Research on strategies for improving the quality of soy sauce seed koji

Using Aspergillus oryzae 3.042 as the research object, the effects of different carbon sources, nitrogen sources, and inorganic salts on the quality of soy sauce seed koji were investigated by using spore production, hydrophobicity, trehalose content, and spore germination rate as the evaluation indicators. The results showed that glucose could increase the spore production, hydrophobicity and trehalose content of A. oryzae. Adding 5 g/kg of glucose (calculated by carbon element) could increase the spore numbers in seed koji by 34%. Ammonium sulfate, potassium dihydrogen phosphate and sodium dihydrogen phosphate could increase the spore number, hydrophobicity and germination rate of seed koji. Adding 3 g/kg of ammonium sulfate, the spore numbers of seed koji increased by 23% and the germination rate increased by 15 times. Adding 3 g/kg of potassium dihydrogen phosphate, the spore numbers of seed koji increased by 15% and the germination rate increased by 2 times. Adding 3 g/kg of sodium dihydrogen phosphate, the spore numbers of seed koji increased by 13% and the germination rate increased by 1.5-2.0 times.