Using propionibacteria cultures for folacine fortification of sauerkraut

Propionibacteria are able to synthetize, during biological preservation, vitamin B12 and folacine in symbiosis with the yeast Kluyveromyces fragilis in nutrient media. This ability of the propionibacteria was used in the study for nutritive enrichment of foodstuffs. The objective of the study was to compare the pattern of biosynthesis of folacine, the pH values and sensory characteristics (appearance, colour, taste, flavour, consistence) in the model samples of fermented cabbage during fermentation (20+-2 degrees C, 8 days) and storage (35 and 43 days) under varying conditions. The samples were artificially inoculated with the bacteria Propionibacterium jensenii and Propionibacterium shermanii. Folacine was determined by the microbiological method. The sensory assessment was performed with the use of a five-point scale. The results of folacine concentration were statistically processed and converted to values per the edible portion and dry matter. Trial 1 was aimed at investigating the biosynthesis of folacine by the P. jensenii during the fermentation and storage of model samples of sauerkraut. Samples for microbiological determination of folacine, for pH determination and sensory assessment were taken on the 1st, 5th, 9th, 23rd, 35th and 43rd days of fermentation and storage under laboratory conditions (20+-2 degrees C). In the second trial, folacine production by P. shermanii was studied during sauerkraut model sample fermentation and storage. The samples for the determination were taken on the 1st, 4th, 8th, 15th, 27th and 35th days of fermentation and storage under chilling conditions (+4 degrees C). The comparison of the biosynthetic characteristics of both strains clearly shows that the use of P. shermanii is more suitable: it increased folacine concentration in the model samples of sauerkraut to an almost three-fold level (287 per cent), compared with the initial raw material. As to the sensory evaluation, the sauerkraut inoculated with the last-mentioned culture had a better colour, a more pronounced taste and a better consistence, and maintained these qualities until the end of storage.