Food Chemistry

902 20 Alcoholic Beverages

Thus, for example, if the solids content (E) of
a beer is 3% (w/v) and the alcohol content (A)
is 5.0% (v/v), then the solids content of the wort
before fermentation was 12.6% (w/v). The stem-
wort content in Germany is 2–5.5% for plain
beers, 7–8% for draft beers, 11–14% for full beers
and above 16% for strong beers.

20.1.7.3 Acids

Carbon dioxide is responsible to a substantial
extent for the refreshing value and stability of
beer. CO 2 is 0.36–0.44% in bottom fermented
beers, while in Weiss beer the CO 2 content is
up to 0.6–0.7%. A CO 2 content below 0.2%
gives flat and dull beers. Apart from small
amounts of lactic, acetic, formic, and succinic
acids, beer contains 9,10,13- and 9,12,13-tri-
hydroxyoctadecenoic acid. In fact, 9. 9 ± 2 .1mg/l
were found in five types of beer and 9(S), 12(S),
13(S)-trihydroxy-10(E)-octadecenoic acid was
the main compound and accounted for 50–55% of
the 16 stereoisomers. The pH of beer is between
4 .7 (dark, strong beer) and 4.1 (Weiss beer).

20.1.7.4 Nitrogen Compounds

The N-compounds in beer (0.15–0.75%) origi-
nate primarily from proteins in the raw materials
and from yeast. They consist mainly of proteins
plus high molecular weight protein degradation
products; both being responsible for cloudiness
in beer during cold storage. The free amino acids
found in malt are also present in beer. It appears
that glutamic acid contributes to beer taste. The
presence of volatile amines has also been con-
firmed.

20.1.7.5 Carbohydrates

The carbohydrate content is approximately
3–5%, while in some strong beers or malt beers
it may be considerably higher. Pentosans are
also present in addition to dextrins, mono- and
oligosaccharides (maltotriose, maltose, etc.).
Glycerol normally is 0.2–0.3% of beer.

20.1.7.6 Minerals

Minerals make up 0.3–0.4% of beer and con-

sist mostly of potassium and phosphate. Calcium,

magnesium, iron, chloride, sulfate and silicates

are also present.

20.1.7.7 Vitamins

Vitamins of the B-group (vitamins B 1 and B 2 ,

nicotinic acid, pyridoxine and pantothenic acid)

are present in various beers, often in significant

amounts.

20.1.7.8 Aroma Substances

The odorants, e. g., for Pilsener beer are shown in

Table 20.6. The aroma is reproduced by a suitable

mixture of these substances dissolved in water,

the pH of which is adjusted to 4.3 with carbonic

acid. This emphasizes the fact that the key odor-

ants of this type of beer can be analytically iden-

tified. (R)-Linalool and ethyl-4-methylpentanoate

are derived from hops and pass into the beer on

boiling the wort.

The odor- and taste-active substances essentially

determine the type of beer. The bitter taste of

Pilsener beers is produced by relatively high con-

centrations of isohumulons, and humulenes (in-

cluding oxidation products), while larger amounts

of furaneol are responsible for the caramel note of

dark beers.

In the production of alcohol-free beer, the con-

centrations of important aroma substances drop

(Table 20.7).

20.1.7.9 Foam Builders

The foam building properties of beer are due to

proteins, polysaccharides and bitter constituents.

Theβ-glucans stabilize thefoam through their

ability to increase viscosity. Addition of semisyn-

thetic polysaccharides, e. g., propyleneglycol al-

ginate (40 g/hectoliter), to beer provides a very

stable foam although the addition is judged as un-

favorable.