KALFIRTOVÁ P., SOVJÁK R.
Abstract
Over past five years the range of dairy products enriched with added vitamins has grown dramatically. The consumers apply for vitamin enriched dairy products. Food plus refers to category of value-added products that provide health benefits beyond basic nutrition through the inclusion of new or increased levels of key ingredients.
The study is a part of the ,,Nutra Cells" large European research project which is investigated the possibility of the vitamin B12 production by the new strain of Propionibacteria freudenreichii ssp. shermanii. The company where the research was realized have been quick to recognize the importance of the fortified dairy products and are also trying the new ways to obtain increased level of vitamins in dairy products.
The samples of yoghurt incorporated in different concentration 1% (v/v) and 5% (v/v) and different medium Lactate and Milk preculture with Propionibacterium freudenreichii ssp. shermanii B 374-2, was tasted and compared with BY 330 (reference yoghurt), basic Lactate and Milk preculture and Milk. The samples were measured at the beginning of fermentation (t = 0), in the end (t = 4,5 pH) and after 14 days of storage at 4 C in two independent yoghurt trials.The presence and the growth of Propionibacterium freudenreichii ssp. shermanii B 374-2,2 during the fermentation and after storage at 4 C was monitored by counting of CFU´s in Lactate medium in duplicate measurements. Vitamin B12 was determined by a Microbiological Bio-assay with indicator strain Lactobacillus delbrueckii ssp. leichmanii.
In conclusion, it is possible to say that the new strain of Propionibacterium freudenreichii ssp. shermanii was proved like a very good producer of vitamin B12 during yoghurt fermentation and storage at 4 C and therefore it can be used to fortify dairy products.
Key words:
fermented dairy products, healthful food, Nutraceuticals, Propionibacterium freudenreichii ssp. shermanii, Vitamin B12, Microbiological Bio-assay.