| The rise of prepared dishes not only caters to the fast-paced lifestyle of modern people,but also gives consideration to the concept of nutrition and health.The emergence of the central kitchen further promotes the industrialization process of Chinese prepared dishes.At present,the prepared dishes are faced with the problems of mechanical damage,color change,water loss,protein oxidation,as well as the corruption caused by microorganisms in the process of food distribution and storage.In this paper,the central kitchen Yangzhou pork meat patties dishes were researched.In-depth exploration of the processing mechanism and quality control in central kitchen of raw materials,coupled with coating technology to develop processing means to improve the shelf life of prepared dishes,and combined with artificial neural networks to achieve visualized and intelligent monitoring of product quality during distribution.Pork,shrimp and carrot were processed into main material of Yangzhou pork meat patties dishes(meatballs).Compared with vacuum frying(VF),the effects of ultrasound assisted microwave vacuum frying(UMVF)on the oxidation of frying oil and the quality characteristics of meatballs were studied.The quality control mechanism of meatballs during frying was revealed by correlation analysis.Compared with VF,UMVF can slow down the oxidation of frying oil,inhibit the increase of acid value,polar components and peroxide value,slow down the increase of color and viscosity;the meatballs obtained by UMVF have lower protein carbonyl and TBARS contents;through the correlation analysis of frying oil index and meatball index,the quality of frying meatballs was significantly positively correlated with the quality of frying oil.In order to facilitate the subsequent processing of central kitchen dishes,the quality control of meatballs during frozen storage by ultrasound combined with chitosan/sugar alcohol nano-water retaining agent(WRA)was studied.The results show that the average particle size of the WRA was 295.3 nm,the thawing loss rate and the transverse relaxation time of water distribution in the tissue of frozen meatballs were reduced by chitosan/sugar alcohol water retaining agent combined with ultrasonic treatment(WAR-US);the increase of TVB-N content and the deterioration of texture quality of pork were delayed by WAR-US 60W.The content of ascorbic acid and carotenoid of carrot in meatballs decreased,and the nutritional quality of meatballs was maintained to a large extent.Taking frozen meatballs as the research object,the effects of different thawing methods on the protein oxidation,solubility and quality characteristics were evaluated,and the quality deterioration mechanism of frozen meatballs was elaborated based on the correlation between the indexes.The results showed that the degree of oxidation of thawed meatballs at room temperature was the most serious(carbonyl content was 9.32%),the protein and lipid peroxidation could be delayed by radio frequency thawing and cold storage thawing;the total number of colonies,TVB-N and TBARS values of radio frequency thawed meatballs were the smallest,and the water distribution,nutrient content and microstructure were well maintained;the protein and lipid oxidation reactions occurred during the thawing process of meatballs,accompanied by solubility of muscle protein.In order to reveal the effectiveness and applicability of anise essential oil/cinnamaldehyde coating solution(HE)for extend its shelf life in storage,the antibacterial mechanism of the coating liquid on microorganisms was studied from the microstructure of the bacteria,the structure of the cell wall,the permeability of the cell film and the enzyme activity in the cell,and the effect on the quality characteristics of the dishes during storage was also compared.The results covered the facts that the HE coating liquid exhibited a lower particle size and PDI,a higher potential,and the system appeared as a shear thinning fluid;The particles were translucent and evenly distributed in the fluid and their surfaces were smooth;The thermal stability of the system was also significantly improved.Escherichia coli and Staphylococcus aureus were used for the antibacterial test strains,and we found that their growth obviously inhibited by coating liquid,and the cell film and cell wall of the bacteria were destroyed.The coating liquid could effectively inhibit the growth of microorganisms(total number of colonies,yeast and mold)in Yangzhou Pork meat patties dishes,delayed the increase in TVB-N content and TBARS value,maintained product nutrients,structural characteristics and sensory quality,and thus extended Yangzhou Pork meat patties dishes shelf life from 4 d to 7 d.For further improving the antibacterial performance of the above-mentioned coating liquid,porous starch(PS)was used as a carrier to adsorb anise essential oil/cinnamaldehyde(FC),and sodium alginate(SA)was applied for the wall material,and glutaraldehyde was used as a curing crosslinking agent.SA/PS-FC coated particles were prepared by them and then blended with chitosan to construct a CS/SA-PS-FC sustained-release system to evaluate the applicability of the system to extend the shelf life of Yangzhou Pork meat patties dishes.The results showed that FC was encapsulated in the CS/SA-PS-FC slow-release system,and this slow-release system could improve its thermal stability.In an open environment,the 12-day cumulative release rate of FC was 70.62%,but in a closed system,the release rate was 43.87%.Fitting the Avrami equation R~2 is greater than 0.9,which explained the release characteristics of the system from the aspect of sustained release kinetics.The CS/SA-PS-FC system could effectively delay the oxidation of fat and protein and the degradation of nutrients in Yangzhou Pork meat patties dishes,and inhibit the increase of colonies,TVB-N value and the content of metmyoglobin,and maintain the good texture characteristics and water distribution of the dishes to extend the shelf life of the dishes from 4 d to 9 d.For realizing the visual and intelligent monitoring of the quality of the Yangzhou Pork meat patties dishes in the central kitchen,zein(Z)and SA were used as the film-forming substrate,and glycerin(G)was selected as plasticizers,and raspberry anthocyanin/curcumin(RA)were applied as a natural indicator to prepare a p H-responsive film,and an intelligent predictive model for real-time quality monitoring in the delivery process was established based on an artificial neural network.The results displayed that the addition of plasticizers weakened the intermolecular and intramolecular forces between SA and Z,and formed a new hydrogen bond;The section of Z/SA-G film was uniform and dense,slightly rough but without holes and faults,the addition of G effectively improved the thermal stability of the Z/SA film;The water vapor transmission rate,mechanical properties of the film,cross-sectional compatibility and the stability of the film itself were benefits for the indicator film with RA,and the response to different p H values was obvious.After 9 day-storage of Yangzhou pork meat patties dishes,the color of the film changed from dark red to lavender,and finally to blue-brown.At this time,the value of colonies,TVB-N and TBARS was 4.58 log(CFU/g),17.56 mg/100 g,0.601 mg/kg,respectively,all these indicated that the Pork meat patties dishes have begun to spoil.The BP-ANN prediction model was established based on the different color changes of the indicator film.The model could cover the internal laws of the three variables affecting the changes in sample quality,and achieve real-time data acquisition of product quality. |
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