Berry pulp incorporation into probiotic yoghurt: Microbiological, textural and sensory properties, and antioxidant activity

The effect of different berry fruits on the bacterial survival, antioxidant, textural, and sensory characteristics of probiotic yoghurt containing Lactobacillus acidophilus LA-5, and Bifidobacterium animalis subsp. lactis BB-12® was investigated during 21 days of storage. In this context, raspberry (Rubus idaeus), goji berry (Lycium barbarum), or blueberry (Vaccinium corymbosum) pulp (15 %) containing fruit and sugar in a 1:1 ratio was used in the yoghurt manufacture. Yoghurt without any fruit pulp was the control sample. The viable cell counts of yoghurt starter bacteria and probiotic bacteria were above 7.50 and 8.70 log CFU/g, respectively, meeting the recommended minimum levels. The highest viability of L. acidophilus was in goji berry-added yoghurt for 14 days of storage. In contrast, the superiority of goji berries for the viable count of B. lactis could be determined only on the 14th and 21st days. Goji berry-supplemented probiotic yoghurt showed the highest total phenolic content and (2,2-diphenyl-1-picrylhydrazyl) radical (DPPH˙) scavenging activity throughout the storage. Yoghurt containing blueberry pulp had a higher anthocyanin amount than the sample with raspberry during storage. In contrast, anthocyanin, in terms of the pelargonidin-3-glycoside, could not be determined in probiotic yoghurt with goji berry pulp. The supplementation of probiotic yoghurt with berry pulp improved the viscosity and water-holding capacity properties; however, it had generally no significant effect on the sensory characteristics.