Enzymatic Modification Of Gelatin Gels And The Application In Steamed Dumplings And Yao Meat

Traditional foods represented by Chinese flour food and Chinese cooked meat products have an important position in our food industry and are deeply loved by consumers.However,in the process of traditional food industrialization,the food company often encounter some challenging problems that need to be solved urgently.It requires closer integration of production,education and research,and technology to transform and upgrade the traditional food industry.The same problem occurred in the production of steamed dumplings and Yao meat,which is the gelatin gel melting: Melting of gelatin gel in steamed dumpling fillings would make dumpling making impossible,and melting of gelatin gel in medium during thermal sterilization would destroy the appearance and taste,hinder the subsequent sterilization and the shelf-life prolonging.The project aimed to solve the stability of gelatin gels and the preservation of Yao meat.After enzymatic modification of these gelatin gels,the gelling process of modified gelatin gels and the effects on gel characteristics and microstructure were researched from the perspective of reaction kinetics.The nanoemulsion-based active coatings with composite natural antimicrobials combined with pasteurization was used to improve product quality during storage of modified Yao meat.Besides,the storage test of modified steamed dumplings was conducted,for the application of these modified gelatin gels in two products.Main research contents are as follows:Firstly,the modified method was determined as transglutaminase,by studying the effects of two modification methods(transglutaminase and polysaccharide colloids)on the melting point of gelatin gel,the viscosity of steamed dumpling soup,and the sensory quality of steamed dumpling fillings.The optimum modification conditions of gelatin gel in steamed dumpling fillings were determined by investigating the influence of enzyme modified conditions on the melting point of gels: enzyme addition was 0.5%(w/w),enzyme reaction time was 40 min,and enzyme reaction temperature was 45°C.The melting temperature was raised to 39.759? and it passed the test of application effects in steamed dumplings.Yao meat with the same melting problem was also modified by enzyme.The optimum modification condition of gelatin gel in Yao meat was determined by evaluating the melting point and texture of gels: enzyme addition was 1.0%(w/w),enzyme reaction time was 40 min,and enzyme reaction temperature was 45°C.The melting temperature was raised to 78.142? and this enzymatic modification process also passed the test of application effects in products.Secondly,the effects of transglutaminase modification conditions on the gelation kinetics and key gel properties of gelatin gels were studied.The mechanism that enzymatic modification conditions influenced key gelatin gel properties was verified,by correlation analysis between kinetic parameters and gel properties(texture,water holding capacity,and melting point)and the observation of gel microstructure at different gelation rates: the effects of modification conditions on final properties of gelatin gels could be achieved by changing the dynamics that directly affected gel structure.Finally,the storage problem of Yao meat products after application of modified gelatin gel was solved by antibacterial and sterilization treatment,and the storage test of modified steamed dumplings was conducted.After selecting the types of antibacterial through determining minimum inhibitory concentration(MIC)and fractional inhibitory concentration index(FICI),the orthogonal test was used to determine the formula with the best bacteriostatic effect: the mass ratio of star anise essential oil,polylysine and nisin = 6:1:2.The verification experiment results showed that the antibacterial rate against the mixed bacteria of Yao meat is as high as 96.02%.The composite antibacterial was prepared as nanoemulsion by ultrasonic emulsification.The optimal preparation process was defined by investigating mean droplet size and polydispersity index(PDI).Compared with chemical antibacterial,single natural antibacterial and ordinary emulsion containing composite antibacterial,the nanoemulsion has the highest antibacterial rate(97.06%).Combination of nanoemulsion-based active coatings and pasteurization was applied to Yao meat and the storage test was conducted.The results showed that during the 28-day storage,the combining preservation was most beneficial of maintaining physicochemical,microbiological,and sensory properties of products.The shelf life of products was extended to 24 days.Besides,the storage test of modified steamed dumplings was conducted and results showed that the enzymatic modification of gelatin gels with optimum condition had no significant effect on the prroduct quality of steamed dumpling during frozen storage.