Influence of red grape pomace powder on physiochemical, antioxidant, nutritional, microbial, and sensory properties of probiotic yoghurt

In this study, we investigated the effect of 2 and 4 % grape pomace powder (GPP) on the physiochemical, nutritional, microbial and sensory properties of probiotic yoghurt (contains Lactobacillus acidophilus and Bifidobacterium bifidum) during the storage period every 7-day intervals (for 28 days). The results revealed that the pH, fat, protein, syneresis and sensory scores of samples decreased with elevation the grape pomace powder (GPP) level and also storage time. Ash, fiber, energy, total flavonoid, antioxidant activity, total phenol and the counting (log cfu/mL) of probiotic microorganisms decreased during storage, but the treatments with higher GPP had higher ash, fiber, energy, total flavonoid, antioxidant activity, total phenol content and probiotic counts. In converse, the acidity and viscosity increased with time storage and increase the GPP level. The probiotic yoghurt supplanted with 4% GPP in 0 day had the highest ash (1.2%), fiber (0.75%), energy (73.8 kcal/g), total flavonoid (4.9 mg Rutin equivalents/g) and antioxidant activity (42.4%). The highest viable count at the end of storage period (28 day) was obtained for probiotic yoghurt containing 4% GPP (8.03 log cfu/mL) and the lowest for control (6.2 log cfu/mL). Also the highest organoleptical scores belonged to yoghurt supplemented with 2% GPP at 0 day. The results of this research showed that grape pomace can be used in the production of probiotic yoghurt.