Physico-chemical, antioxidant and sensory properties of stirred yoghurt containing Ber (Zizyphus mauritiana) fruit extract

Abstract

: In this study polyphenol extract (BPE) of Ber fruit ( Zizyphus mauritiana ) was prepared by vacuum evaporation of ethanol extract of edible portion (pulp and skin) of fruit fortified into stirred yoghurt. A ratio of 0.20 BPE (mg/g) to 1.0 BPE (mg/g) was added for yoghurt preparation. Based on various sensory attributes, stirred yoghurt with BPE 0.8 mg /g per cent was chosen as best among these samples when compared with the control stirred yoghurt. Optimized yoghurt contains 82.36±0.545 % moisture, 6.45±0.08 % protein, 0.98±0.001 % ash, 0.1% fat, 0.026 ppm Mn, 3.85 ppm Zn, 0.9407 ppm Cu and 950 ppm Ca, respectively. Water holding capacity of the fortified yoghurt increased significantly on increasing the BPE concentration from 41.23±0.73g/100g to 46.66 ± 1.13g/100g. Total phenolic content increased significantly on increasing the concentration of BPE 0.8 mg/g. Fortification of BPE resulted in Total Phenolic Content (TPC) of 504.4± 9.3μg GAE/ g from 216.88±9.41μg GAE/ g in control sample. Storage period of 20 days showed non-significant losses in total phenolic content and antioxidant capacity. TPC decreased from 504.4±9.3 μg GAE/g to 438.17±15.58 μg GAE/g and % DPPH inhibition decreased from 74.22 ±2.77% to 67.4 ±1.32% after 20 days storage at 4°C.