低温高湿变温解冻提高羊肉的品质

Low-variable temperature and high humidity thawing improves lamb quality

为了研究低温高湿变温解冻对羊肉品质的影响,该文研究了低温高湿变温解冻工艺(试验组,解冻温度为2℃→6℃→2℃,相对湿度RH>90%)和空气自然解冻工艺(对照组,控温4℃)对羊肉解冻过程中品质变化的影响。分析试验组与对照组羊肉在解冻过程中的色泽、蒸煮损失、解冻汁液流失、汁液蛋白含量、肌肉蛋白表面疏水性以及质构特性等的变化,应用扫描电镜(scanning electron micrograph,SEM)研究不同解冻工艺对肌肉微观结构的影响,结合SDS-PAGE电泳分析不同解冻工艺对肌原纤维蛋白组分变化影响及蛋白的交联、降解效应。结果表明:试验组与对照组相比,羊肉解冻后蒸煮损失率、解冻汁液流失率、汁液中蛋白含量及肌肉蛋白表面疏水性分别降低了3.59%,4.0%,8.98%,97.44(P<0.05),肉色更新鲜,硬度及咀嚼性也高于对照组;SDS-PAGE及SEM观察研究结果表明,不同的解冻方法都会导致解冻过程中肌肉蛋白的交联与降解,但试验组解冻羊肉与对照组相比,肌肉的微观结构遭破坏程度较轻,肌纤维束较对照组完整。与生产中常规使用的空气自然解冻相比,低温高湿变温解冻法能显著降低羊肉解冻过程中的品质劣变,提高解冻羊肉的品质。

The effects of a low-variable temperature and high relative humidity thawing method （LVTHRHT） test group, thawing temperature 2℃→6℃→2℃, RH〉90%） and a conventional air thawing method （control group, thawing temperature 4℃） on the quality of lamb hindquarters were investigated in this paper. The indexes including color, cooking loss, thawing loss, protein content of thawing drip, texture profiles analysis （TPA） of thawed hindquarter and surface hydrophobicity of myofribrillar protein were measured. The microstructures of the transverse section of frozen and thawed samples were observed by scan electric microscopy （SEM）. The effects of different thawing methods on the component, aggregation and degradation of myofibrillar protein were studied by SDS-PAGE gel electrophoresis. The results show that LVTHRHT could significantly decrease （P〈0.05） cooking loss, thawing loss, protein content of thawing drip, and surface hydrophobicity of myofribrillar protein, and significantly increase （P〈0.05） lightness L＊ value, redness a＊ value, hardness and chewiness.However, there were no significant （P〉0.05） effects on yellowness b＊ value, springiness and gumminess; the results of SDS-PAGE gel electrophoresis. SEM showed that both of the thawing methods could result in aggregation and degradation of myofibrillar protein, and damage the microstructure of muscle. While the microstructure of muscle fiber bundles of control group was damaged more seriously, the air thawing method tore more muscle fiber bundles and exhibited a visibly larger gap between muscle fibers compared to the LVTHRHT. Compared to the most common thawing method （in air at 4℃）, there were many advantages of the LVTHRHT method： preventing the loss of the surface water and significantly decreasing thawing loss, cooking loss, nutrition loss （protein）; formation of water film to prevent oxidation of meat, retarding the deterioration of lamb quality, and the physicochemical characteristics of the thawed lamb were closer to fresh meat.This new thawing method requires only a slight change to the existing 4℃ defrost garage： installing steam pipes to the defrost garage used for increasing the temperature and humidity of the defrost garage to realize high relative humidity thawing. Installing frequency refrigeration fan used for decreasing the temperature of the defrost garage, the combination of hot steam pipes and frequency refrigeration fan could realize LVTHRHT. Besides, installing temperature sensors and humidity sensors to monitor the temperature and humidity of a defrost garage, when temperature was higher than 6℃, the frequency refrigeration fan stared to work until the temperature reached 2℃. When the temperature was lower than 2℃, the hot steam system started to work until the temperature reached 6℃. When the relative humidity was lower than 90%, the hot steam system started to work until the relative humidity reached 90%. Coordination of the two systems would ensure that during the entire thawing process, the temperature was between 2℃ and 6℃, and the humidity was greater than 90%. The LVTHRHT could significantly prevent the deterioration of lamb quality, and it was low cost and easy to operate. This research provides a theoretical basis to apply the LVTHRHT method in production and indicants a promising application potential for LVTHRHT in the thawing of frozen meat.