Effects Of Pre-treatment Methods On Tofu's Texture And In Vitro Gastric Digestion Characterastics

Tofu is a traditional product made from soybeans,which has a smooth taste and rich nutrition.Usually,tofu needs to be boiled,microwaved and fried before being eaten.Protein in tofu is consumed after undergoing various degrees of pre-treatment.Changes in protein structure and assembly as a result of processing impact the digestibility of proteins.In this paper,tofu was used as the experimental object to study the effects of different pre-treatment methods on tofu's components,gel structure,texture characteristics,chewing characteristics and in vitro gastric digestion characteristics,and discusses the relationship between tofu's structure and the digestibility of tofu protein.1.The effects of three different pre-treatment methods on tofu components,gel structure and texture properties were studied.The results show that after the tofu was processed by different pre-processing methods,the protein aggregates and the uniform honeycomb network gel structure becomes loose,irregular and locally dense.The moisture content of tofu is reduced,the protein content is increased,and the resilence and springiness are reduced.Boiled tofu has higher hardness and chewiness,microwave-treated tofu has higher cohesion,and fried tofu has lower hardness,recovery,cohesion,elasticity and chewiness.2.The effects of three different pre-treatment methods on the chewing characteristics of tofu simulation were studied.Using an in vitro simulated chewing experiment,a double exponential decay function fitting analysis was performed on the energy consumption changes during tofu chewing.The results showed that the chewing energy consumption of tofu decreased significantly with the increase in the number of chewings.The total energy consumption of chewing fried tofu was significantly higher than that of other groups,followed by boiled tofu,and the total energy consumption of microwave heated tofu was lower.The energy consumption of mastication consists of the energy consumption required to destroy the gel structure of the tofu and the functional consumption of overcoming the cohesiveness of the broken particles.The former has a greater contribution rate.3.The protein digestion characteristics of tofu in the in vitro gastric digestion process under three different pre-treatment conditions were studied.The results showed that with the increase of digestion time,the recovery rate of tofu protein in each group gradually increased,and the digestion rate first decreased significantly and then gradually became flat.The protein content in solution,protein recovery rate and average digestion rate of the tofu fried for 1 min were the highest.Tofu boiled for 15 minutes is relatively low.As the digestion time increases,the turbidity of the enzymatic hydrolysate decreases,the absolute value of the Zeta potential gradually increases,the conductivity gradually decreases,and the particle size gradually decreases.Tofu protein is continuously decomposed by pepsin,so that peptides with a molecular weight of 1?50 kDa gradually increase.The tofu enzymatic hydrolysate showed a certain viscosity at low shear rate,and the viscosity increased when fried tofu was digested for2 h and 3 h.Boiled tofu has the lowest viscosity and the smallest proportion of small peptides.