대두유 중에서 Lactobacillus sp.와 Yeast의 혼합배양에 관한 연구 : (제 1 보) Yeast starter의 선정 Part 1. selection of Yeast starter = Studies on the Mixed culture of Lactobacillus sp. and Yeast in soymilk

다국어 초록 (Multilingual Abstract)

Since fermentation often improves or modifies flavor, taste and texture of soybean, attempts have been made develop fermented products from soymilk by using Lactic Acid Bacteria and methods employed in fermenting cow's milk.
However no acceptable product has resulted from soymilk by these Lactic Acid Bacteria and conventional methods alone.
Nevertheless, there is no published information on the behavior of the mixed cultuure of Lactobacillus sp. and Yeast in soymilk.
The purpose of this study was to develop the mixed culture system of Lactobacillus sp. and Yeast suitable for preparation of the fermented soymilk with acceptable flavor, Yogurt-like texture and low content of flatulence causing galacto oligosaccharides.
The fermentable carbohydrates in soybean and soybean products are low molecular weight oligosaccharides such as sucrose, Raffinose, stachyose.
Raffinose, stachyose are known to be flatulence causing oligosaccharides.
However, some species of Lactobacillus employed in fermenting cows milk such as L. bulgaricus, L.acidophilus, L. casei cannot utilize these flatulence causing oligosaccharides and show little Growth in soymilk.
Therefore, the selection of yeast strains possessing the ability to utilize these galacto oligosaccharides and simultaneously to stimulate the growth and acid production of these Lactobacilli in soymilk is essential if they are to be used in preparation of fermented product from soymilk.
Consequently, selection of suitable Yeast strains for making fermented soymilk was carried out using 5 saccharomyces cerevisiae strains, and 4 kluyveromyces fragilis strains.
Most of Yeast strains used for selection test grew well in soywhey.
High perforniance Liquid chromatography (HPLC) was utilized for profile comparison Analysis to determine the extent of utilization of oligosaccharides found in suywhey and soymilk by test strains of yeast.
All 9 strains of Yeast used for selection test hydrolized sucrose, Raffinose in soywhey and soymilk during 48hr of incubation at 37℃. saccharomyces cerevisiae IFO 0216 and kluyveromyces fragilis IFO 1963 among the test strains of Yeast completely hydrolized Raffinose and stachyose by 16hr during fermenting of soywhey at 37℃
Fructose appeared early during the incubation and increased in concentration with time (0∼12hr) but decreased slightly thereafter, whereas melibiose and manninotriose also appeared after 12∼16hr of fermentation of soywhey and soymilk with 5 test strains of Yeast at 37℃
Acid production (Growth) of all species of Lactobacillus and s.lactis used for experiments was confirmed to be stimulated by added cell Free Filtrate of saccharomyces cerevisiae IFO 0216 and kluyveromyces fragilis IFO 1963, respectively.
The cell Free Filtrate of kluyveromyces fragilis IFO 1963, had better stimulatory effect on Acid production of some species of Lactobacillus than that of saccharomyces cerevisiae IFO 0216 had.
The results of this investigation indicate that fermentation of soymilk with Yeast strains can be used to reduce Raffinose and starhyose contents which are belived to contribute to flatulent properties of soybean.