Encapsulated Bifidobacterium BB-12 addition in a concentrated lactose-free yogurt: Its survival during storage and effects on the product's properties. (December 2021) - Dantas, Adriana
Graphical abstract: Highlights: Lactose-free milk and/or prebiotic spray-dried powders showed probiotic stability. Lactose-free milk and/or prebiotic spray-dried powders showed BAL stability. The probiotic survival rate was higher for the yogurt with free cells. Encapsulated probiotic addition with lactose-free milk showed the highest survival rate. Physicochemical behavior was favorable to probiotic skyr-style yogurts elaboration. Abstract: This work aims to manufacture a new concentrated lactose-free probiotic yogurt. For this purpose, the probiotic Bifidocaterium BB-12 was incorporated in a concentrated lactose-free yogurt, both in its free form and previously encapsulated. Previous cell encapsulation was performed using the spray-drying technique with the following wall materials: lactose-free milk, lactose-free milk and inulin, and lactose-free milk and oligofructose. Thus, three different probiotic powders were obtained and added separately to three fractions of concentrated lactose-free yogurt. The probiotic survival of both powders and yogurts was evaluated during refrigerated storage. Likewise, the viability of starter cultures in yogurt ( Lactobacillus bulgaricus and Streptococcus thermophilus ) was controlled. In addition, the physicochemical properties of the four yogurts were also measured (color, pH and acidity, and texture properties). All three powders showed good probiotic viability (>8 log CFU g −1 ) throughout 120 days of storage at 4 °C. In turn, yogurt formulations (with the addition of powders or free bifidobacteria) presented probiotic viability above 7 log CFU g −1 after storage; as well as the starter cultures (>8 log UFC g −1 ). Yogurt with probiotic powder from lactose-free milk showed a more yellowish color; however, these differences would not be detected by the human eye (ΔE < 3.00). The yogurt with bifidobacteria free cells showed a greater post-acidification process (pH 4.18 to 4.02 and titratable acidity 1.52 to 1.89). It was not observed differences for firmness values of yogurt with free cells addition and yogurt with lactose-free milk and oligofructose powder addition. A slight significant decrease in the cohesiveness was observed in the yogurt elaborated with bifidobacteria free cells. The gumminess showed fluctuating values between all concentrated lactose-free yogurts. At the end of this study, we conclude that these probiotic powders can be incorporated into innovative lactose-free yogurts.