Comparative Analysis of the Quality of Frozen Tibetan Mutton with Different Packaging Materials
To extend the storage period of frozen Tibetan mutton,Tibetan mutton from Qinghai was used as the test material.The total bacterial count,pH value,color stability,water-holding capacity,thiobarbituric acid(TBA)content,peroxide value(POV),and myofibrillar protein oxidation were measured.The quality changes of Tibetan mutton stored at-18 ℃ for 0,3,7,15,30,60,and 90 days were investigated under treatments with different packaging materials:nylon composite bags(PA/PE),polyester composite bags(PE/PET),and seven-layer co-extrusion bags(PA/TIE/PA/TIE/PE/PE/PE).The results showed that compared with standard fresh-keeping bags,the three tested packaging materials,combined with vacuum packaging,had a significant effect on the quality of frozen Tibetan mutton.PA/PE bags could help preserve the quality of the mutton more effectively.After 90 days of freezing,the total number of colonies decreased by 1.7 lg CFU/g in the PA/PE bags compared with the standard storage bags.The pH value was in the range of 6.2～6.6,and the color stability was superior.The cooking loss rate,thawing loss rate,and centrifugal loss rate increased by 4.51％,0.93％,and 2％.The TBA and POV values were significantly lower in the PA/PE bags than the standard storage bags,showing reductions of 0.78 mmol/kg and 0.033 mg/100 g,respectively.The carbonyl content of myofibrillar protein decreased by 1.63 nmol/mg,the sulfhydryl group content decreased by 0.21 nmol/g,and the surface hydrophobicity decreased by 6.74 μg.Comprehensive analyses showed that the PA/PE bag combined with vacuum packaging,while storing at a temperature of-18 ℃,can effectively maintain the quality of frozen Tibetan mutton and prolong its shelflife.
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