Isolation of Halotorelant Yeasts capable of Assimilating Linoleate in Miso

Studies on lipids of soybean foods (Part VII)

Abstract

The change of fatty acid compositioa of specially prepared miso with yeast starter were investigated and a halotrelant yeast, Saccaromyces rouxii was found to be the principal microorganism capable of assimilating linoleate in miso. The analyses of lipids and fatty acid composition of miso were carried out, employing 7 specially prepared miso in Niigata prefecture and one specially prepared miso in Aomori prefecture. Two samples of Niigata miso showed higher level of linoleate composition in triglyceride fraction by more than 10% that of free fatty acid fraction, indicating that some reduction of linoleate had been taken place during fermentation of miso. Microorganisms were isolated from one of the two Niigata miso and Aomori miso by the plate method. From the results of the isolation and identification of the microorganisms, S. rouxii, Bacillus subtilis and B. pumilus were identified from the former miso, and S. rouxii and S. rouxii var. halomembranis, Bacillus species and Micrococcus species were identified from the latter miso. Linoleate assimilation was detected by oxygen consumption during cultivation in the media including linoleate as a sole carbon source. S. rouxii and one strain of S. rouxii var. halomembranis showed the assimilation clearly. Weak or no significant assimilation was shown by Rhodotorula glutinis var. glutinis and Bacillus sp. The strains, S. rouxii S-96 and S. rouxii 301 which were added in the specially prepared miso also showed high linoleate assimilation.