| As one of the deep-fried food,the Fried meat has the characteristics of crisp outside and tender inside,and is deeply loved by consumers everywhere.However,it is easy to lose water in the process of curing,frying and so on,which makes the meat hard and the food quality worse,which greatly limits the further production of frying products.In order to improve the tenderness quality of paste meat,this study optimized the product process and analyzed the mechanism of tenderness change.Taking the pork tenderloin as raw material,this study systematically studied the changes of tenderness and quality of pork slices during tenderizing,curing,hanging paste and frying by means of single-factor test,orthogonal test,response surface test,dynamics and other methods.The dynamic changes of mass transfer during pickling were investigated.The relationship between the temperature of frying center and the tenderness of meat was analyzed.The research results can provide theoretical support for the standardized cooking operation of Fried meat slices with hanging paste and fill the gap in the research of tenderizing Fried pork slices with paste.The main results are as follows:1.Papain and ultrasonic were used to tenderize pork tenderloin,and the water retention,shear force,tissue protein content and myofibrillar microstructure of tenderloin were used as evaluation indexes to determine the optimal technological conditions.The results showed that:（1）papain and ultrasonic treatment could improve the tenderizing quality of pork tenderloin（P<0.05）.（2）The optimum conditions for the action of papain were:Amount of papain add is 6 U/mL,tenderizing temperature is40℃,tenderizing time is 45 min,pH is 7.0.Under these conditions,the shear force of pork slices was8.84 N,and the cooking loss rate was 29.42%.The significant degree of influence of various process parameters on the test results was as follows:tenderizing time>papain concentration>tenderizing temperature>pH.（3）The optimum technological conditions for ultrasonic tenderizing were 160 W-25min,under which the shear force of pork tenderloin was 11.78 N and the cooking loss rate was 35.40%.（4）The tenderizing effect of papain was significantly better than that of ultrasonic（P<0.05）,which could reduce the shear force and cooking loss rate of the meat to 41.10%and 53.98%of the raw meat.2.A kinetic model was established to explore the mass transfer and the quality change of tenderness of different salt fractions（1-5%）and curing time（0-5h）.The results showed that:（1）with the extension of salt content and the increase of curing time,the moisture content,NaCl content and total mass of meat slices increased gradually,and the trend of increase has declined somewhat.In addition,the change rate of water content and NaCl content had a good correlation with the change rate of meat quality（R2=0.974）.（2）When the mass fraction of salt was 3%,the maximum salting diffusion coefficient（De）was4.230×10-10 m2/s,the electrophoretograms of actin（45 kDa）and myosin light chains（25 kDa,15 kDa）were the most obvious,and the meat was the most tender.The contents of essential amino acids and total free amino acids in meat slices were decreased with the increase of salt mass fraction and curing time.Combining physicochemical,nutritional and cost factors,the curing time of 3%salt within 2 h was appropriate.3.Optimization of the paste processing formula by single factor in combination with response surface method,To explore the effects of starch type,starch amount,water amount and baking powder amount on the color of paste shell.The results were as follows:（1）the content of amylose in potato starch,pea starch and corn starch was higher,and the film-forming ability was better.（2）The optimal paste preparation process was as follows:potato starch added amount was 75 g,water added amount was 99 g,and baking powder added amount was 1.20%.At this time,the minimum shear force was 9.44N.The order of the influence of each technological parameter on the test results was as follows:water added amount>potato starch added amount>baking powder added amount.4.The change of shear force and cooking loss rate of meat slices were studied at different frying temperatures（160200℃）to different central temperatures（60100℃）.The mechanism of tenderness change was analyzed and the technological conditions of twice frying were optimized.The results showed that:（1）with the increase of central temperature,the shear force of meat increased in stages.The first stage is 6080℃,in which the shear force increases significantly（P<0.01）.In the second stage,the shear force increases slowly in the range of 80100℃（P<0.05）.（2）Based on the content of MFI,CSP,free actin and amino acids,it was believed that the increase of shear force in the first stage was mainly due to the combination of actin and myosin into an irreversible actin molecule.In the second stage,the change of shear force was mainly caused by the dissolution of collagen,which made the increase of shear force insignificant.（3）The shear force of meat samples was positively correlated with cooking loss rate（P<0.05）,and negatively correlated with MFI,CSP and actomosin（P<0.05）.Cooking loss rate was negatively correlated with actin（P<0.05）.MFI was positively correlated with CSP（P<0.01）.（4）The optimal technological conditions for two deep-frying are:the initial frying temperature and time is 180℃-110 s,and the refrying time is 200℃-40 s. |
