Survival of free and encapsulated Bifidobacterium lactis (LAFTIB94) and its effect on the sensory and chemical properties of yogurt drink (Doogh)

In this study, survival of Bifidobacterium lactis (LAFTI-B94) was investigated in both free and microencapsulated forms and its effect on physicochemical, sensory and rheological properties of Doogh was screened during 60 days at 5±1°C cold room. Treatments involved C (control, no probiotic), B and BC containing Bifidobacterium lactis in free and microencapsulated form respectively. The analysis of the results showed that the number of Bifidobacterium lactis counts decreased in free form 0.26 log and increased in capsulated form 0.36 log. The results also indicated that both free and microencapsulated form were efficient enough to keep the number of probiotic bacteria above the threshold level for minimum therapeutic 107 CFU g-1 of Doogh but the number of bacteria added in microencapsulated form was higher than that of the free form of bacteria. The analysis of the results showed that amount of moisture, acidity, pH content, stability and viscosity were significantly different between samples of doogh (P <0.01). The probiotics bacterial improved viscosity and stability of Doogh that encapsulated forms showed to have higher stability (46.25%) and viscosity (54.13 cP) than those of free forms. According to the results of sensory evaluations, significant difference was observed between the samples from a flavor point of view. Doogh samples containing Bifidobacterium lactis respectively gained higher scores for flavor in comparison with other samples (P<0.05). So probiotics not only did not adversely affect physicochemical and sensory properties, but also improved the stability and rheological properties and flavor of Doogh; Therefore, Doogh can be an effective medium for delivering probiotic organisms.