坛紫菜多糖对微冻南美白对虾仁肌原纤维蛋白氧化和结构特性的影响

Effects of polysaccharides derived from Porphyra haitanensis on oxidation and structural properties of myofibrillar protein of Litopenaeus vannamei during superchilling storage

该研究通过探讨坛紫菜多糖浸泡的南美白对虾仁在微冻过程中肌原纤维蛋白氧化特性和结构特性的变化规律,从蛋白质角度揭示坛紫菜多糖抗冻保鲜的潜在机制。将虾仁分别用5 mg/mL坛紫菜多糖,蒸馏水(空白对照)和5 mg/mL焦磷酸钠(阳性对照)浸泡处理后于-3℃微冻贮藏,每5 d测定指标。结果表明,与对照组相比,坛紫菜多糖浸泡虾仁可显著延缓总巯基含量下降,防止羰基含量和表面疏水性上升,阻碍平均粒径增加和Zeta电位绝对值的下降(P<0.05),抑制肌原纤维蛋白的氧化和聚集。圆二色光谱分析表明,坛紫菜多糖显著抑制肌原纤维蛋白α-螺旋相对含量的降低(P<0.05)。内源荧光光谱分析表明,坛紫菜多糖能缓解肌原纤维蛋白中发色基团暴露,维持蛋白空间结构稳定性。扫描电镜结果显示,坛紫菜多糖能保持虾肌肉组织微观结构的完整性。该研究为坛紫菜多糖作为新型绿色无磷抗冻保鲜剂添加到水产品冷冻过程中保护蛋白质特性提供理论依据。

Protein oxidation is the main reason for the quality deterioration in shrimp products.To reveal the potential mechanism for the cryoprotective properties of the polysaccharides derived from Porphyra haitanensis(PHP)in terms of protein,this study investigated the changes of oxidation and structural properties of myofibrillar protein from superchilling stored Litopenaeus vannamei soaked with PHP.The shrimps were soaked with 5 mg/mL PHP,distilled water(blank control)or 5 mg/mL sodium pyrophosphate(positive control),respectively,and then measured indicators every 5 days after being stored at-3℃.Results showed that compared with the control groups,the decrease of sulfhydryl content and absolute value of Zeta potential were significantly delayed,and the increase of carbonyl content,surface hydrophobicity,and average particle size was dramatically inhibited for the PHP group(P<0.05).It indicated that PHP could hinder the oxidation and aggregation of myofibrillar protein.Circular dichroism spectra demonstrated that PHP significantly prevented the decline of theα-helix relative content of myofibrillar protein(P<0.05).Fluorescence spectra suggested the exposure of tryptophan residues was alleviated by PHP and maintained the stability of the three-dimensional structure of the myofibrillar protein.Scanning electron microscopy results displayed that PHP could keep the integrity of the microstructure of muscle tissue.This study provides a theoretical basis for PHP to be used as a new green phosphate-free cryoprotectant to protect protein properties in aquatic products during freezing.