Study On Quality Deterioration And Control Ways Of Pre-conditioning Pork Meat Batters During Frozen Storage

In recent years,the deep processing of meat products in China has developed rapidly,meat batters are loved by consumers because of their nutritional balance,ease of consumption,and favored by the meat industry because of high added value and good market prospects.In order to facilitate transportation,sales and long-term storage,the industry generally uses the freezing method to deal with meat products.However,in the process of freezing and freeze-thawing,meat batters will suffer from sensory deterioration such as color browning and taste deterioration.Therefore,understanding the main causes of sensory quality degradation of meat batters and improving the quality of meat batters during freeze storage is an urgent problem for the industry.So,this paper explored the main factors of quality deterioration of meat batters during frozen storage,and studied corresponding improvement measures.The specific content is as follows:First of all,the long-frozen storage will bring many uncertain factors,we determined the typical indexes,water migration,protein denaturation and fat oxidation under different frozen time(0 d?180 d)and freeze-thaw cycles(0 times?7 times)of meat batters and raw meat,thawing loss and cooking loss,protein carbonyl,TBARS and color.Applying multiple linear regression analysis to fit above data,establishing the relationship between the freeze-thaw cycles and frozen time.There was a significant positive correlation between freeze-thaw cycles and frozen time,among which,meat batters Z=-16.2164125+32.4719765×Y-0.7034696×Y~2(R~2=0.9779151),raw meat Z=-12.330767+43.165564×Y-2.363409×Y~2(R~2=0.9556213).Z:frozen storage time,Y:freeze-thaw cycles,freeze-thaw cycles can be used as an accelerated experiment for frozen meat batters and raw meat.Then,using the freeze-thaw cycles of meat batters as an acceleration method,the reasons and main factors of quality deterioration during the frozen storage of meat batters were studied in detail.The cooking loss,water holding capacity,water distribution state,myofibrillar molecular weight,structural change,functional properties,emulsion and rheological properties,fat oxidation,Maillard reaction and color deterioration degree,the tissue structure analysis and sensory analysis were carried out.The results showed that with the increase of frozen storage,the cooking loss of meat batters increased 30.28%(p<0.05),and the water holding capacity decreased.Low-field nuclear magnetic resonance analysis showed that about 98%moisture peak time was 10?100ms,and proportion was gradually decreasing.The content of salt-soluble protein decreased(p<0.05),and the oxidation and structure of protein changed.carbonyl values increased by 45.14%,decreased sulfhydryl content,increased disulfide bonds,and decreased denaturation enthalpy.SDS-PAGE results showed that the protein produced large aggregates and the content of myosin heavy chain(MHC)decreased.Macroscopically,the emulsification performance of myofibrillar protein decreased significantly(p<0.05).The fat was gradually oxidized,TBARS value increased 1.18 mg/kg,free radical content increased,polyunsaturated fatty acids decreased.The Maillard reaction continued,and the Norharman and the CML increased 20.33%and 16.67%respectively(p<0.05).The color of meat batters was deteriorating,which was manifested by a significant decrease in myoglobin content(p<0.05).The ratio of oxygenated myoglobin first increased and then decreased.The ratio of methemoglobin increased,and the red-green value(a~*)decreased.The results of texture and sensory analysis showed that the hardness,elasticity and cohesion of the meat batters decreased,the comprehensive index chewiness decreased by 21.01%(p<0.05),and the sensory evaluation score decreased.Based on deterioration parameters above,PCA was used to study the relevant factors that lead to deterioration,and reasonable parameters were selected to establish a prediction model for the shelf life of meat batters to obtain the best eating time and final shelf life for meat batters.PCA showed that the quality of meat batters deteriorated significantly after 3 freeze-thaw cycles(p<0.05).Pearson correlation analysis showed that the texture and sensory had a strong correlation with protein denaturation indexes(carbonyl,sulfhydryl,disulfide bond,p<0.05),indicating that protein denaturation during freezing and thawing is the main factor that weakens the gel network structure,browning of color,deterioration of texture and decline in sensory scores.According to the results of the correlation analysis,the sulfhydryl and TBARS were selected as the key factors of the shelf life reaction kinetics model,and the shelf life prediction model was established.The comprehensive indicators and the shelf life model showed that the meat batters lost its best taste after 3 freeze-thaw cycles,and it was not suitable to eat after 11cycles.The difference between the predicted value and the actual value was less than 10%,and the model was more accurate.Combining the relationship of frozen storage time and the number of freeze-thaw cycles,it was concluded that the taste deteriorated severely after 75 days of frozen storage.In response of the quality deterioration of meat batters during frozen storage,3%SSPS,1%pig skin gelatin,1%pig skin gelatin hydrolysate and commercial antifreeze(4%sucrose+4%sorbose)were added respectively.To explore their effects on the water holding capacity,color,protein denaturation and sensory quality of frozen meat batters.The results showed that1%gelatin and 1%gelatin hydrolysate significantly improved the water holding capacity of meat batters(p<0.05).The color results showed that the antifreeze had no significant effect on the color of the meat batters.DSC results showed that compared with the blank group(enthalpy change decreased by 21.15%),3%SSPS,1%gelatin and 1%gelatin hydrolysate all effectively slowed down the degree of protein denaturation(enthalpy change decreased by 11.76%,14.58%and 11.53%,respectively),was equivalent to that of commercial antifreeze(12.24%).The rheological and texture results showed that 1%gelatin effectively protected the texture of meat batters and slowed down the decrease in hardness and elasticity,similar to the sensory score results.In summary,the meat batters will produce a series of quality deterioration during the frozen storage,among which protein denaturation is dominant.After 75 days of frozen storage,the taste of the meat batters deteriorates seriously.Gelatin can be used as an effective substitute for commercial antifreeze and added to frozen meat batters as a texture protectant,which can effectively slow down the deterioration of frozen meat batters.