Effect of different fermentation conditions on texture and rheological properties of fermented bean curd

Effects of processing conditions-Soybean varieties, coagulant, second fermentation temperature and Actinomucor elegans culture duration on fermented bean curd were investigated. Food texture analyzer and rheometer equipments were employed to compare differences of texture and rheology properties in sufu, combining with analysis of moisture content and amino acid nitrogen.The quality of fermented bean curd was found to be greatly affected by the four processing conditions.The gel structure of fermented bean curd made from big soybean variety was more integrity in structure than that from small soybean.Compared with salt coagulant, lactone coagulant significantly reduced hardness of fermented bean curd and improved viscoelasticity. The secondary fermentation temperature of 30℃ significantly improved nitrogen content of amino acids. Incubation duration of mucor also affected rheological property of fermented bean curd, as with 5 days of incubation, nitrogen content of amino acids and viscoelasticity of sufu were greatly decreased.For all samples investigated, G' values was always bigger than G″ values and no intersection appeared on the detection line. This indicated a weak gel structure in sufu.Protein network can be switched to a new structure through further restructuring with the increase of cutting frequency.