Influence Of MAP Methods On Meat Color Of Different PHu Beef

Beef color is the most important attribute that influences customer’s decisions when purchasing fresh meat at the point of sale because consumers use meat color as an indication of freshness and wholesomeness.Therefore,maintaining the attractive red color and color stability of fresh meat has a very important significance.Dark-cutting beef color is an important and old meat quality issue which has been attracting the attention of many scholars,because the dark lean color of dark cutting beef does not meet expectations for beef product appearance and thus,is discriminated against by consumers.Modified atmosphere packaging technology has been applied in fresh beef to promote meat color and protect meat from microbial spoilage for a long time,however,to our knowledge,few have provided with the information on MAP of dark-cutting beef.Research was undertaken to determine the influence of different modified atmosphere packaging on color stability,and determine if one of the current common retail packaging methods be suitable for color development of intermediate pH or dark cutting meat.In this experiment,12 beef carcasses（Luxi×Simmental with similar age and weight）were selected from a commercial abattior.On day 2 postmortem,beef cattles were divided into three groups according to the ultimate pH value,divided samples in 3 group:low pH value group（5.40<pH≤5.80）,intermediate pH value group（5.80<p H≤6.10）and high pH value group（pH>6.10）.The longissimus lumborum（LL,12th rib to the last lumbar vertebrae）on both sides of each animal were removed,vacuum packaged and transferred to the lab within 4 h.Then beef steaks were individually packed in either HiOx-MAP（80%O₂,20%CO₂）,CO-MAP（0.4%CO,30%CO₂,69.6%N₂）,or vacuum packaging.The packaged steaks were stored at 2℃for 20 days in the dark,samples were removed at 0,4,8,14,20 days for physicochemical analysis.The main results of this study are as follows:1.To low pH value group and intermediate pH value group,pH values showed no significant differences among packaging treatments.While high pHu steaks in CO-MAP had significantly decreased p H values during storage time.Along with the pHu values increased,the purge loss of steaks decreased significantly,and the steaks with vacuum packaging had a higher purge loss than those packaged in HiOx-MAP and CO-MAP.So packaging methods had little influence on pH values of beef,and MAP was helpful to maintain the water-holding capacity of beef.2.Compared with vacuum packaging,steaks in CO-MAP and Hi Ox-MAP had significantly increased L*values and a*values.The meat color of intermediate pHu and high pHu beef packaged in CO-MAP and HiOx-MAP was similar to the color of normal pHu beef after 4 days’storage time.3.Steaks of each pHu group had significantly increased content of MetMb from day 0 to day 8.The steaks of low pHu group dad a higher content of MetMb than high pHu and intermediate pHu group,and there was no difference between high pHu and intermediate pHu group.The steaks in HiOx-MAP had higher content of MetMb than those in CO-MAP and vacuum packaging.4.Along with the pHu values of beef steaks increased,metmyoglobin reducing activity trend to increase.In addition,steaks of high pHu and intermediate pHu group had a higher MRA than those of low pHu group.Steaks with vacuum packaging and CO-MAP maintained higher metmyoglobin reducing activity during storage time,while HiOx-MAP significantly decreased the MRA of steaks.The TBA values of steaks in vacuum package and CO-MAP had no significant change after 4 days of storage time,and there was no difference between these two packaging methods,while those in HiOx-MAP had an increasing trend during storage time.Steaks of high pHu and intermediate pHu group had a lower TBA values than low pHu steaks.The results indicate that high pHu beef had a wonderful color stability because of the higher MRA and lower thiobarbituric acid reactive substances values.