Effects Of Controlled Freezing-point Storage And Green Preservation On Chilled Pork Preservation

Chilled pork is taking up a growing market,which is the main direction of the supply and consumption of fresh meat in the future.In the process of production,transportation,storage and sale,chilled pork is easy to contaminate microbes and cause spoilage,which affects food safety.The research on prolonging the shelf life of chilled pork and maintaining the quality of chilled pork has become the trend of meat science in China.Although chemical synthetic preservative have high antiseptic and fresh-keeping effects,they often bring adverse effects to human health.Natural preservatives,including milk-derived antimicrobial peptides,have low dosage and good anticorrosive effect,and have good prospects for development.Controlled freezing-point storage is considered to be the third generation of preservation technology after refrigerated storage and controlled atmosphere preservation.At present,the research of controlled freezing-point storage technology is mainly focused on aquatic products,but the application in meat preservation is less.The dominant spoilage bacteria of chilled pork are different in different freezing process.It is of guiding significance for the preservation of chilled fresh pork to study on the variation of spoilage bacteria.This paper mainly studied on the selection of the optimum pork preservation temperature and the use of preservatives,optimization of preparation process of clove essential oil microcapsules and its effects on preservation of pork under ice-temperature,effects of single and compound natural preservative on preservation of chilled pork and establishment of a near-infrared spectroscopic model for detecting the total viable counts of certain spoilage bacteria.The main work and research results are as follows:(1)According to the freezing curve of fresh pork,the freezing point of fresh pork was determined to be-1.5?.The changes of sensory,drip loss,pH value,TVB-N and the total viable counts of fresh pork at 4?,0?and-2?were compared.Finally,-1?~0?was selected as preservation temperature of pork after taking all the freshness indexes above into consideration.(2)Three ways of using preservation of pork including spraying,smearing and soaking were compared.It was found that there was no significant difference between the three methods.Considering economy,simple and convenient,the pork samples were treated by smear.(3)Microcapsules of clove essential oil(CEO)were prepared through complex coacervation and the embedding rate was taken as the evaluation index.Based on the single factor test,the microencapsulation technique was optimized by using Box-Behnken center combination test and response surface methodology.The model was of great difference,and the established regression equation for embedding rate of CEO microcapsules had an excellent goodness of fit.Therefore the embedding rate of CEO microcapsules could be analyzed and predicted by the model.The optimum preparation technology of CEO microcapsules was also obtained.The highest embedding rate of CEO microcapsules prepared in study could reach 84.20%,and it could prolong the storage period of pork significantly under ice-temperature.(4)The effects of antibacterial peptides derived from goat milk and compound natural preservative 3~#on chilled pork preservation were studied.The results showed that antibacterial peptides derived from goat milk had a certain inhibitory effect on five common spoilage bacteria under the condition of ice temperature,but the effect was not obvious.The compound preservative had a strong inhibitory effect on five common spoilage bacteria,and had a significant inhibitory effect on lactic acid bacteria.(5)Using fourier transform near infrared spectroscopy(FT-NIR)combined with partial least square method(PLS),the quantitative analysis models of the total viable counts,Pseudomonas and B.thermosphacta of chilled pork were established.The results show that there was a good linear relationship between the fourier transform near infrared spectrum after signal vector normalization(SNV)pretreatment and the total viable counts of chilled pork,and the prediction ability of the model was good.There was a good linear relationship between the fourier transform near infrared spectrum signal after multivariate scattering correction(MSC)pretreatment and Pseudomonas of chilled pork,and the prediction ability of the model was good.