Horáčková Š., Mühlhansová A., Sluková M., Schulzová V., Plocková M. (2015): Fermentation of soymilk by yoghurt and bifidobacteria strains. Czech J. Food Sci., 33: 313-319.Soy and milk based products fermented by yoghurt culture YC-381 alone or in combination with two probiotic cultures (Bifidobacterium animalis subsp. lactis BB 12 and Bifidobacterium bifidum CCDM 94) were prepared. Bacteria growth, the amounts of lactic acid, acetic acid, and acetaldehyde were compared after 16 h of fermentation at 37°C. The changes of isoflavones concentrations were also monitored in soy products. The growth of Streptococcus thermophilus and bifidobacteria was similar in both media, but Lactobacillus delbrueckii subsp. bulgaricus showed a better growth in milk. Titratable acidity and the concentrations of acids were consistently higher in cow milk than in soymilk at the end of fermentation. Bifidobacteria, compared to the yoghurt culture, were only able to acidify the media to the half values. Comparing the bifidobacteria strains, Bifidobacterium animalis subsp. lactis BB 12 exhibited a better ability to acidify milk. The strain Bifidobacterium bifidum CCDM 94 was able to release 6.90 mg/100 ml of isoflavone aglycones in soymilk.

Conventional quantifi cation of L. helveticus, in presence of other lactobacilli species, using classical plate method employing low selective media is very inaccurate. Determination of L. helveticus using quantitative PCR (qPCR) was performed in six artisanal Kazakh soft cheeses made from cow's milk or from a mixture of cow's and goat's milk. L. helveticus was quantifi ed by species-specifi c qPCR, monitoring the presence of genes encoding for peptidoglycan hydrolases. Quantifi cation of L. helveticus based on qPCR ranged from 2.6×10 6 to 4.1×10 8 CFU·g -1according to the type of the cheese. The microfl ora of cheese consisted of a mixture of starter and non-starter lactic acid bacteria.