Quality Assessment of Tofu from Black Soybean (Glycine max.) by using Natural and Synthetic Coagulant

Abstract

The quality assessment of different types tofu (normal, silken and intermediate dried) prepared from black soybean (Glycine max) using lime juice and calcium chloride in terms of yield, proximate composition, sensory analysis and functional properties. Curds were prepared using 2.5% of calcium chloride and 2.5% lime juice respectively based on soymilk (acidity as 6.88% citric acid). The lime juice produced significantly (p<0.05) higher yield percentage compared to calcium chloride on dry basis respectively. The proximate analysis revealed that the protein content, fat, ash and carbohydrate differed significantly (p<0.05). The lemon juice coagulated tofu had the highest protein content but lowest carbohydrate content in intermediate dried tofu on dry basis. The phytic acid content was found to be decrease in all types of tofu, whereas oxalate content increased in all tofu prepared using lemon juice. Silken tofu coagulated by calcium content showed higher total phenolic content compared to that of other tofu samples. Similarly, silken tofu coagulated with calcium chloride showed higher radical scavenging activity compared to other types of tofu coagulated by lemon juice and calcium chloride. From the sensory evaluation, normal tofu coagulated by lemon juice was better preferred compared to that of other different types of tofu.