Processing,Quality Improvement And Storage Characteristics Of Frozen Soybean Skins

"Sanxian soybean skins" is one of Wuhan's famous spots.It has a long history and enjoys the reputation of "the king of soybean skins".It is famous for its unique flavor.With the acceleration of modern life pace,people's demand for convenience food has increased substantially,and the industrialization of frozen food has been particularly rapid.However,in this new situation,the modern processing and storage technology of soybean skin is still immature,making its industrial progress has been slow.Considering that soybean skins belong to starchy products,the retrogradation of glutinous rice starch will be involved in the processing and storage process,which will cause deterioration of its quality.It will be hard texture and poor taste,and it will be difficult for digest and absorb in vivo.Therefore,this paper studied the optimization of key process parameters in the processing of frozen soybean skins,and further explored the effects of compound additives on the quality of frozen soybean skins,and the effects of freeze-thaw cycles and frozen-storage time on the storage characteristics of soybean skin.To provide a theoretical basis for promoting the industrialization of frozen bean skin.The main results of this study are as follows:(1)Optimization of key process parameters during processing of f frozen soybean skins:By examining the water absorption of glutinous rice under different soaking conditions,the optimum temperature,pH value and time for soaking glutinous rice were screened.Based on the comprehensive evaluation of frozen soybean skins which performed through TPA texture analyzer,digestion characteristics,DSC,water holding capacity,and sensory characteristics,we select the best pre-cooling temperature.In addition,TPA texture analyzer and sensory properties were used to evaluate the quality of frozen soybean skins after re-heating,and the best re-heating method was selected.Results show that the water content of glutinous rice is closely related to the temperature,pH value and time for soak.The optimal soaking temperature,pH value and time are 35 °C,8.5 and 3 h,respectively.The physiochemical properties of the frozen soybean skins are different between different pre-cooling treatment.Compared with the pre-cooling temperature at 0 °C and-40 °C,there is significant differences among the two methods.The latter is closer to the fresh products.When pre-cooling treatment for frozen soybean skins at-40 °C can effectively delay the retrogradation of starch,the storage stability of frozen soybean skins is better,more conducive to maintaining its quality.Moreover,compared to other reheating methods such as microwave and packaged boiled,the frozen soybean skins has the best quality after re-steaming.It has the smallest hardness value and the sensory characteristics are closer to that of fresh soybean skins.That is,the method of re-steaming is more conducive to the preservation of the quality of the frozen bean skin after re-heating.(2)Improvement of the quality of frozen hides and skins with compound additives:By examining the fast-digesting starch content of glutinous rice in frozen soybean skins,the quality improvement agent's compounding scheme was determined;and the quality differences of the frozen and preserved soybean skins were evaluated by combining the TPA full texture,water holding capacity,LF-NMR,and sensory characteristics.The experimental results show that different additives(monoglycerides,trehalose and sucrose esters)can effectively increase the fast-digesting starch content of glutinous rice in frozen soybean skin within a certain range of added amounts,and a single factor response surface analysis is used.The optimal addition amounts of monoglyceride,trehalose,and sucrose ester were 1%,2.5%,and 2%,respectively.At this time,the content of fast-digestible starch was higher,and the quality of frozen hideskin was the best,which was close to the prediction model.In addition,experiments have shown that compounding additives can significantly inhibit the aging of glutinous rice starch gel in soybean skins.(3)Effects of freeze-thaw cycle and frozen storage time on storage characteristics of soybean skins:The effect of temperature fluctuation on the digestive characteristics of indica rice in frozen soybean skins was investigated by TPA full texture and digestion characteristics,and the peroxide value,volatile base nitrogen(TVB-N),and microbiological indicators of frozen soybean skins.To clarify the effect of frozen storage time on the storage characteristics of frozen soybean skins.The experimental results showed that repeated freeze-thaw cycles resulted in the quality deterioration of the soybean skins,which showed an increase in the hardness of the starch gel and decreased water holding capacity.The compounding additive can effectively improve the quality of the soybean skins,making it more suitable for long-term storage.In addition,with the extension of frozen storage time,the oxidation degree of oil in the skins of different processing methods(natural thawing without additives,natural thawing with additives,reheating without additives,and reheating with additives)has increased.However,the peroxide value did not exceed the national standard within 90 days of frozen storage.With the prolonged storage time,volatile nitrogen content in lean muscle of all four kinds of soybean skins increased.At the same frozen time,there was no significant difference in volatile nitrogen content(p>0.05).After 75 days,the lean meat in the four kinds of soybean skins is no longer suitable for eating.In addition,with the extension of storage time,the total number of colonies of non-reheated bean skin accessories grew rapidly,exceeding the national standard after 30 days of frozen storage.The total number of colonies of the frozen soybean skins after re-heating was not detected.Based on the effect of freeze-thaw cycle and frozen storage time on the quality of frozen soybean skins,it provides a practical reference for its frozen storage.