2009_Book_FoodChemistry

152 2 Enzymes
2.7.2.2.6 α-D-Galactosidase
This and the following enzymes (up to and including
section 2.7.2.2.9) attack the non-reducing
ends of di-, oligo- and polysaccharides with release
of the terminal monosaccharide. The substrate
specificity is revealed by the name of the
enzyme, e. g., α-D-galactosidase:
Fig. 2.49. The activity of α-amylase as influenced by
temperature. 1 α-amylase from Bacillus subtilis, 2 from
Bacillus licheniformis
(2.111)
Fig. 2.50. Enzymatic starch degradation
In the production of sucrose from sugar beets
(cf. 19.1.4.1.2), the enzymatic preparation from
Mortiella vinacea hydrolyzes raffinose and, thus,
improves the yield of granular sugar in the crystallization
step. Raffinose in amounts >8% effectively
prevents crystallization of sucrose.
Gas production (flatulence) in the stomach or intestines
produced by legumes originates from the
sugar stachyose (cf. 16.2.5). When this tetrasaccharide
is cleaved by α-D-galactosidase, flatulency
from this source is eliminated.
yields starch syrup which is a mixture of glucose,
maltose and dextrins (cf. 19.1.4.3.2).
2.7.2.2.4 Pullulanase (Isoamylase)
Pullulanase (cf. 4.4.5.1.4) is utilized in the brewing
process and in starch hydrolysis. In combination
with β-amylase, it is possible to produce
a starch sirup with a high maltose content.
2.7.2.2.5 Endo-1,3(4)-β-D-Glucanase
In the brewing process, β-glucans from barley increase
wort viscosity and impede filtration. Enzymatic
endo-hydrolysis reduces viscosity.
2.7.2.2.7 β-D-Galactosidase (Lactase)
Enzyme preparations from fungi (Aspergillus
niger) or from yeast are used in the dairy industry
to hydrolyze lactose. Immobilized enzymes
are applied to produce milk suitable for people
suffering from lactose malabsorption. Milk
treated in this way can also be used to make
products like skim milk concentrate or ice cream,
thus avoiding interference by lactose due to its
low solubility.
2.7.2.2.8 β-D-Fructofuranosidase (Invertase)
Enzyme preparations isolated from special yeast
strains are used for saccharose (sucrose) inver-