Food Chemistry

152 2 Enzymes

Fig. 2.49.The activity ofα-amylase as influenced by
temperature. 1α-amylase fromBacillus subtilis, 2 from
Bacillus licheniformis

Fig. 2.50.Enzymatic starch degradation

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 brew-
ing process and in starch hydrolysis. In combi-
nation withβ-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 in-
crease wort viscosity and impede filtration. Enzy-

matic endo-hydrolysis reduces viscosity.

2.7.2.2.6 α-D-Galactosidase.......................................

This and the following enzymes (up to and in-

cluding section 2.7.2.2.9) attack the non-reducing

ends of di-, oligo- and polysaccharides with re-

lease of the terminal monosaccharide. The sub-

strate specificity is revealed by the name of the

enzyme, e. g.,α-D-galactosidase:

(2.111)

In the production of sucrose from sugar beets

(cf. 19.1.4.1.2), the enzymatic preparation from

Mortiella vinaceahydrolyzes raffinose and, thus,

improves the yield of granular sugar in the crys-

tallization step. Raffinose in amounts>8% effec-

tively prevents crystallization of sucrose.

Gas production (flatulence) in the stomach or in-

testines produced by legumes originates from the

sugar stachyose (cf. 16.2.5). When this tetrasac-

charide is cleaved byα-D-galactosidase, flatu-

lency from this source is eliminated.

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-