卡拉胶寡糖对冷冻虾仁中冰晶形成及演变的影响机制

Frozen storage is the most common method for the long-term preservation of shrimp products, which play an important role in the frozen seafood industry in China. However, some undesirable changes, such as growth and recrystallization of ice crystals, protein denaturation, decreased water-holding capability, and drip loss in muscle can still occur during the freeze/thaw process, which negatively affect the nutritional quality and texture acceptability of shrimp products. The possible mechanisms of cryoprotective roles of some saccharides have been provided based on previous reports, including the water replacement, water entrapment, and vitrification (glass formation) hypothesis. However, the above studies stay at the hypothesis stage, and some controversies still exist. This study serves to investigate the roles of carrageenan oligosaccharides on cryoprotective mechanisms occurred in frozen peeled shrimp (Litopenaeus vannamei). The cryoprotective effects will be investigated by monitoring the bonding mode between saccharides and ice crystals, changes of ice-crystal microstructure, computational studies of molecular dynamics, low field nuclear magnetic resonance, growth kinetics of ice crystals, etc. The cryoprotective mechanisms of carrageenan oligosaccharides will be further elucidated by the relationships among the formation and growth of ice crystals, the stability and functionality of muscle proteins occurred in shrimp muscle during the frozen storage. This study could prove helpful in understanding the cryoprotective mechanisms of saccharides occurred in frozen shrimp. This application is of utmost interest, and might have widespread applications to extend the commercialization of refrigerated seafood to better guarantee quality and safety.

冷冻虾仁制品在我国冷冻水产行业中占有举足轻重的地位，但随着冻藏时间延长，肌肉中冰晶的形成、长大及重结晶造成组织损伤加剧，致使解冻后肌肉汁液流失增多、质构特性发生劣变。糖类物质作为常用抗冻保护剂，其对冷冻水产品中冰晶的影响作用主要有“水分子取代”、“水分子束缚”和“玻璃化转变”三种解释，但均停留在假说阶段，何种机制发挥主要作用尚存在较多分歧。本项目在前期研究及文献报道基础上，以南美白对虾虾仁为研究对象、卡拉胶寡糖为冰晶控制剂，基于水产品冻藏品质劣变及抑制理论，通过糖分子与冰晶间键合模式、冰晶结构完整性、蛋白质同源模建及分子模拟、低场核磁共振及冰晶生长演变动力学等研究，揭示卡拉胶寡糖处理与冷冻虾仁中冰晶形成及演变、肌肉蛋白质稳定性之间相互关系，阐明卡拉胶寡糖对冷冻虾仁肌肉品质的低温保护机制。研究成果有望补充与完善水产品低温劣变理论，也为冷冻水产品品质保障与冰晶控制提供新的途径和理论基础。

冷冻虾仁制品在我国冷冻水产行业中占有举足轻重的地位，但随着冻藏时间延长，肌肉中冰晶的形成、长大及重结晶造成组织损伤加剧，致使解冻后肌肉汁液流失增多、质构特性发生劣变。本研究以南美白对虾虾仁为对象、卡拉胶寡糖等糖类分子为冰晶控制剂，研究了糖分子对冻结虾仁肌肉品质特性、温度波动下冰晶生长及重结晶、糖分子与冰晶颗粒、肌球蛋白之间的相互关系等，获得研究结果如下：. 1. 卡拉胶寡糖、海藻糖等糖分子预处理，即使在贮藏温度波动条件下，仍可有效抑制冻结虾仁肌肉中冰晶颗粒的直径及形成面积，减弱重结晶效应对肌纤维的物理损伤作用。. 2. 在冰晶生长过程中，糖分子通过氢键驱动靠近并嵌入冰晶界面中，通过与冰晶颗粒结合、破坏生长界面完整，扰乱水分子向冰晶转变过程，并促使冰晶颗粒溶剂化，实现对冰晶颗粒生长及重结晶抑制作用。. 3. 在肌肉组织中，渗入糖分子通过氢键、静电及亲疏水性作用，与虾仁肌球蛋白特定氨基酸结合，取代表面部分水分子，提高肌球蛋白稳定性、降低部分区域柔性，维持肽链正常的空间构象，从而减弱低温胁迫对肌球蛋白的变性作用。. 4. 发表学术论文18篇，其中SCI收录10篇（其中TOP论文5篇）、中文核心8篇，申请国家发明专利2项。培养硕士研究生8名，联合培养博士研究生1名，培养青年教师2名。. 研究成果解释了基于糖分子的冰晶生长抑制和肌球蛋白稳定机制，补充与完善了水产品低温劣变理论，也为冷冻水产品品质保障与冰晶控制提供新的途径和理论基础。

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