Effect Of Low Energy Electron Beam Treatment Combined With Superchilling On Quality And Shelf Life Of Chilled Pork

As the main direction of fresh meat supply and consumption,chilled pork is occupying more and more shares of the meat market.Many technologies have been tried to increase the shelf life of chilled pork in recent years,but the industry's fast growth is still hindered by its short shelf life.Superchilling can extend the shelf life of food while reducing the damage to quality.As a non-thermal sterilizing method,electron beam irradiation may kill bacteria without causing significant thermal damage.However,high energy electron beam treatment(5 ? 10 Me V)is presently employed in meat processing,and this can have a considerable influence on meat sensory quality and nutritional value.This study combines low energy electron beam treatment(0.2 Me V)with superchilling to limit microbical growth and reproduction in chilled pork while maintaining sensory quality and prolonging shelf life,as well as offering technical assistance for pork storage and preservation.In this study,the longissmus dorsi muscles of pork was selected as experimental material.The longissmus dorsi muscles was break up into 1.5 cm thick pork steaks and vacuum packed.Steaks were randomly and separately treated with low energy electron beam.After above treatments,these materials were divided into 2 groups again,which were stored at superchilling(-1 ± 0.5?)and chilled(2 ± 2?).Many indicators were measured at each storage time point.The above indicators were used to investigate the effect of low energy electron beam treatment combined with superchilling on the quality and shelf life of chilled pork.The following are the study's key findings:(1)Low energy electron beam treatment combined with superchilling was able to improve the meat color and significantly increased the L*,a*,and b* values of chilled pork(P < 0.05).This treatment reduced the relative content of metmyoglobin and increased the relative content of oxymyoglobin during storage of chilled pork.Superchilling is benefit for delaying meat color browning and improving the stability of meat color.(2)Low energy electron beam treatment combined with superchilling significantly reduced the total viable count of chilled pork(P < 0.05).After 20 days of chilled storage,the total number of colonies in the 0 k Gy group had exceeded 7 log CFU/g,reaching a spoiled state,and the TVB-N value exceeded the national limit standard(15 mg/100 g).When stored at superchilling until 30 d,the total viable count and TVB-N value of pork in the 8 k Gy and12 k Gy treatment groups did not exceed the limit,and the shelf life was significantly extended.The relative abundance of Photobacterium decreased after low energy electron beam treatment.At the same time,the relative abundance of Glutamicibacter,Kosakonia and other bacteriawere elevated,which also increased bacterial diversity.Therefore,the reduction in the total viable count at the beginning of the low energy electron beam treatment may be achieved by killing the Photobacterium.Low energy electron beam treatment altered the microbial community succession during storage,producing an inhibitory effect on Carnobacterium and Lactobacillus.The conformation of the flora of each treatment group at 20 d of superchilling storage was similar to that at 10 d of chilled storage.This suggests that superchilling may have slowed down the process of chilled pork spoilage.Photobacterium was the majority bacteria in the 8 k Gy group after 30 days of storage under superchilling storage conditions,whereas Lactobacillus was the dominant species in chilled storage.This suggests that the low energy electron beam treatment in combination with superchilling exerted a better bacterial inhibition effect,which mainly attributed to the superchilling storage inhibited the activity of Lactobacillus.(3)The degree of lipid oxidation and protein oxidation were elevated after low energy electron beam treatment.Nevertheless,the TBARS values did not exceed the safety limit of0.664 mg MDA/kg in any group.Therefore,it was unnecessary to consider the negative effects of lipid oxidation on the quality of chilled pork after low energy electron beam treatment.(4)After the low energy electron beam treatment,the meat color was improvedand,and the appearance score also significantly improved.The odor,texture and overall acceptability of the 0 k Gy group were better than the 8 k Gy and 12 k Gy groups at the beginning of storage.With the extension of storage time,the odor dissipated and the color brightened in the 8 k Gy group which gradually reach a good sensory quality.However,due to the higher dose,12 k Gy group had a irradiated heavier odor which was difficult to dissipate,and reduced the meat elasticity.Compared with chilled storage,pork in the 8 k Gy treatment group stored at superchilling was more acceptable to consumers and had higher commercial value.After comprehensive comparison of meat color,shelf life and sensory quality.8 k Gy low energy electron beam treatment combined with superchilling had the best effect which could significantly improve the meat color of chilled pork,delay browning and extend the shelf life of storage.It plays a positive role in maintaining the sensory quality of chilled pork,such as odor freshness,appearance,texture,and its production becomes more acceptable to tasters.