多次冻融对牦牛肉品质及其蛋白质氧化的影响

发布时间：2018-01-08 19:27

本文关键词：多次冻融对牦牛肉品质及其蛋白质氧化的影响　出处：《甘肃农业大学》2017年硕士论文　论文类型：学位论文

【摘要】：牦牛是青藏高原地区特有的牛种,其产地处于平均海拔高度3000 m以上的偏远地区,由于地理因素的制约,在销售、运输以及储藏过程中温度的波动会导致牦牛肉发生反复的冷冻和解冻,冻藏肉在解冻过程中汁液流失与品质劣变十分严重。本文采用甘南玛曲牦牛肉背最长肌为研究对象,样品随机分为8组,每组3份平行,分别为冻融0、1、2、3、4、5、6、7次。分析多次冻融对牦牛肉保水性、蛋白质氧化、抗氧化性的影响,通过多次冻融的处理对牦牛肉营养成分的影响进行分析,通过多次冻融过程对牦牛肉进行组织微观学的测定以及蛋白质二级结构的测定,开展多次冻融过程对牦牛肉蛋白质氧化以及品质影响的机制研究。试验结果如下:1.随着冻融次数的增加,pH、解冻损失、加压失水率和蒸煮损失、钙激活酶活性显著性下降(P0.05),营养成分中的水分和粗蛋白、矿质元素、氨基酸含量显著性下降(P0.05),经过7次反复冻融,肌肉中必需氨基酸的损失大于非必需氨基酸,同时SRC值随冻融次数的增加而逐渐下降。表明多次冻融导致牦牛肉中的汁液流失,嫩度下降,营养品质降低。2.随着冻融次数的增加,肌纤维直径和面积显著降低(P0.05),细胞间隙所占比例显著增大(P0.05),冻融后的线粒体肿胀并空泡化,肌节缩短,Z线错位,甚至消失。表明冻融后其组织结构遭到显著破坏,牦牛肉的品质下降。3.随着冻融次数的增加,肌肉中的羰基含量、蛋白质表面疏水性显著性升高(P0.05),巯基含量、蛋白质溶解度显著性降低(P0.05),表明蛋白质氧化程度随着冻融次数的增加而加强,总酚含量、RSA以及TEAC三者相关性极显著(P0.01),均显著性下降(P0.05),表明蛋白质抗氧化能力随着冻融次数的增加而显著性降低(P0.05)。同时发现保水性与蛋白质氧化性、抗氧化性之间相关性显著(P0.05),表明多次冻融循环引起牦牛肉蛋白质氧化程度加剧,同时造成保水性降低。4.肌肉中蛋白质二级结构随着冻融次数的增加发生了改变,冻融7次后ɑ-螺旋含量下降了62.01%,β-折叠含量上升了45.76%,表明多次冻融会显著破坏蛋白质二级结构。综上所述,贮运体系中避免多次冻融的发生,对保障高品质牦牛肉加工具有重要意义。
[Abstract]:Cattle yak is endemic in Tibetan Plateau and its origin in the average altitude above 3000 m in remote areas, due to the constraints, geographical factors in sales, transportation and storage in the process of temperature fluctuation will lead to yak meat repeated freezing and thawing, frozen meat juice during the thawing process loss and deterioration of the quality is very serious. The Gannan Maqu yak meat longissimus muscle as the research object, were randomly divided into 8 groups, each group of 3 parallel, respectively. 0,1,2,3,4,5,6,7 analysis of freezing and thawing freeze-thaw of yak meat water retention, protein oxidation, antioxidant effect, through the analysis of influence of freeze-thaw treatment the nutritional composition of yak meat, the freezing of yak meat tissue microscopic analysis and determination of protein secondary structure of two financial process, carried out several freeze-thaw process of yak meat products and protein oxidation Study on the mechanism of quality. The results are as follows: 1. with the increase of the number of freeze-thaw pH, thawing loss, pressure loss and cooking loss, calcium activated enzyme activity significantly decreased (P0.05), nutrients in water and crude protein, mineral elements, amino acid content decreased significantly (P0.05) after 7. Repeated freezing and thawing, the loss of essential amino acids than non essential amino acids in muscle, while SRC value decreased gradually with the increasing number of freeze-thaw cycles and freeze-thaw. That resulted in yak meat juice loss, tenderness drops, the nutritional quality of.2. reduced with the increase of the number of freeze-thaw, muscle fiber diameter and area decreased. (P0.05), cell gap proportion increased significantly (P0.05), freeze thawed mitochondria swelling and vacuolization, sarcomere shortening, Z line dislocation, or even disappear. That freeze-thaw after its organizational structure was significantly damaged, yak meat quality decreased with frozen.3. The increase of the number of freeze-thaw, the carbonyl content in muscle, significantly increased the protein surface hydrophobicity (P0.05), sulfhydryl content, protein solubility decreased significantly (P0.05), showed that the degree of protein oxidation increases with the increasing of freeze-thaw cycles, the total phenol content, RSA and TEAC between the three (P0.01), were highly significant significantly decreased (P0.05), indicating that the antioxidant ability of protein increased with the number of freeze-thaw cycles decreased significantly (P0.05). At the same time that the water retention and protein oxidation, oxidation resistance between the significant correlation (P0.05), showed that freezing caused by yak meat protein oxidation increased and thawing, while causing.4. in muscle protein two secondary structure with freeze-thaw cycles increases changed to reduce water retention, after 7 cycles of freeze-thaw alpha helix content decreased by 62.01%, beta sheet content increased by 45.76%, that repeated freezing and thawing significantly damaged protein In summary, it is of great significance to avoid the occurrence of multiple freeze-thaw in the storage and transportation system, which is of great importance to the processing of high quality yak meat processing.

【学位授予单位】：甘肃农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TS251.52

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