Study On Factors Influencing The Formation Process Of Fermented Bean Curd Texture

As a traditional Chinese fermented food,sufu has a unique flavor,soft texture,rich nutrition,and contains a variety of essential human amino acids.At present,most of the research on the quality of sufu is mainly based on sensory evaluation,which is affected by subjective factors,and there are differences in quality judgments,and it is impossible to achieve numerical quality indicators of sufu.The texture characteristics of sufu can directly reflect the quality of sufu.In order to quantify the quality index of sufu and improve the quality of sufu production,this study uses Guizhou flavored sufu as the test material.The effects of 9 single factors,namely,blooming temperature,blooming humidity,blooming time,pickling time,inoculation amount,and fermentation temperature,on the texture characteristics of green body and amino acid nitrogen content,combined with sensory evaluation and statistical analysis of the texture characteristics of sufu At the same time,using partial correlation analysis to screen out the 4factors that have the greatest impact on the amino acid nitrogen content,namely,the amount of inoculation,blooming temperature,blooming humidity,and blooming time.Orthogonal experiments were performed to optimize the sufu Production process parameters.In addition,explore the changes in fermented sufu body texture profile analysis(TPA),protease activity,and microstructure.The main results obtained are as follows:1.The texture profile analysis(TPA)of fermented sufu by texture analyzer showed that the hardness,viscosity and chewiness of sufu body first increased and then decreased during the whole fermentation process.Reach the maximum value;the adhesion is directly proportional to the fermentation time;the overall elasticity shows a downward trend,with a short increase in the middle;the cohesion is inversely proportional to the fermentation time.The postfermentation stage of sufu is the period where the texture characteristics change the most,but the most significant contribution to the texture characteristics of sufu is the pre-fermentation period of sufu.Controlling the process parameters of the pre-fermentation can control the formation of the texture of sufu.Through the detection of the texture of sufu,it can directly reflect the change process of the structure of the fermented sufu in each stage;2.Observing the sufu structure at different fermentation stages by scanning electron microscope,it is found that the white blank body has a dense network structure;the blank body becomes loose due to the microbial fermentation structure;the salt blank has an increase in water loss and hardness,and the structure shows a dense network structure;The surface of the green body becomes loose after 1 week of fermentation,and the inside remains compact;the whole body of the second fermentation is a loose network structure;the network structure of the green body after 3 weeks is damaged,and macromolecular substances and loose spaces can be clearly observed;After 4 weeks of fermentation,the macromolecular material of the body is decomposed into small molecules,the space becomes looser,the network structure basically disappears,and a sponge-like structure is formed;after 2 months of fermentation,the macromolecular material of the body is basically decomposed into small molecules;mature The sufu body has strong protease activity,high amino acid nitrogen content,and its microstructure is in a delicate and smooth state.The change process of the microstructure is related to the change process of the texture characteristics.When the microstructure changes from a dense structure to a loose structure,its elasticity,hardness and chewiness gradually decrease,and the cohesion,adhesiveness and hardness change trends are the same.3.The protease activity of sufu at different stages of fermentation was tested,and the results showed that the protease activity can intuitively reflect the rate and degree of protein decomposition.The enzyme activities of acidic,neutral,and alkaline proteases all showed the phenomenon of first increasing,then decreasing,then increasing and decreasing,and the enzyme activity was the highest in the rough stage.After the white billet is fermented by microorganisms,the protease enzyme activity increases rapidly.After the salt billet is pickled with salt water,the microbial reproduction is inhibited,and the protease enzyme activity decreases.After 2 weeks of post-fermentation,the number of microorganisms increases,and the protease enzyme activity increases;After 4 weeks of post-fermentation,the oxygen in the mature fermentation bottle is gradually exhausted,and the microorganisms die or dormant,causing the protease activity to drop to a stable level again.Before 3 months of postfermentation,the enzyme activities of the three types of proteases were: alkaline protease>neutral protease>acid protease;after three months of post-fermentation,the enzyme activities of the three types of proteases were: acid protease>neutral protease>alkaline.Protease.Protease enzyme activity can directly affect the decomposition process of sufu body protein,and the decomposition of protein is the main reason for the changes in the texture characteristics of sufu.4.The important influencing factors for the formation of sufu texture characteristics are the moisture content of the white slab,the salt content of the salt slab,the spacing of the white slab,the amount of inoculation,the blooming temperature,the sprouting humidity,and the blooming time.The salt content of the salt billet directly affects the qualified rate of fermented bean curd products.The order of pre-fermentation process on the texture formation of fermented bean curd is blooming humidity> blooming time> blooming temperature> spore inoculation amount.The texture characteristics of mature high-quality fermented bean curd are hardness of 17.5 N,adhesion of 1.4 N.mm,and elasticity of 2.4 mm.,Cohesiveness 0.4 Ratio,adhesiveness 6.3 N,chewiness 30.3 mj.The production process parameters of stable and high-quality fermented bean curd are: the moisture content of the white slab is 66%-68%;the salt content of the salt slab is 8%;the slab is marinated for 15 hours;the white slab spacing is 2.0 cm;the number of spores in a single field of view under a 400 x optical microscope is 5;Flowering temperature is28?;Flowering humidity is 90%;Flowering time is 40 h;Fermentation temperature is 28?.