Relevant Research Between Soybean And Tofu Quality And Exploitation Of Acid Coagulant For Tofu

In this paper, taking25soybean varieties from Henan Province as theresearch objects，the contents of soybean composition and quality indexes of north tofuwere determined respectively, relationships between soybean composition and northtofu quality indexes were established by correlation analysis and regression equationswere established by stepwise regression analysis. Fourteen indexes of north tofu wereanalyzed by principal component analysis （PCA） in order to calculate thecomprehensive score, examining soybean varieties which were suitable to north tofumanufacturing. In addition, taking lactic acid, acetic acid, butanedioic acid, tartaric acidand ascorbic acid as the research objects, the effect of addition of single and compoundacid coagulants on the tofu quality was studied in this paper through single-factor andcompositional formulation tests.Main results as follows：1.There were significant differences between protein、water-soluble protein、fat、phytic acid、7S protein and11S protein of different soybean varieties.2.Wet yield of tofu was rather significantly positively correlated to the contents ofprotein、 water-soluble protein、 phytic acid、11S protein of soybean, and wassignificantly negatively correlated to the content of fat; dry yield of tofu was rathersignificantly positively correlated to the contents of protein、water-soluble protein、11Sprotein，was significantly positively correlated to11S/7S, and significantly negativelycorrelated to the content of fat; water-holding capacity of tofu was rather significantlypositively correlated to the contents of protein、water-soluble protein、11S protein insoybean, and significantly positively correlated to the content of phytic acid、11S/7S；hardness of tofu was rather significantly negatively correlated to the content ofwater-soluble protein、phytic acid，and significantly negatively correlated to the contentof11S protein；springiness of tofu was significantly negatively correlated to the contentof phytic acid；cohesiveness、chewiness and resilience of tofu was significantlynegatively correlated to the content of fat； protein content of tofu was rathersignificantly positively correlated to the content of protein，and significantly positivelycorrelated to the content of water-soluble protein；fat content of tofu was rathersignificantly positively correlated to the content of fat； L*value of tofu was significantly negatively correlated to the content of11S protein.3.F value and correlation coefficient R of regression equations obtained bystepwise regression analysis were significant. In this study, mainly impacted wet yieldand hardness of north tofu was mainly impacted by the contents of water-solubleprotein and phytic acid, water-holding capacity and content of protein in north tofu wasmainly impacted by the content of water-soluble protein in soybean，cohesiveness,chewiness and resilience of tofu was mainly impacted by the content of fat.4.Hardness obtained by sense was rather significantly positively correlated tohardness，significantly positively correlated to elasticity and chewiness determined byequipment（r=0.584，0.430，0.433）; taste obtained by sense and cohesiveness、chewinessand resilience determined by equipment showed a significant or rather significantnegelative correlation （r=-0.498,-0.467,-0.516）.Color obtained by sense and yellownessdetermined by equipment showed a rather significant positive correlation （r=0.544）.Sensory overall acceptability obtained by sense was significantly negelativelycorrelated to hardness、cohesiveness、chewness and resilience determined by equipment（r=-0.177,-0.316,-0.238,-0.322）.5.Fourteen quality indexes of the north tofu was processed by principal componentextracting five principal components which can explain84.739%of the overall qualityof the north tofu, and contribution rate of which was36.839%、21.063%、10.808%、9.027%and7.003%, respectively, because of this, five principal components obtainedcould substitute the original fourteen tofu indicators. Quality of twenty-five kinds oftofu was due to contents of wet yield、dry yield、water-holding capacity and hardness.6.Principal component score model（Y=0.435Y1+0.249Y2+0.128Y3+0.107Y4+0.083Y5） was established by principal component analysis, which was used to givedifferent overall score, by which to filter out the most suitable soybean varietyprocessing north tofu, which was Zhong dou24（82-24）. In addition, the experimentproved that examining soybean varieties by principal component analysis was feasible.7.Different kinds and addition of acid coagulant affected tofu quality. The bestadditions of lactic acid, acetic acid, butanedioic acid and tartaric acid as singlecoagulant were1.0%、1.4%、0.6%、0.6%of dry soybean’s weight；the quality of the tofumade with lactic acid was superior to other acids, its sensory score、yield and waterholding capacity was84point、179.55g·100g-1and72.58%, respectively.8.Sense、yield and water-holding capality of tofu made with compound coagulantwere superior to tofu made single coagulant.When the ratio of five acids was0.40% lactic acid、0.26%acetic acid、0.12%butanedioic acid、0.10%tartaric acid and0.02%ascorbic acid, sensory score、yield and water holding capacity of tofu was91point、212.22g·100g^-1and72.33%, respectively. The tofu made with the compound coagulantwas superior to the tofu made with single coagulant.