Because of the increasing demand on starch.hydrolyzing enzymes, this
study was focused on studying factors controlling the production of c-arnylase, p.
amylase and glucoamylase from Aspergillus niger M2 and also to study the effect of
these enzyme on quality of balady bread and its staling properties. Spent brewing
grain (SBG). was used as a solid substrate for the production of these enzymes.
Different agro-industrial by-producls were tested for the production of a. p and
glucoamylase. Maximum amylases yields, n, p and glucoamylase synthesis by A.
niger Mz strain were 770. 390 and 950 IU/g dry substrate (g/ds), respectively. These
values were obtained on the optimized media after 96 hrs and suitable conditions of
initial moisture, inoculum size, initial pH and incubation temperature of 65%, 105
spores/gds, 5.0 and 30 "C, respectively. Maltose induced the enzymes biosynthesis
and glucose syrup supported the enzymes formation. Amylases production were
stimulated at 3.0% of glucose syrup. Corn steep liquor (CSL) at 0.21 % as N gave
highest amount of these enzymes. Regarding the dururn wheat starches susceptibility
to A. niger M, glucoamylase enzyme, it was lower than that of soft wheat starches.
This may be due to the highest amylose lipid complexes in durum wheat starch.
Organoliptic evaluation indicated that, durum bread has higher total scores being 87-
97% as compared with soft wheat bread which was 85-86%.Also durum bread has
95·100% of freshness scores, while soft wheat bread has 85-90% of freshness
scores, after' hr of baking. Staling properties expressed as the result of hydrolysis of
crumb bread with A. niger ~ •. h glucoamylase indicated that, after 72 hrs of storage at
room temperature, hydrolysis was in the range of (126.8-137.7 mg gtucose/g crumb).
and (94 ., 07.6 mg glucose/g crumb) in durum and soft bread crumb. respectively.
This means that durum bread has longer shelf life and lower ability to staling
mechanism due to its high content of amylopectin and amylose- lipid-complex.