Effect Of Ice Temperature And Controlled Atmosphere Packaging On Quality Of Beef During Storage

As a kind of high-protein and high-fat food, beef has been favored by consumers. Withthe improvement of living conditions, the demand of fresh beef is increasing in China.However, fresh beef deteriorates very easily which will not only cause huge economic loss,but also degrade the food safety. Now, the usual freezing method can extend the the shelflife of fresh beef, but when the beef is thawed, its quality deteriorates badly. And thetraditional preservation method ranged from0to4degrees only can keep the beef fresh fora short time. The ice-temperature preservation technology ranged from0degree to freezingpoint can make the beef not be frozen and keep the beef fresh for a longer time. In recentyears, more and more researchers have been devoted to this preservation technology.In thisarticle, we determine the freezing point of fresh beef and researched the effect of icetemperature and controlled atmosphere packaging on quality of beef during storage toensure the optimum technology parameter of keeping beef fresh. Only by this, can weextend the shelf life of beef and decrease the economic loss in the process of logistics.First，we measured the freezing points of different parts of beef, mutton and chicken（foreleg, tenderloin, sinew and rump）through the method of DSC, and measured watercontent, protein content, fat content and other indicators to ensure the correlation of thefreezing point of fresh meat with its components. The results showed that the freezingpoints of beef and mutton ranged from-1.4℃to-1.7℃and the freezing points of chickenranged from-1.1℃to-1.4℃. Besides, the parts of beef which have highest freezing pointare tenderloin and sinew whose freezing point are both-1.4℃. Comprehensive analysisshowed that the freezing point temperature of beef had significantly positive correlationwith water content of beef and had significantly negative correlation with fat content ofbeef. High fat and protein content, especially when the adipose content was high, resultedthe beef had a low freezing point temperature. Therefore, we could predicted the freezingpoint temperature of beef according to the corresponding linear regression equation throughthe determination of fat and water content. Considering the temperature fluctuation ofice-temperature library and the safe storage, we set-2.5℃as the final preservationtemperature.Second, this part studied the quality of beef storaged at-2.5℃、0℃and4℃ice-temperature librarys respectively which have accurate temperature control. Duringstorage, we periodically measured the temperature variation curve of ice-temperaturelibrary and the quality characters including sensory evaluation, TVB-N, total bacteria etc.The results showed that as time went on the sensory quality of beef was decreasing,especially the color and odour. The color of beef changed from bright red to dark redgradually and finally to the crineous. As for the odour, rancid flavor emerged gradually andfoul smell comed into being finally.Besides, the liquid loss rate, TVB-N value, PH valueand total bacteria also increased gradually. The hardness and resilience of beef decreasedfirstly and then increased. The shelf life of beef at ice tempetature (-2.5℃),0℃and4℃were8days,15days and24days respectively,which indicated ice temperature had the bestpreservation effect.Third, this research aimed to obtain the best technological parameters of modifiedatmosphere packaging combined with ice-temperature on the fresh-keeping of beef in theprecise ice-temperature library (-2℃).The different gas composition was2%O2、25%CO2、73%N2，2%O2、50%CO2、48%N2and air respectively. The results showed that theatmosphere of2%O2、50%CO2、48%N2had the best effect of fresh-keeping which couldextend the shelf life of beef to48days. When the beef was stored in this kind ofatmosphere for45days, the color of beef with a slight odor was dark red. The PH value, TVB-N value and total bacteria were6.5,19.85mg/100g,4.8×106cfu/g respectively, stillbelonged to the the secondary fresh meat. However, when the beef was storaged in theatmosphere of air for33days, the beef had bad odor and serious drip loss and the colorchanged from bright red to crineous. When the beef was storaged in the atmosphere of2%O2、25%CO2、73%N2for38days, the beef was as bad as the beef storaged in theatmosphere of air for33days.In total, ice-temperature combined with modified atmosphere packaging could extendthe shelf life of beef effectively. This new preservation technology could be utilized in thestorage, transportation and sales of beef to retain the freshness of beef.