Assessment of the functional quality and safety of yoghurts produced with starter cultures obtained from selected commercially sold yoghurts

Abstract

The study focused on the examination of laboratory prepared yoghurts which were fermented with selected starter cultures from commercially sold yoghurt. The starter cultures were molecularly identified (16s rRNA) as Enterococcus lactis, Lactobacillus plantarum, Lactobacillus pentosus, Pediococcuspentosaceus and Enterococcus durans. The isolates were examined for bile tolerance as an indicator of their ability to survive in the gut. The starter cultures were used to produce different yoghurts in the following order: Enterococcus lactis produced yoghurt, L. plantarum and L. pentosus produced yoghurt, Pediococcuspentosaceus produced yoghurt, E. durans produced yoghurt and yoghurt produced with all starter cultures. All yoghurts were examined for nutritional quality (vitamin A, B12 and C content, soluble and casein bound magnesium and calcium and proximate nutrient composition). At p ≤0.05, there was statistical significant difference in the nutritional content with P. pentosaceus contained yoghurt, E. durans contained yoghurt and yoghurt produced with a combination of all isolates recording the highest nutritional values and the lowest was observed with the control. Safety tests such as haematology and histology were carried out on wistar rats. After 7 days of feeding the rats in groups with the different yoghurts and a control without yoghurt, there were marked improvements in the red blood cell counts, white blood cell counts but no significant difference in the differentials at p ≤0.05. The isolates were also observed to have no disruptive effect on the morphology and structure of the small intestine. Overall, the use of these lactic acid bacteria strains showed immense benefits in their use as starter cultures and the study demonstrated safety of the final products for consumption.