2009_Book_FoodChemistry

20 Alcoholic Beverages
Alcoholic beverages are produced from sugarcontaining
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 welldeveloped
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 the Embden–Meyerhoff–
Parnas scheme of alcoholic fermentation and glycolysis.
For related details about the reactions and
enzymes involved, the reader is referred to a textbook
of biochemistry.
20.1 Beer
20.1.1 Foreword
Beer making or brewing involves the use of germinated
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 cereals
called adjuncts (barley, wheat, corn, rice),
starch flour, starch degradation products and fermentable
sugars. The use of additional raw materials
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 materials
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 Germany.
In addition, six-row winter barley has an
increasing role. Barley of high brewing value provides
ample quantities of extract from the resultant
malt, and has a high starch but moderate protein
(9–10%) content, a high degree of germination
(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 cereals
(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