-
comes unpleasantly noticeable at concentrations
higher than 0.3μg/l. It is one of the character-
istic aroma substances below this concentration.
Enzymatic peroxidation of lipids contained in the
wort and nonenzymatic secondary reactions dur-
ing wort boiling give rise to the aroma defects
listed as No. 8 in Fig. 20.3.
A sweetish off-flavor formed during storage
of beer is caused by an increase in 3-methyl-
butanal, methional, phenylacetaldehyde, ethyl
methylpropanoate and ethyl 2-methylbutanoate.
The addition of ascorbic acid or glucose oxi-
dase/catalase (cf. 2.7.2.1.1) is recommended to
overcome color and flavor defects caused by oxi-
dation. Therefore, low-oxygen bottling is of great
importance. Bottled beer should not contain more
than 1 mgO 2 /l.
Unwanted carbonyl compounds, which can pro-
duce an off-flavor in stored beer, are bound by sul-
fite derived from yeast metabolism. Yeast reduces
the sulfate present in the wort to sulfite and sul-
fide, which is then consumed in the biosynthesis
of sulfur-containing amino acids. If the growth of
yeast comes to a standstill, excess sulfite is elim-
inated, increasing the stability of the beer to ox-
idative processes.
The very potent aroma substance 3-methyl-3-
mercaptobutyl formate (cf. 5.3.2.5) can produce
an off-aroma called “catty” (0810 in Fig. 20.3).
The concentration of phenylacetaldehyde can
also increase to such an extent on the stor-
age of beer that it becomes noticeable in the
aroma.

On storage, beer can become cloudy and form

a sediment. Proteins and polypeptides make up

40–75% of the turbidity-causing solids. They

become insoluble due to the formation of inter-

molecular disulfide bonds, complex formation

with polyphenols, or reactions with heavy metals

ions (Cu, Fe, Sn). Other components of the

sediment are carbohydrates (2–25%), mainly

α-andβ-glucans. For measures used to prevent

cloudiness, see 20.1.8.5. Undesirable microor-

ganisms, e. g., thermophilic lactic acid bacteria,

acetic acid bacteria (Acetobacter, Gluconobacter)

and yeasts, can cause disturbances and defects

in various process steps (mashing, fermentation,

finished product).

20.2 Wine

20.2.1 Foreword

Wine is a beverage obtained by full or partial

alcoholic fermentation of fresh, crushed grapes

or grape juice (must). The woody vine grape

has thrived in the Mediterranean region since

ancient times and Italy, France and Spain are

still among the leading wine-producing countries

in the world. Other major producers are USA,

Argentina, Chile, Germany and South Africa.

Table 20.9 provides data on wine production and

consumption in some countries. An overview of

the individual process steps in wine production is

presented in Fig. 20.4.