Microbiological, antioxidant, and sensory properties of probiotic yoghurt enriched with different strawberry varieties

Abstract

The influence of different strawberry varieties on the microbiological, antioxidant and sensory properties of probiotic yoghurt, containing Bifidobacterium animalis subsp. lactis Bb12, were monitored for 21 days. For this purpose, strawberry pulp (15 %) containing strawberry and sugar in a 1:1 ratio was used in the yoghurt formulation. Higher total phenolic content and ferric reducing antioxidant power (FRAP) were detected in Albion and Camarosa varieties than Rubygem whereas Albion variety had the highest total anthocyanin content (p<0.05). Colour parameters (L*, a*, b*) of probiotic yoghurts differed significantly with the incorporation of strawberry pulp. The viable counts of yoghurt starter bacteria in the experimental yoghurts remained above 7.64 log cfu/g throughout the storage period. Addition of probiotic yoghurt with strawberry pulp enhanced the viability of S. thermophilus and L. bulgaricus depending on the variety of strawberry. A similar effect on B. lactis viability was observed in fruit probiotic yoghurt samples except the 1st day of storage. The counts of B. lactis were above 8.5 log cfu/g throughout the storage period. The highest total phenolic content, antioxidant activity (FRAP) and total anthocyanin content were found in Albion variety added probiotic yoghurt during the storage period. Sensory characteristics of probiotic yoghurt were not generally influenced by the addition of strawberry while sample enriched with Camarosa variety showed the lowest overall acceptability scores on 14th day.

Keywords

• strawberry
• yoghurt
• probiotic bacteria
• viability
• antioxidant activity