Effect Of Storage And Transportation Environment On The Quality Of Chilled Pork And Its Mechanism

Chilled pork is one of the main sources of protein,which is also an important meat on the table of Chinese consumers.Due to the factors such as rich nutrition,high moisture content and oozing of juices in the meat,chilled pork is also a good place for microbial growth and reproduction.Therefore,the urgent problem for the pork industry is to effectively control the growth of microorganisms and maintain the quality of chilled pork products.The storage and transportation of cold chain logistics is a necessary link in the chilled pork industry.Although it takes a relatively short time,the cumulative effects of microorganisms in this process and the resulting product spoilage and flavor changes cannot be ignored.This study took chilled pork as the research object,simulating various environmental conditions in the 3 days of storage and transportation of cold logistics.Using physical and chemical,microbiological,sensory and other evaluation indicators combined with microbial high-throughput sequencing technology and GC-IMS technology to explore the impact of storage and transportation environment on the quality of chilled pork,bacterial diversity and volatile flavor compounds.And this study further explained the internal mechanism of the impact of the storage and transportation environment on the quality of chilled pork from the perspective of myofibrillar protein oxidation and degradation.The results of the study were as follows:(1)A study on the influence of storage and transportation environment(temperature,humidity,gas,vibration intensity,and control technology of initial microbial)on the freshness and quality of chilled pork was carried out,and the results showed that: storage and transportation environmental factors had a significant impact on the freshness and quality of chilled pork(p<0.05).The higher the ambient temperature was,the faster the spoilage rate of chilled pork was,and the total number of colonies in the high-temperature environment sample(10 ?)closed to the critical point of spoiled meat on day 3.The carbon dioxide packaging of 100% could obviously inhibit the growth of chilled pork microorganisms,oxygen gas packaging of 100% could keep the flesh color,though the nitrogen gas packaging of 100% and vacuum packaging had a negative impact on the quality of chilled pork.The low-humidity environment could obviously inhibit the increase of microorganisms,while the high-humidity group was significantly better than other groups in terms of smell,color,and tissue state,which was more conducive to pork quality.The high-intensity vibration in the logistics process increased the flexibility,and enhanced the loss of juice,which accelerated the deterioration of the quality of chilled pork.Antibacterial treatment of electrolyzed oxidizing water could effectively reduce the initial number of microorganisms,inhibit the proliferation of microorganisms,delay the increase of TVB-N value and p H value,and maintain the quality of chilled pork.It is recommended that the environment be controlled at 0 ? 7 ? with high humidity for storage and transportation of chilled pork,and the time should be set within 2 days.(2)Based on the microbial high-throughput sequencing technology,the research on the influence of different storage and transportation environmental factors on the diversity of the surface flora of chilled pork was carried out,and the results showed: the lower the environmental temperature,the slower the growth rate of the dominant flora in the sample and the richer the diversity of the flora.Under different gas packaging,the microbial flora structure in chilled pork has changed significantly,and the carbon dioxide packaging of100% could effectively reduce the abundance of the main spoilage microorganisms in pork such as Pseudomonas and Cyclophaea.Environmental humidity also had an impact on the structure and abundance of the flora.The diversity of chilled pork flora decreased,and the flora structure changed significantly under low-humidity environment at the end of storage.The intensity vibration in the logistics process had little effects on the microbial flora structure of chilled pork.Antibacterial treatment of electrolyzed water could effectively reduce the abundance of spoilage microorganisms such as Pseudomonas and Cyclophagus.But Pseudomonas became the dominant flora in each group of samples in the later period.(3)Based on the changes in the biochemical characteristics of myofibrillar protein,the mechanism of the response of chilled pork quality to the storage and transportation environment was explained,and the results showed that: the quality of chilled pork decreased,and the volatile flavor substances such as amines,alcohols and aldehydes significantly increased during storage.With the prolongation of storage time,the carbonyl content and surface hydrophobicity of pork myofibrillar protein were increased,but the total sulfhydryl content was decreased.Large molecular weight proteins between 37 k Da and 52 k Da were degraded into small molecular weight between 30 k Da and 37 k Da.The?-helical structure turned into ?-sheet,and the disordered structure increases in myofibrillar protein.However,the biochemical properties of myofibrillar protein were different between different groups.The secondary structure of myofibrillar protein was effectively maintained in the lactic acid treatment group and the high humidity group.Antibacterial treatment of electrolyzed water could slow down the oxidation of myofibrillar protein during the initial storage period.