高压静电场解冻减少猪里脊肉汁液损失的机理研究

The thawing process of frozen meat was prone to large thawing loss, reduction in quality, and serious economic loss. The study showed that high voltage electrostatic field thawing could minimize the time through the maximum ice crystal area, reducing the amount of thawing loss and quality deterioration, but the reasons for the mechanism were not clear . The mechanism of reduction in thawing loss of pork tenderloin meat by high voltage electrostatic field was studied from the aspects of water migration and change, internal structure change and protein oxidative denaturation. Firstly, the thawing loss was analyzed by varying electric field parameters and thawing temperature, the changes of water content and the distribution in muscle were studied by low-field nuclear magnetic resonance (LF-NMR), frozen section technique was used to study the change of the distance between the cells and water distribution after thawing; Secondly, the changes of meat texture characteristics were determined by SEM and TEM, analyzing the relationship between the changes of microstructure and thawing loss; Finally, the degree of protein oxidative denaturation, the rheology and gel properties of myofibrillar protein and changes in protein mass fraction in drip loss were determined, analyzing the interaction mechanism with thawing loss. It was a more in-depth understanding of quality changes during high voltage electrostatic field thawing pork tenderloin meat, laying the theoretical basis for industrial application of the healthy, safe, energy saving, time saving new technology.

冷冻肉解冻过程易出现汁液损失大，品质下降，严重经济损失等问题。研究表明高压静电场解冻可以最大程度地减少通过最大冰晶区域的时间，减少汁液损失量，降低解冻过程中肉品质量下降，但机理原因尚不明确。本项目从水分迁移变化规律、微观结构变化、蛋白质氧化变性等方面研究高压静电场解冻减少猪里脊肉汁液损失的机理。首先改变电场、解冻温度等条件分析汁液损失量的变化，利用低场核磁共振研究解冻后肌细胞内外水分具体分布状态，冷冻切片技术研究解冻后肌细胞之间的间距变化及水分分布；其次测定解冻后肉质构特性的变化，通过SEM、TEM研究肉微观结构具体变化，分析与汁液损失之间的相关性；最后测定肉中蛋白质氧化变性程度、肌原纤维蛋白的流变及凝胶特性及汁液中蛋白质质量分数变化，分析与汁液损失之间的相互作用机制。通过研究对高压静电场解冻猪里脊肉品质变化有更深入地认识，为该项卫生、安全、节能、省时新技术的工业化奠定理论基础。

因季节、地域等因素限制，肉品流通贮藏过程中会采用冷冻方式，但冷冻解冻会降低肉品的保水能力，表现为汁液损失，进一步导致感官、嫩度以及色泽变差、蛋白质变性、营养成分流失等现象，从而降低肉品质量。项目主要研究了解冻温度和解冻介质对汁液损失和保水性的影响，分别设置空气解冻温度为4，12，20，30℃，水解冻温度为20，30，40，50℃，利用低场核磁共振技术（LF-NMR）检测解冻后水分分布变化，使用冰冻切片机研究解冻后肉样组织结构，分析水分流失通道及细胞形态变化，利用冷场发射扫描电子显微镜（SEM）观察肉样中肌纤维变化，通过差示扫描量热仪（DSC）测定蛋白质变性程度，利用流变仪测定解冻后肉样斩拌成肉糜的储能模量（G'）和损耗模量（G"）变化，利用质构仪测定解冻后肉样品经过蒸煮后质构特性。结果表明4、20℃空气解冻后汁液损率失少，12、20℃空气解冻后总损失率小。随着水解冻温度的增加，汁液损失率显著性增大（p < 0.05）。20℃水解冻后总损失率最小，保水性好。水解冻时间较短。与鲜肉相比，解冻后肉样的肌细胞之间以及肌束膜内的间距增大，汁液流失通道打开。利用SEM观察到因汁液流失造成肌纤维之间的空隙增大。经过冻结解冻处理后的肉样中蛋白质热稳定性下降，蛋白质发生一定程度的变性。随着水解冻温度的升高，G'和G"呈现增加的趋势。解冻后肌肉蛋白发生一定程度的变性，内部组织结构发生变化，导致肉样蒸煮后硬度增加。解冻后自由水所占的比例（P22）与汁液流失率呈现相关性。空气解冻处理，30℃解冻后猪里脊肉中P22最小，其次分别为20，4，12℃解冻。水解冻处理，20℃解冻后猪里脊肉中P22最小，其次分别为30，40，50℃解冻。解冻温度和解冻介质对肉品中水分分布影响较大。肌肉组织在冻结过程中细胞内外形成冰晶，对肌细胞的结构完整性产生影响，解冻后造成肌细胞内物质流失，因此形成汁液损失。自由水是解冻时汁液流失的直接来源，解冻过程会引起肉品中一部分不易流动水“态变”成为自由水，使得汁液流失率增大。

内容获取失败，请点击重试