Functional and technological attributes of probiotic yoghurt prepared with Dahi micro-flora during refrigerated storage

Evaluation of Spreadable Kefir Produced from Different Milks in Terms of Some Quality Criteria

Kefir, which has many beneficial effects on health, is one of the most consumed fermented milk products worldwide. It is important to increase consumption of the fermented product for public health. In this study, it was aimed to increase the beneficial effects of kefir on public health. Therefore, kefirs produced from different types of milk (cow, buffalo, sheep, and goat) were concentrated, and obtained spreadable kefir samples were investigated in terms of their microbiological characteristic (lactic bacilli, lactic cocci, yeasts and moulds, total bacteria, and coliform bacteria), benzoic acid content, physicochemical properties (fat, total solid, ash content, acidity, pH, syneresis, viscosity, colour, and rheological properties), and sensory characteristic. It was determined that APC, lactic bacilli, lactic cocci, and yeast counts of the concentrated kefir samples changed between 6.90 and 8.64, 6.89 and 8.61, 7.42 and 8.72, and 2.17 and 5.39 log CFU/g, respectively, during storage. Mould and coliform bacteria were not detected in the samples. The concentrated kefir samples contained benzoic acid in the range of 18.30-119.58 mg/L. Results from this study showed that type of milk caused differences on APC, lactic bacilli, lactic cocci and yeast count, total solids, ash, fat, acidity, pH, syneresis, colour, viscosity and rheological parameters, and benzoic acid content. In addition, milk type affected sensory properties of the kefirs. Concentrated kefirs produced from cow and buffalo milk were the most liked by panellists. Finally, it was determined that concentrated kefir was favoured as a new product by most of the panellists.

Effects of Lactobacillus fermentum HY01 on the quality characteristics and storage stability of yak yogurt

Lactobacillus fermentum HY01 is a probiotic strain screened from traditional yak yogurt, which can effectively relieve enteritis and constipation. This study aimed to evaluate the effects of HY01 as an adjunct starter on the quality and storage of yak yogurt. A total of 36 main volatile flavor substances were detected in all samples. In particular, more aldehydes, esters, and alcohols were detected in yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 (including Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). The rheological results showed that the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter MY105 had higher apparent viscosity and lower tan δ value compared with compared with traditional yak yogurt, yak yogurt with only L. fermentum HY01, and cow yogurt with L. fermentum HY01 and starter MY105. Meanwhile, the conjugated linoleic acid in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was significantly higher than those in the HY01 group or the yogurt starter group alone. After 28 d of storage at 4°C, the number of HY01 in the yak yogurt prepared by mixed fermentation of L. fermentum HY01 and starter was still higher than 10⁷ cfu/mL, its acidity was lower than 110°T, and its syneresis was the lowest. The results indicated that L. fermentum HY01 could improve the flavor, texture, and storage properties of yak yogurt.