Improvement of the quality of soy sauce by reducing enzyme activity in Aspergillus oryzae.
Food Chem. 2019 Sep 15;292:81-89
Authors: Ding C, Meng M, Jiang Y, Hou L
How to effectively increase or decrease the ability of A. oryzae to produce enzymes was the key to improve the quality of soy sauce. However, multi-core property of A. oryzae resulted in genetic instability of the new strain. Here, A. oryzae 3.042-3 which can stably produce mononuclear spores was constructed based on A. oryzae 3.042. A. oryzae 3.042-3-c obtained by transformation of the fragment of cis-CreA into A. oryzae 3.042-3 exhibited genetic stability. The fragment containing the cis-acting and the promoter CreA from A. oryzae was connected to chromosome VII in A. oryzae 3.042-3-c. Compared with A. oryzae 3.042-3, the cellulase activity of A. oryzae 3.042-3-c was reduced by 50.5% and the pectinase activity was decreased by 10.0%. At the end of the soy sauce fermentation, the salt-free solid content of A. oryzae 3.042-3-c was higher 58.9% than that of A. oryzae 3.042-3. The kinds and contents of the flavor components of the soy sauce from the fermentation by A. oryzae 3.042-3-c were higher than those of the A. oryzae 3.042 and A. oryzae 3.042-3, especially in alcohols and esters. HEMF was only found in the soy sauce from A. oryzae 3.042-3-c. The results indicated that the new strain A. oryzae 3.042-3-c could improve the quality of soy sauce from the low-salt solid fermentation by decreasing enzyme activity of cellulase and pectinase.
PMID: 31054696 [PubMed – in process]