Incorporation of Encapsulated Yoghurt Bacteria into Stirred Yoghurt to Improve their Survival in an In Vitro Digestive Conditions

In this study, Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus as yoghurt bacteria were encapsulated by electrospraying using mixture solutions of whey protein isolate and inulin. The yoghurt capsules with the highest encapsulation efficiency and tolerance to low pH were used in stirred yoghurt manufacture. The viability of yoghurt bacteria in the stirred yoghurts with and without yoghurt bacteria capsules during 30-day storage and following passage through an in vitro digestive model, and physicochemical properties of the stirred yoghurts during the storage were assessed. Yoghurt bacteria were not found in the yoghurt without the capsules after its passage through the digestive model, while viable counts were above 6 log cfu/g for S. thermophilus and L. delbrueckii subsp. bulgaricus in the yoghurts with the capsules after their passage through the digestive model, regardless of the storage period of the yoghurts. No significant difference was found in syneresis among the yoghurts, but hardness and apparent viscosity of the yoghurts with the capsules were lower than that without the capsules.