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The quality of probiotic yogurt which is remarked as a healthy, therapeutic and nutritious food product strongly depends on starter types and their compositions; however, the choice of starter culture affects the taste, aroma and quality of the final product. Through this study, to obtain favorable quality attributes of probiotic yogurt, a mixture of two thermophilic/mesophilic starter cultures (YC- 350/YC- X16) was applied for fermentation.

The effects of starter mixture, probiotic Lactobacillus paracasei and storage time on quality indices, such as apparent viscosity, water holding capacity, syneresis, post acidification rate and probiotic viability (L. paracasei), were assessed through using a combined (mixture-process) statistical design.

The results revealed that changes in viscosity and syneresis depend on the amount of YC- X16. Acidification rate was more pronounced at higher levels of YC- 350 (1.22 per cent) in comparison to that in YC-X16 (1.08 per cent) during storage time. With respect to probiotic viability, L. paracasei count was more than 107 cfu/mL during refrigerated storage time. Moreover, a promotive effect of YC- 350 on L. paracasei proliferation was observed in this study.

The favorable yogurt, from qualitative aspects, was manufactured at 75:25 per cent ratio of YC- X16:YC- 350 in probiotic type yogurts. Therefore, the use of mixed starter cultures developed textural properties of probiotic yogurt beside L. paracasei survival.

The purpose of this paper is to evaluate effects of simultaneous supplementation of milk protein concentrate (MPC) as texture modifier and microencapsulated Lactobacillus paracasei (L. paracasei) (entrapped in gellan–caseinate) on physico-chemical, sensorial and microbial characteristics of yogurt during storage time.

L. paracasei cells were encapsulated through unique pH triggered gelation technique using combination of sodium caseinate-gellan gum as protective shell material. MPC was also used to improve physico-chemical indices of probiotic yogurt at different levels (0–3 percent).

The results showed that yogurt samples containing encapsulated L. paracasei showed lower post-acidification and higher viability. Samples containing encapsulated L. paracasei showed less syneresis amount, due to possible hydration of shell material, also application of MPC could reduce this attribute during storage time. The numbers of probiotic bacteria were remained above the recommended therapeutic minimum throughout the samples.

The findings suggest a practical ingredient in probiotic dairy product. Simultaneous usage of this kind of encapsulation via MPC enhanced sensorial and physical properties of probiotic yogurt while of no reduction in viable counts survival.

This study revealed usage of microcapsules of L. paracasei prepared by the gelation of sodium caseinate-gellan gum could be a suitable manner for delivery of probiotics in fermented dairy products like yogurt.