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 ºC. 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 lactosefree
milk showed a more yellowish color; however, these differences would not be
detected by the human eye (¿E < 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.
