The effect of Basil seed gum as a fat replacer on physico-chemical, micro structural and sensory properties of low-fat set yogurt

Basil seed gum (BSG) was used as a fat replacer in formulation of low-fat set yogurt and its characteristics were studied. Basil seed gum was added to reconstituted skim milk at five levels (0.01, 0.04, 0.07, 0.1 and 0.2%). Considering a blank sample, the mixtures were inoculated using a DVS yogurt starter culture and the obtained yogurt stored at 5°C. Physico-chemical properties of the yogurt samples such as pH, acidity, syneresis, apparent viscosity, hysteresis area, and microstructure, textural and sensory properties were studied after one and seven days storage. During one week storage, the pHs of samples did not show any significant differences. However, acidity of yogurt significantly changed (P<0.05). The textural evaluation of the samples contains 0.1 and 0.2% BSG were significantly different from the others and showed the lowest modulus of elasticity. Apparent viscosity, modulus of elasticity, values of syneresis and hysteresis of yogurt decreased as BSG concentration changed from 0.01 to 0.2%. Scanning electron microscopy (SEM) of yogurt samples contains 0.1 and 0.2% BSG were significantly different from the blank sample and showed smoother microstructure. The analysis of sensory properties indicated that the color, odor and flavor of samples did not show any significant differences. Although, the differences between the samples and the blank in terms of sourness, hardness, consistency in mouth, creaminess, syneresis and total acceptance were highly significant (P<0.01). The results indicated that Basil seed gum at level of 0.2% which has high water holding capacity, good sensory properties and strong interactions with milk proteins is a suitable fat replacer to develop a formulation of low-fat set yogurt.