Combining Strategies for the Development of a Potentially Functional Yogurt: Structural, Physicochemical, and Microbiological Characterization

This work aims to develop and characterize potentially functional yogurts (high-proteins, with bifidobacteria, reduced in lactose and with in situ produced GOS) through combined strategies of ultrafiltration (UF) and the addition of dairy powder ingredient (whey protein concentrate 35% and 80% (WPC35 and WPC80) respectively, and skim milk powder (SMP)). Four yogurt formulations were tested: UF milk (Y1); UF milk and WPC80 (Y2); UF milk and WPC35 (Y3); and skim milk, SMP, and WPC80 (Y4). Carbohydrates, organic acids, particle size distribution, physicochemical, microbiological, rheological, and textural parameters were determined. Y4 presented the highest apparent diameter of casein micelles for both untreated and heat-treated milk, and Y1 presented the lowest values; size particle distributions were different among formulations. The yogurts had high protein content (6.61–7.88 g/100 g) were reduced in lactose (0.55–1.79 g/100 g) and contained GOS (0.33–0.71 g/100 g). All formulations were successful in maintaining Bifidobacteria (Bifidobacterium lactis INL1) and Streptococcus counts at high counts (> 8.5 log CFU/g) during storage. The highest carbohydrate concentrations were for Y3 and Y4 yogurts, reaching the highest GOS concentration. All yogurts exhibited thixotropic behavior. Y4 yogurt showed a slightly different flow behavior than the other samples, exhibiting a higher flow behavior index and higher Kokini viscosity. Y2 and Y4 yogurts presented higher hardness; besides, Y4 presented a clear advantage in water holding capacity. The overall quality of yogurts was satisfactory, showing high potential as functional dairy products.