鳝鱼肉新鲜度对加热过程中蛋白变化规律的影响

以不同新鲜度（4 ℃下贮藏1、2、3、4、5 d）的鳝鱼肉为原料，研究其加热过程中蒸煮失水率、化学作用力以及蛋白结构的变化规律与差异，探讨贮藏过程中鳝鱼肉品质劣变机制。结果表明：低新鲜度鳝鱼肉在贮藏过程中蛋白发生降解，导致加热过程中蒸煮失水率更高；加热过程中，鳝鱼肉蛋白间离子键和氢键随加热进行逐渐被破坏，疏水作用和二硫键逐渐成为主要作用力；贮藏1～2 d的鳝鱼肉在加热过程中，疏水相互作用含量增加，二硫键含量在加热前期逐渐增加，后期变化不大；贮藏3～5 d的鳝鱼肉在加热后期疏水相互作用和二硫键含量降低；蛋白结构变化分析表明，新鲜度较差的鳝鱼肉，蛋白二级结构随着加热进行展开程度增加，且疏水基团更倾向于包埋在内部，与疏水作用变化趋势一致。综上：贮藏时间较长的鳝鱼肉在加热过程中蛋白更容易降解、二级结构展开和疏水基团的包埋程度更高，导致疏水作用和二硫键含量的降低，进而造成熟化鳝鱼肉蒸煮失水率高，质构品质劣变。本研究结果为不同新鲜度鳝鱼肉熟化后品质劣变机制的阐明提供了初步理论参考。

Effect of Freshness of Monopterus albus on Protein Changes during Heating

Monopterus albus with different freshness (stored for 1, 2, 3, 4 and 5 days at 4 ℃) was used to investigate the changes of moisture loss, chemical forces and protein structure during heating and to explore the mechanism of quality deterioration during storage. The results indicated that protein degradation took place in low-freshness Monopterus albus, resulting in a higher rate of moisture loss during heating. During heating, ionic bonds and hydrogen bonds in Monopterus albus proteins were gradually destroyed, and hydrophobic interaction and disulfide bonds gradually became the major forces. When heating Monopterus albus stored for 1–2 days, hydrophobic interaction gradually increased, while disulfide bonds gradually increased at the early stage of heating and then did not change significantly at the late stage. Hydrophobic interaction and disulfide bonds in Monopterus albus stored for 3–5 days were reduced significantly at the late heating stage. The analysis of protein structure showed that the degree of protein unfolding in low-freshness Monopterus albus increased during heating, and hydrophobic groups were more likely to be buried inside, which was consistent with the trend of hydrophobic interaction. In conclusion, Monopterus albus with a longer storage time was more prone to protein degradation with a greater degree of protein unfolding and greater burying depth of hydrophobic groups, resulting in a reduction in hydrophobic interaction and disulfide bonds, consequently a higher rate of moisture loss and texture deterioration. This study provides preliminary theoretical support for the clarification of the mechanism of quality deterioration of Monopterus albus with different freshness after cooking.