Changes in protein during manufacture of miso and fermented soybean using the fungus of
Aspergillus and
Rhizopus were examined by SDS-polyacrylamide gel electrophoresis.
1. Protease activity, especially that of
Rhizopus, was largely inactivated by ethanol in non-salt miso containing 5% ethanol.
2.
Aspergillus protease activity measured at pH 3.0 and 6.0 remained more than 80 and 90%, respectively, in miso containing 4 to 12% salt and fermented for60 days, whereas Rhizopus protease remained 70 and 80%, respectively.
3. Solubilization and hydrolysis ratio of protein in miso by
Rhizopus were lower than those in
Aspergillus miso.
4. Protein with molecular weight higher than 40, 000 almost disappeared in Aspergillus miso for 30 days, whereas it remained in
Rhizopus miso even after 60 days.
5. Bands of molecular weight about 10, 000 in the gel faded gradually in
Aspergillus miso after 10 days, but they maintained dense color in
Rhizopus miso for longer period.
6. Bands of molecular weight 50, 000 to 70, 000 vanished completely and those near 10, 000 increased in fermented soybean by
Aspergillus.
7. Bands of molecular weight higher than 20, 000 did not show any remarkable change and those near 10, 000 became slightly dense in fermented soybean by
Rhizopus.
8.
Aspergillus hydrolyzed soybean protein to products of low molecular weight, whereas Rhizopus slightly hydrolyzed it leaving the most part as middle and high molecular weight substances.
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