Effect of fermentation on physico-chemical, textural properties and yoghurt bacteria in mango soy fortified yoghurt

Abstract

Mango soy fortified yoghurt (MSFY) samples were prepared by using blends of 78.3% milk containing 3% fat, 14.5% soymilk containing 8.2% total solids and 7.2% mango pulp containing 18% total solids. The physico-chemical, textural properties and yoghurt bacteria counts of MSFY were analyzed at an interval of 30 min during fermentation upto 270 min. The fermentation time had a positive effect on acidity but a negative effect on pH, total solids and sugars in MSFY. Quadratic model were well fitted into different physico-chemical properties of MSFY during fermentation. Textural profile data of MSFY during fermentation were: hardness (46.44-154.6 g), cohesiveness (0.4133-0.8137), adhesiveness (-2.57 to-59.77 g.s), springiness (1.037-1.416) and gumminess (26.22-93.80 g). The Streptococcus thermophilus counts increased from 1.3 × 10 8 to 1.75 × 10 9 cfu/ml and Lactobacillus bulgaricus from 0.9 × 10 8 to 1.17 × 10 9 cfu/ml. Specific growth rate of S. thermophilus is higher than that of L. bulgaricus during MSFY fermentation.