摘要
为了研究超高压处理大黄鱼鱼糜的凝胶特性,该文利用低场核磁共振、拉曼光谱研究了水浴加热和超高压处理鱼糜凝胶化过程中水分存在状态和蛋白质结构的变化,并分析了它们和鱼糜凝胶特性指标的相关性。结果表明,与水浴加热处理相比,超高压处理能改善鱼糜凝胶特性,使其保水率、弹性、内聚性增大(P<0.05),硬度下降(P<0.05)。但随压力增大,鱼糜的内聚性、弹性、咀嚼性呈下降趋势(P<0.05),保水率变化不显著(P>0.05);低场核磁共振分析显示超高压使鱼糜自由水组分消失,不易流动水的流动性增强(P<0.05),结合水的含量增加(P<0.05);拉曼光谱分析显示超高压使鱼糜蛋白α-螺旋含量显著增加(P<0.05),无规卷曲和β-转角含量显著下降(P<0.05),三级结构也发生变化;相关性分析表明,蛋白质结构、水分状态及含量与鱼糜的质构、保水率之间存在特定相关性。说明不同处理条件下,鱼糜的蛋白质结构和水分状态发生改变,从而表现出相应的质构、保水率等凝胶特性。以上结果可为鱼糜凝胶特性的评价及改进提供检测方法及理论依据。
To compare the effects of water bath heating and ultra-high pressure processing on the gel properties of large yellow croaker (Larimichthys crocea) surimi gels, we integrated low field nuclear magnetic resonance (Low-field NMR) and Raman spectroscopic technique to analyze the changes of moisture status and protein structure. Meanwhile, we analyzed the differences in traditional characteristic indices of surimi gels such as texture properties, water holding capacity and whiteness to explore their correlation with the variation of moisture status and protein structure. The surimi gels were prepared by heating at 40℃for 1 h and then at 90℃for 30 min in water bath or by high pressure processing at different pressure of 300, 400 and 500 MPa for 30 min. The results showed that surimi gels under high pressure processing had higher water holding capacity, springiness and cohesiveness, but lower hardness compared to heat-induced gels (P<0.05). The cohesiveness, springiness, chewiness and a*of the surimi gels significantly decreased, while the whiteness, L*and b*significantly (P<0.05) increased, when the pressure varied from 300 to 500 MPa. In contrast, water holding capacity was insensitive to the variation of the pressure (P>0.05). High pressure could constrain the mobility of water, resulting in the firm gel network, which was evidenced by the undetectable free water (T23) in the pressure-induced surimi gel. However, high pressure significantly (P<0.05) increased the mobility of movable water and the content of bound water. The increased bound water content was conducive to the formation of gel network, and thereby improved the texture properties and water holding capacity. There was no significant difference (P>0.05) in the frequency of amide I band and the content of β-sheet between high pressure-induced and heat-induced surimi gels of large yellow croaker. However, high pressure significantly increased the α-helix content and decreased the content of random-coil and β-turns of the surimi gels (P<0.05). In addition, changes in the tertiary structures were observed between the pressure-induced and heated-induced surimi. The normalized intensity of the Raman band near 760 cm?1 in pressure-induced surimi gels of large yellow croaker was stronger than that of heat-induced gels. This means that the level of hydrophobic microenvironment exposure to the polar aqueous solvent is lower in pressure-induced surimi gels. These changes had significant correlations with the changes of texture properties and water holding capacity. The mobility of bound water was positively related to the springiness and cohesiveness of surimi gels. The content of movable water was negatively associated with cohesiveness. Consistently, the content of bound water and the mobility of movable water were in parallel with water holding capacity. Furthermore, the contents of α-helix and β-sheet were positively correlated with cohesiveness and water holding capacity, but negatively correlated with gumminess, chewiness and hardness. Collectively, high pressure altered the protein structure in flesh of large yellow croaker, resulting in the changes of surimi moisture status and texture quality. This study provides a theoretical reference for the application of Low-field NMR and Raman spectroscopic technique to evaluate and enhance the quality of surimi products.
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2015年第23期246-252,共7页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金(31271890)
浙江省教育厅中青年学科带头人学术攀登项目(pd2013100)
宁波农业重大择优委托项目(2012C10024)
关键词
凝胶
核磁共振
光谱分析
大黄鱼
鱼糜
超高压
gel
nuclear magnetic resonance
spectrum analysis
large yellow croaker
surimi
ultra-high pressure
