Utilization of Koji Enzymes and Food Production through Alcoholic SSF of Yeasts

Abstract

1) Production of r-glutamyltranspeptidase using Penicillium koji and its application. Distribution and properties of r-glutamyltranspeptidase (GGT)were investigated in filamentous fungi used for food production. GGT of Penicihium possessed much more transpeptidation activity than hydrolysis activity and exhibited tolerance against NaC1. (The highest procedure of GGT was P. roqueforti IFO 4622 for blue cheese production.) After partial purification, the transpeptidation activity of the enzyme was 12 times as high as hydrolysis and it was activated with a range of 2 to 16% of NaC1. The optimal pH of the enzyme was 8 to 9, and its heat stability was poor. GGT was purified from P. roqueforti (IFO 4622) to a homogeneous protein. The GGT showed much higher transpeptidation activity than hydrolytic activity. The molecular weight was 100,400 and the optimum pH was 8 to 9 both for hydrolysis and for transpeptidation. The enzyme had a poor stability to heat. Various amino compounds could serve as a r-glutamyl acceptor for the enzyme. With 4% NaCl, the enzyme activity was enhaneed to 140% the level without NaCl. Formation of r-glutamyltaurine (r-GluTau) frim L-glutamine and taurine with GGT of P. roqueforti (IFO 4622) was carried out. As the GGT preparation, a wheat bran koji extract prepared with P. riqueforti (IFO 4622) was used. 105mM of rGluTau was formed at a yield of 43% in a reaction mixture containing 250mM L-glutamine, 100mM Tris-HC1 buffer (pH 8.5) and 0.6 unit/ml of the GGT. 2) Cell production of Bifidobacteria using Aspergillus koji cultures. 3) Production of peptide foods through fungal and yeast SSF without salt. We have developed a process for the production of peptide foods by a combination of Aspergillus koji and Saccharomyces cerevisiae in semi-solid state fermentation. The addition of cooked soybeans to mixture of Aspergillus rice koji and starch of sugars without salt, followed by fermentation of S. cerevisiae for several weeks, resulted in 5-10% yields of alcohol and production of preservable peptides. The fermented product was a paste from which alcohol is removed by distillation. The final product can be shipped not only as manufactured foods, but also as intermediate materials for food processing. This method can be applied to fish and livestock products.