Effects Of Barrier Packaging And Low-voltage Static Electric Field Technology On Pork Meat Quality

Fresh meat is prone to spoilage in the preservation process. With the increased demand for high quality,safe,and extended shelf life of fresh meat products,fresh meat packaging is commonly used in meat industry. The packaging process and storage conditions are one of the most important processes among all the food manufacturing processes. This study investigated the impact of barrier package including vacuum shrink packaging and MAP packaging on pork quality,and combined the low-voltage static electric field(LVSEF) and high-oxygen modified atmosphere packaging in order to extend the shelf life of chilled meat and improve its quality,then the research studied the influence of LVSEF on the freezing and thawing processes of pork meat. The results were as follows:In order to demonstrate the effects of vacuum shrink packaging on quality of chilled pork meat during storage,two packaging materials with different barrier property were used,comparing with usual tray packaging. The total number of bacteria,TVB-N,surface color,water-holding capacity,tenderness,protein oxidation and myofibril protein myofibril degradation of chilled pork meat was measured. The results suggest that the shelf-life of chilled pork meat with vacuum shrink packaging could be extended 3 days compared with tray packaging; The a* value of shrink packaging group is significantly lower(P<0.05) than the tray packaging group. However,after exposed to air,the a* value significantly increased and became higher(P<0.05) than the other two kinds of packaging group,and the color was bloomed to bright red; The water-holding capacity of vacuum shrink packaging groups is higher(P<0.05) than usual tray packaging,but there was no significant difference between two shrink packaging groups(P>0.05); The degree of meat oxidation in vacuum shrink packaging groups are lower than usual tray packaging group; According to the SDS-PAGE analysis results,there were protein aggregation,degradation and denaturation in chilled pork meat during storage. Protein degradation speed in vacuum shrink packaging groups was greater than the usual tray packaging group. It was concluded that high barrier vacuum shrink packaging can keep higher quality and extend the shelf-life of chilled pork meat during storage.High barrier property materials and two different gas concentration( 80%O2+20%CO2 and 50%O2+20%CO2+30%N2)were used in the MAP packaging,comparing with usual tray packaging. The gas concentration in packaging,total number of bacteria,surface color,water-holding capacity and tenderness were measured. The results suggested that the gas ratio of the MAP groups maintained constant during storage. Low O2 concentration MAP group can prolong the shelf life of fresh pork 6 days compared with the usual tray packaging,and the shelf life of high O2 concentration MAP group was longest; The a* and b *value of the MAP groups is significantly higher(P<0.05) than the tray packaging group. The water-holding capacity of MAP packaging groups is lower(P<0.05) than usual tray packaging,and there was no significant difference between two MAP groups(p>0.05); The shear force value of the MAP groups is higher than the tray packaging group(p<0.05),and shear force value of 80% O2 MAP group is less than 50% O2 MAP group,but the difference is not significant(p>0.05). It was concluded that the MAP groups negatively affected meat quality such as water-holding capacity and tenderness,but it can significantly extend the shelf life of fresh pork meat. And the high oxygen(80%O2+20% CO2) MAP group had more advantages than the low oxygen MAP group.We studied the influence of low-voltage static electric field(LVSEF) on pork meat quality. The meat samples were randomly packaged in polyethylene(PE) trays under air(control),or packaged in EVOH trays under modified atmosphere with 80% O2/20% CO2 with LVSEF((LVSEF-MAP) or without LVSEF(MAP). Total viable count(TVC),surface color,water-holding capacity, tenderness,free animal acid contents,and protein degradation of meat samples were measured during chill storage. The TVC of LVSEF-MAP group was significantly lower than that of control and MAP group(p<0.05). LVSEF-MAP group could keep bright red color for a longer period than MAP group. The drip loss and cooking loss of pork meat in LVSEF-MAP group was lower than other groups. The tenderness of LVSEF-MAP group was improved comparing to MAP group. It demonstrated that LVSEF as a promising and innovative storage technology could improve the quality of fresh pork meat. The LVSEF treatment did not have a significant impact on meat water-holding capacity and tenderness.The freezing and thawing characters of pork meat under the condition of LVSEF and the meat quality after different freezing and thawing process were investigated. The results suggested that the LVSEF extended the freezing time and shortened the thawing time of pork meat. LVSEF significantly reduced the size of the ice crystals in the process of freezing. Pork meat frozen and thawing under the LVSEF condition had the lowest thawing losses compared to other treatments. LVSEF can reduce the loss of protein content in the pork meat drip. LVSEF enhanced pork meat tenderness(P<0.05). Scan and transmission electron microscopes showed LVSEF maintained better cell integrity of pork. NMR analysis showed LVSEF thawing can improve the water retention of pork.