Browsing by Subject "hyväksikäytettävyys"

The usual dietary sources of vitamin B12 are animal-based foods such as meat, milk, fish and shellfish. Vitamin B12 is an essential water-soluble vitamin for humans, which have many necessary tasks in human body. People who lack animal foods like vegetarians and vegans might be at risk of vitamin B12 deficiency. Microorganisms are the only original sources of vitamin B12 in nature. Especially Propionibacterium freudenreichii synthesizes active form of vitamin B12 for humans. P. freudenreichii is GRAS -graded bacteria and it is safe to use in food matrices. Recently, it has been used for natural fortification of vitamin B12 in plant-based products by fermentation. However, the bioaccessibility of vitamin B12 of those products in human body is not very well known. In the beginning of the study, stability of different B12 vitamers were studied in different light and pH conditions. Vitamin B12 forms are very light-sensitive, especially its physiological forms methyl- and adenosylcobalamin. The aim of this research was to study bioaccessibility of vitamin B12 from P. freudenreichii cells and selected food products using a static in vitro assay. After the in vitro model, vitamin B12 content was analysed with UHPLC system. In addition of bacterial cell samples, bioaccessibility was studied also in some food samples, like bread, pasta and spray-dried powder, fortified with P. freudenreichii cells. In vitamin B12 stability studies, red light seemed to improve the stability of B12 forms. In yellow light methyl- and adenosylcobalamin degraded after 15 minutes. In red light they were detectable after hours of exposure. Methylcobalamin seems to be the most sensitive form of vitamin B12 vitamers. The study revealed that the bioaccessibility of B12 was very small (1,5 %) in P. freudenreichii cells but over 50% in whole bacterial broth. Heat treatment for the samples improved the bioaccessibility to some extent. In B12 fortified food samples, the bioaccessibility of B12 was very good (>70 %). The number of heat treatments and food structure could be one reason why bioaccessibilities in food samples are better than in cell samples. According to this research, in situ fortified food products could be a promising source of vitamin B12 in future.