engleski

Influence of temperature and glucose addition on growth and survival of bacteria from BCT culture in soymilk

Soymilk was fermented using culture composed of Lactobacillus casei, Bifidobacterium spp. and Streptococcus thermophilus (BCT culture, Chr. Hansen’ s, Denmark) at two temperatures 37 and 41°C with and without 5 percent of glucose addition. Fermentation was conducted until pH value 4.6 was reached. During the fermentation and storage time (28 days at +4°C) the changes of pH values and viable cells counts were observed. All fermentations lasted between 6 and 7.5 hours. At temperature 41°C fermentation was approximately 1 hour shorter, while glucose addition had reduced fermentation time for 30 minutes. Higher temperature of fermentation, as well as glucose addition, had negligible influence on portions and viable cells count of particular bacterial species in the product. In all fermented soymilk samples the viable cells count of particular bacterial strains was roughly equal: Str. thermophilus have grown the best (~ 10exp8 CFU/mL) while lactobacilli have grown the weakest (~ 10exp5-10exp6 CFU/mL). Generally, for soymilk fermentation mainly Str. thermophilus was responsible. On its growth rate glucose addition and higher temperature of fermentation had strong positive influence. During the 28 days of refrigerated storage, the product was stable. A remarkable decrease of viable cells count of lactobacilli was noticed in the last week of storage.

soymilk ; Bifidobacterium spp. ; Lactobacillus casei ; Streptococcus thermophilus ; fermentation

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