Study On The Effect Of Sterilization,Cold Storage And Microwave Reheating On The Quality Of Stewed Beef

With the improved living standard and the faster pace of life,safer,more convenient and more nutritious food are preferred.The industrial cooked meat products will be more and more popular.Stewed beef,one of the most popular cooked meat products among people,was chosen as raw material to study the effects of tenderization pretreatment of beef,the low temperature sterilization methods of stewed beef,the stability of cold storage and microwave reheating conditions of stewed beef.This study may provide basis for developing stewed beef products with good quality and storage stability.Firstly,enzyme dosage,treatment temperature and ultrasonic power were chosen as the factors and lean's shear force as the response variable.The tenderization conditions on the beef were optimized by response surface methodology.The results showed that the response surface model was significant(p<0.01)and the optimal conditions were obtained.The actual shear force of the lean part under the optimal conditions was 3887.21 g,which was significantly lower than the shear force of the untreatment group(7629.16 g)by 49.0%,and also lower than the shear force(4663.42 g)of the single papain treatment group by 16.6%.In addition,the microstructure of the cross section and the longitudinal section of the lean part indicated that papain tenderization assisted by ultrasonic can improve the tenderized uniformity and have a better tenderization effect on the beef.Secondly,the effect of low temperature sterilization on the microbial load and quality of stewed beef was investigated.Sterilization effects of low frequency microwave,radio frequency and water bath were studied and the conditions with better comprehensive effects of every sterilization technology were selected.In order to improve the sterilization uniformity,microwave and radio frequency were combined with water bath respectively to sterilize the stewed beef.Effects of different sterilization conditions on the texture,color and other quality attributes of stewed beef were discussed.The results showed when combining with water bath,radio frequency and microwave had obviously improved sterilization effects.And radio frequency sterilization combined with water bath had little effect on the product quality.Considering the comprehensive effects,radio frequency 30 mm,30 min+water bath90?,10 min was chosen as the best conditions of low temperature sterilization of stewed beef.Thirdly,the quality changes of sterilized stewed beef during storage at 4? was studied.The shelf life of stewed beef during storage at 4 ? predicted by Gompertz equation was 203days.During this shelf life,the pH,color,texture,lipid oxidation,seneory evaluation and microbes of stewed beef presented good storage stability.Compared with the samples sterilized by high temperature 121?,20 min,samples sterilized by radio frequency 30 mm,30 min+water bath 90?,10 min showed a slower speed of quality deterioration during storage,indicating that low temperature sterilization can better maintain the sensory and nutritional quality of the stewed beef.Finally,the influence of microwave reheating conditions on the quality of stewed beef was investigated.First,fluorescence optical fiber thermometer was used to explore the reheating uniformity of microwave and water bath 100? and the result showed that the uniformity of microwave reheating is better.The sample reheated by traditional 100?-10 min water bath was set as the control,and the effects of five different microwave reheating conditions(700 W-60 s?595 W-80 s?595 W-110 s?465 W-110 s?465 W-140 s)on the production rate,water content and other indicators of stewed beef were discussed.Finally,595 W-75 s and 462 W-105 s were chosen as the optimal microwave conditions to reheat stewed beef and can better replace the traditional reheating method of 100? water bath.