低变温高湿解冻对猪肉理化特性、蛋白热变性及流变特性的影响

Effect of Variable Low Temperature Combined with High-Humidity Thawing on Physicochemical Characteristics,Thermal Denaturation and Rheological Properties of Pork

本研究以鲜肉和传统低温(4℃,相对湿度(relative humidity,RH)65%~73%)肉为对照,探究低变温(2℃→6℃→2℃)下,不同相对湿度(80%、85%、90%、95%)解冻对猪肉品质的影响,分析不同处理对肉样解冻效率、保水性、色泽、嫩度、新鲜度等理化特性、蛋白热变性及流变特性的影响。结果表明:相较于传统低温解冻,低变温高湿度可有效提高解冻效率,显著改善猪肉的保水性、色泽、嫩度,显著降低脂肪氧化程度(P<0.05);其中RH 90%、RH 95%条件下解冻效率明显高于RH 80%、RH 85%两组,能有效改善解冻后猪肉的保水性、色泽、嫩度,降低脂肪氧化程度,提高蛋白溶解性,维持猪肉较好的凝胶结构,且猪肉蛋白变性程度显著较低(P<0.05);但RH 95%处理组解冻后猪肉的菌落总数(3.97(lg(CFU/g)))和挥发性盐基氮含量(1.40 mg/100 g)显著高于其他组;且环境湿度越大,能耗就越高。因此低变温RH 90%可作为合适的猪肉解冻条件。

This study was conducted to analyze the effects of thawing at different relative humidity(RH 80%, 85%, 90%and 95%) and viable low temperature(2 ℃→ 6 ℃→ 2 ℃) on the quality characteristics of pork by using fresh pork and conventional low temperature thawing(4 ℃, RH 65%–73%) as the controls. The changes in thawing rate, physicochemical characteristics including water-holding capacity(WHC), color, tenderness and freshness, protein thermal denaturation and rheological properties were examined. The results showed that compared with conventional low temperature thawing,variable low temperature, high humidity thawing could improve the thawing efficiency(P < 0.05), maintain the WHC, color and tenderness of pork, and inhibit lipid oxidation significantly(P < 0.05). The thawing efficiency at RH of 90% and 95%was higher than at RH of 85% and 80%. In addition, viable low temperature thawing at RH of 90% and 95% allowed better maintenance of WHC, color and tenderness(close to fresh pork), reduced lipid oxidation and increased protein solubility.The degree of protein denaturation in the thawed pork at RH of 90% and 95% was significantly lower than at RH of 80%and 85%(P < 0.05) as measured by differential scanning calorimetry(DSC). Also, the thawing at RH of 90% and 95%maintained the G′ value better. However, total bacterial count(3.97(lg(CFU/g))) and TVB-N content(1.40 mg/100 g) in the thawed pork at 95% RH were significantly higher than other thawed samples. Moreover, greater humidity could require higher energy consumption. Therefore, variable low temperature combined with 90% relative humidity thawing was more suitable for frozen pork.