Bifidobacterium animalis subsp. lactis BB12-Derived Postbiotic Powders Enhance Antioxidant and Physicochemical Properties of Low-Fat Yoghurt

Fortifying conventional foods with postbiotic powders (PP) is an effective approach for the production of functional products. Preserving both functional properties of PP and the physical characteristics of fortified products is essential during this process. This study aimed to investigate the antioxidant activity and consumer testing of low-fat yoghurt fortified with PP and changes in their physical properties, including rheology, water holding capacity, and microstructure over a 21-day storage period. PP, derived from Bifidobacterium animalis subsp. lactis BB12 grown in cheese whey (CW) and skim milk (SM), was added to the product at 1% individually (B12-CW and B12-SM) and in a mixture (BB12-CW-SM). The results indicated that the antioxidant activity of the samples fortified with PP was 4.6-6.3%, almost double the values in samples without PP, despite their similar viability of starters (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) (>8.5 log cfu/g). Adding BB12-CW significantly reduced mouthfeel, flavor, and overall acceptability of the product, while adding BB12-SM and BB12-CW-SM did not alter any consumer acceptability. Similarly, regardless of PP types, their fortification had negligible effects on viscosity, viscoelastic properties, shear-thinning behaviors, water-holding capacity, and microstructure formation, which remained nearly unchanged during storage. Overall, the addition of PP, particularly BB12-SM and BB12-CW-SM, significantly increased antioxidant activity while preserving important physical and consumer acceptance of yoghurt. These findings underscore the potential of postbiotics as functional ingredients, enhancing both the nutritional values and consumer appeal of yoghurt, thereby promoting its health benefits.