optimizing yoghurt-ice cream mix blend in soy based frozen yoghurt

yoghurt ice cream (yic) or frozen yoghurt dessert can be regarded as a healthy alternative to plain ice cream. also use of soy derived products in food formulations can lead to the development of products of improved nutritional and health promoting values. yoghurt ice cream was prepared using full-fat soy flour to substitute 55% of non fat dry milk content. product formulation comprised of 12% snf, 10% fat, 18% sucrose, 0.4% stabilizer-emulsifier and 0.1% vanillin. the effect of incorporating yoghurt at the rate of 5.3%,15.9%, 26.5%, 37.1% and 47.7% of the total ice cream mix on the flow behavior, physico-chemical and sensory properties of yoghurt ice cream was evaluated as compared with control, devoid of any yoghurt. the mixes all showed pseudoplastic flow behavior, with the viscosity increasing from 0.7 to 1.57 pa s when the yoghurt content increased from 0 to 47.7%. higher contents of yoghurt in the mixes significantly improved the melting rate of the yoghurt ice cream where the minimum melting rate (16%) was obtained for the sample of 47.7% yoghurt content. the highest overrun value of 58% was obtained for the sample containing 15.9% yoghurt. however the specific gravity of the product decreased with increasing yoghurt content with the highest specific gravity of 1.108 being recorded for control. in the light of these findings, it can be concluded that yoghurt ice cream, containing full fat soy flour, can be successfully made by incorporating 25.6% yoghurt in the mix with the end product maintaining its acceptable sensory characteristics.