2009_Book_FoodChemistry

2.7 Enzyme Utilization in the Food Industry 151
Table 2.22. Peptidases (proteinases) utilized in food processing
Name Source pH Optimal
optimum stability
pH range
A. Peptidases of
animal origin
Pancreatic
proteinase a Pancreas 9.0 b 3–5
Pepsin Gastric lining of swine or bovine 2
Chymosin
Papain
Stomach lining of calves
or genetically engineered
microorganisms B. Peptidases of 6–7 5.5–6.0
plant origin
Tropical melon tree
(Carica papaya) 7–8 4.5–6.5
Bromelain Pineapple (fruit and stalk) 7–8
Ficin Figs (Ficus carica) 7–8
C. Bacterial peptidases
Alkaline
proteinases
e. g. subtilisin Bacillus subtilis 7–11 7.5–9.5
Neutral
proteinases
e. g. thermolysin
Bacillus thermoproteolyticus 6–9 6–8
Pronase
Streptomyces griseus
D. Fungal peptidases
Acid proteinase Aspergillus oryzae 3.0–4.0 d 5
Neutral
proteinase Aspergillus oryzae 5.5–7.5 d 7.0
Alkaline
proteinase Aspergillus oryzae 6.0–9.5 d 7–8
Proteinase Mucor pussillus 3.5–4.5 d 3–6
Proteinase Rhizopus chinensis 5.0 3.8–6.5
a A mixture of trypsin, chymotrypsin, and various peptidases with amylase and lipase as accompanying enzymes.
b With casein as a substrate.
c A mixture of various endo- and exopeptidases including amino- and carboxypeptidases.
d With hemoglobin as as substrate.
by adding Ca 2⊕ ions. α-Amylases added to the
wort in the beer production process accelerate
starch degradation. These enzymes are also used
in the baking industry (cf. 15.4.1.4.8).
2.7.2.2.3 Glucan-1,4-α-D-Glucosidase
(Glucoamylase)
Glucoamylase cleaves β-D-glucose units from the
non-reducing end of an 1,4-α-D-glucan. The α-
1,6-branching bond present in amylo-pectin is
cleaved at a rate about 30 times slower than the α-
1,4-linkages occurring in straight chains. The enzyme
preparation is produced from bacterial and
fungal cultures. The removal of transglucosidase
enzymes which catalyze, for example, the transfer
of glucose to maltose, thus lowerung the yield
of glucose in the starch saccharification process,
is important in the production of glucoamy-lase.
The starch saccharification process is illustrated
in Fig. 2.50. In a purely enzymatic process
(left side of the figure), the swelling and gelatinization
and liquefaction of starch can occur
in a single step using heat-stable bacterial
α-amylase (cf. 2.7.2.2.2). The action of amylases