Comparative physicochemical, antioxidant and sensory evaluation of fruit juices for incorporation into probiotic soy yoghurt

Abstract:

The present study was undertaken to comparatively evaluate selected fruit juices for their suitability in the development of probiotic soy yoghurt. Four fruit juices, namely mango, pineapple, orange and strawberry, were assessed for their physicochemical characteristics, antioxidant properties and influence on the quality attributes of soy yoghurt. The fruit juices were analyzed for pH, total soluble solids (TSS), titratable acidity, total phenolic content (TPC) and DPPH radical scavenging activity. Subsequently, each fruit juice was incorporated into probiotic soy yoghurt at 10% (v/v), and the resulting products were evaluated for physicochemical, rheological, colour and sensory characteristics.

Significant differences (P≤0.05) were observed among the fruit juices with respect to physicochemical and antioxidant properties. Strawberry juice exhibited the highest total phenolic content (119.20 mg GAE/100 g) and DPPH radical scavenging activity (89.20%), followed by orange juice, mango juice and pineapple juice. Incorporation of fruit juices significantly influenced the quality characteristics of soy yoghurt. Strawberry soy yoghurt exhibited the lowest syneresis (9.90%) and highest viscosity (3000 cP), indicating superior gel stability and water-holding capacity. Fruit juice addition also improved colour characteristics and sensory quality compared with the control soy yoghurt. Among the treatments, strawberry soy yoghurt received the highest sensory scores for colour and appearance (8.70), flavour (8.80), body and texture (8.50), taste (8.90) and overall acceptability (8.80) on a nine-point hedonic scale. Mango soy yoghurt ranked second in overall sensory quality, whereas orange and pineapple soy yoghurts showed comparatively lower performance.

An overall performance index integrating antioxidant, rheological and sensory parameters identified strawberry juice as the most suitable fruit juice for probiotic soy yoghurt manufacture. The results demonstrate that incorporation of strawberry juice at 10% level can significantly enhance the functional, technological and sensory quality of probiotic soy yoghurt. Therefore, strawberry juice may be effectively utilized for the development of antioxidant-rich, consumer-acceptable and technologically stable plant-based fermented products.