Food Chemistry

20 Alcoholic Beverages

Alcoholic beverages are produced from sugar-
containing liquids by alcoholic fermentation.
Sugars, fermentable by yeasts, are either present
as such or are generated from the raw material
by processing, i. e. by hydrolytic cleavage of
starches and dextrins, yielding simple sugars.
The most important alcoholic beverages are beer,
wine and brandy. Beer and wine were known to
early civilizations and were produced by a well-
developed industry. The distillation process for
liquor production was introduced much later.
The nutritional energy value of ethanol is high

(29 kJ/g or 7 kcal/g).
Figure 20.1 illustrates theEmbden–Meyerhoff–
Parnasscheme of alcoholic fermentation and gly-
colysis. For related details about the reactions and
enzymes involved, the reader is referred to a text-
book of biochemistry.

20.1 Beer

20.1.1 Foreword

Beer making or brewing involves the use of ger-
minated barley (malt), hops, yeast and water. In
addition to malt from barley, other starch- and/or
sugar-containing raw materials have a role, e. g.,
other kinds of malt such as wheat, unmalted cer-
eals called adjuncts (barley, wheat, corn, rice),
starch flour, starch degradation products and fer-
mentable sugars. The use of additional raw mate-
rials may necessitate in part the use of microbial
enzyme preparations.
Beer owes its invigorating and intoxicating
properties to ethanol; its aroma, flavor and bitter
taste to hops, kiln-dried products and aroma
constituents formed during fermentation; its
nutritional value to the content of unfermented
solubilized extracts (carbohydrates, protein);
and, lastly, its refreshing effect to carbon dioxide,
a major constituent. Data on beer production

and consumption are given in Table 20.1 and

a schematic representation of the production of

beer is given in Fig. 20.2.

20.1.2 Raw Materials

20.1.2.1 Barley

Barley is the most important of the raw materi-

als used for beer production. Different cultivars

of the spring barley (Hordeum vulgare convar.

distichon) with exceptionally suitable properties

are used as brewing and malting barley in Ger-

many. In addition, six-row winter barley has an

increasing role. Barley of high brewing value pro-

vides ample quantities of extract from the resul-

tant malt, and has a high starch but moderate pro-

tein (9–10%) content, a high degree of germina-

tion (at least 95% of kernels), high germination

vigor and good swelling ability. Sensory assay

(hand appraisal) should also be included in the

evaluation of a barley.

20.1.2.2 Other Starch- and Sugar-Containing

Raw Materials

20.1.2.2.1 Wheat Malt

Wheat malt is mixed with barley malt in a ratio of

40:60 in the production of top fermented beer.

20.1.2.2.2 Adjuncts

In addition to barley malt, supplementary sources

of starch are used in the form of unmalted cer-

eals (adjuncts) in order to dilute the mash by 15–

50%. The adjuncts are barley, wheat, corn and

rice (cracked rice) in the form of whole meal,

grits, flakes or flour.

H.-D. Belitz · W. Grosch · P. Schieberle,Food Chemistry 892
© Springer 2009