Impact of hydrocolloids effects on gel structure of milk proteins during the fermentation of yogurt

In current study, the effect of different hydrocolloids as stabilizer (high bloom gelatin (HBG), low bloom gelatin (LBG), cold water fish skin gelatin (FSG), low methoxyl pectin (LMP) and modified tapioca starch (MS)), was investigated on physicochemical and rheological properties of yogurt in four concentrations. The results showed that in all samples, except pectin, PH decreased over time, but pH reduction in the sample containing modified starch (MS), was significantly higher than other samples. The LMP sample and the HBG sample had the lowest and highest water holding capacity (WHC) with 57 and 78.6 percent respectively. At low concentrations, the stabilizers produced loose tissue in yogurt, but at high concentrations all types of gelatin improved the uniformity of yogurt tissue. The highest tissue consistency was observed in the HBG sample. Also, viscosity of the samples increased with the addition of stabilizers, and there was a significant relationship between stabilizers concentration and viscosity. All of types of gelatin decreased number of grains but starch significantly increased graininess in all concentrations (p<0.05). However FSG showed the best effect and decreasing of graininess.