文档介绍：9
Malting, Brewing and Distilling
Introduction relevant to the country of origin and the descrip-
tion of the product. Consequently, added enzymes
The essential process involved in brewing is
may contribute different proportions of the enzyme
the conversion of cereal starch into alcohol to
complement.
make a palatable, intoxicating beverage. Fermen-
The alcohol content of the liquor produced by
tation is mediated by yeasts appropriate to the
fermentation is limited by the tolerance of the
cereal or cereals involved. Most yeasts used
yeasts. Probably the most tolerant yeasts are used
belong to the species haromyces cerevisiae,
in sake production. They can survive alcohol
which now includes the ‘bottom yeast’ previ-
contents of about 20% although the product is
ously classified as S. carlsbergensis (Reed and
sold in a diluted form.
Nagodawithana, 1991).
Distillation allows the concentration of alcohol
Two processes are involved: the starch has first
into drinks described as spirits, the special
to be converted to soluble sugars by amylolytic
character of which depends on flavours imparted
enzymes, and second, the sugars have to be
by the processing or added to a distillate, the
fermented to alcohol by enzymes present in yeast.
added flavours usually being extracts from other
In the first process the enzymes may be produced
plant sources.
in the grains themselves (endogenously) or
For alcohol production from plant material,
exogenously, in anisms present. Alter-
sugars must be present, as in fleshy fruits, or
natively they may be added as extracts.
other substrates from which fermentable sugars
The process in which the grain’s own enzymes
can be produced. Starch is such a substrate, so
are employed is known as malting. prises
all cereals can be used for beer production. In
a controlled germination during which enzymes
the West, the monly used cereal is
capa