H������� M., F��������� V., R����� P., P�������� M. (2004): Biosynthesis of folates by lactic acid bacteria and propionibacteria in fermented milk. Czech J. Food Sci., 22: 175-181.Folate producing ability of several strains of Bifidobacterium longum, Bifidobacterium bifidum, Streptococcus thermophilus and Propionibacterium freudenreichii subsp. shermanii was evaluated. As substrate, UHT milk with 1.5% fat content treated with additional laboratory sterilisation was used. Fermentation was conducted at 37°C and 30°C in the case of Propionibacterium. 5-Methyltetrahydrofolate (5-MTHF) concentrations were determined using HPLC method. All strains of Streptococcus thermophilus tested showed 5-MTHF production. More than six-fold increase was found in the 5-MTHF content in comparison with control (increase = 3.69 µg 5-MTHF/100 g) after 12 h fermentation. Bifidobacterium longum strains were recognised as mild folate producers with max. 73% increase in the 5-MTHF content (increase = 0.48 µg 5-MTHF/100 g) after 12 h fermentation. The Propionibacterium freudenreichii subsp. shermanii strains tested did not basically influence the 5-MTHF levels during milk fermentation. In all cases, maximum 5-MTHF concentration was reached between 6 and 12 hours of fermentation. Large differences in the 5-MTHF production were found among individual strains within species. By a careful testing of the folate production ability of microbial strains used in the production of fermented milk, an enhancement of the natural folate content can be achieved.

Nmeková I., Dragounová H., Pechaová M., Rysová J., Roubal P. (2011) People suffering from lactose intolerance, cow's milk allergy or phenylketonuria or people on low-protein diet are restricted in the consumption of dairy products. Their consumers' basket should be variegated and enriched with probiotics. The main task was to evaluate important growth and metabolic characteristics of lactic acid bacteria in rice, natural rice, corn, chickpea and barley. Suspensions of the respective flours in water (8% w/w) were supplemented with glucose (1% w/w), pasteurised and fermented. Suitable combinations of cultures and substrates enable the growth of microorganisms minimally by t 2 decimal orders. This is connected with a specific shape of the acidification curve pH should be higher than 4.5 after 4-h fermentation. The vegetable samples contained lower concentrations of organic acids than milk samples because of their lower contents of the buffering substances. Fermentation did not result in any decrease in the concentration of protein or phenylalanine. Thus, special formulas of foods for people on phenylketonuria diet or low-protein diets should be conceived. Fermentation of vegetable substrates seems to be a prospective technology in functional foods manufacturing.

The possibility of the increase of the natural folate content in fermented milk products by the fermentation process and by the addition of fruit component was evaluated. 5-methyltetrahydrofolate (5-MTHF) content was followed after the inoculation of pasteurised milk with the butter starter and the selected strains of Streptococcus thermophilus in combination with Bifidobacterium longum or Propionibacterium freudenreichii subsp. shermanii followed by fermentation at 30°C and 37°C for 12 and 18 h. 5-MTHF was determined by HPLC method after deconjugation with hog kidney conjugase and SPE SAX purification. The highest 5-MTHF content increase of 4.03 ± 0.44 µg/100 g was found at cofermentation with Streptococcus thermophilus No. 144 and Propionibacterium freudenreichii subsp. shermanii No. 160 at 37°C after 12 h of fermentation. 9 commercial fruit components used in dairy industry contained between 0.17–9.11 µg 5-MTHF/100 g. The components produced with pineapple, sour cherry, apricot, and apple contained low amounts of 5-MTHF – less than 1 µg/100 g. Among the rest of the components tested, the strawberry component proved to be the best source of folate with the content of 9.11 µg 5-MTHF/100 g. The values in 7 varieties of fresh fully ripe strawberries fluctuated between 25.5 and 54.0 µg/100 g fresh sample, i.e. 272 and 554 µg/100 g dry matter with the highest content found in the varieties Elsanta and Honeyoe. Fully ripe berries of the variety Senga Sengana contained by 63% more 5-MTHF in comparison with unripe berries. In order to reach maximum folate content in the fruit component, fully ripe strawberries of the cultivars Elsanta and Honeyoe are recommended for the processing. The folate content in the fermented milk product may be increased in this way by 4.8 µg/100 g, with 69% originating from the fermentation and 31% from the fruit component addition.  

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