抗冻蛋白对冻藏小麦面筋蛋白品质劣变的干预及其机制

The composition, structure and properties of wheat gluten is critical to the quality of flour products. Because of the deterioration of gluten protein during frozen storage, the quality of frozen dough and its large-scale application was affected seriously. How to intervene this deterioration has been a research hotspot in this field. This project will take the matter from ice crystals which is an important factor leading to the deterioration of frozen gluten protein. Antifreeze proteins (AFPs) which can directly act on ice crystal is chosen to intervene on the gluten deterioration during frozen storage. The AFPs with different characteristics will be screened and added to wet gluten and dough. Their effects on the composition, structure and properties of wheat gluten, the state of water and ice crystals, and the quality characteristics of the dough at different stages and under different conditions during frozen storage will be researched systematically. These researches will reveal the relationship between ice crystals formation, recrystallization, moisture migration and gluten deterioration, the different changes of molecular weight, subunit composition, macromolecular conformation, aggregation structure and secondary structure of frozen gluten protein with AFPs, and the intervention and mechanism of various AFPs on gluten deterioration during frozen storage. That will be of great significance to elucidate the deterioration mechanism of gluten during frozen storage, improve frozen dough quality, and extend the application of AFPs in frozen food.

小麦面筋蛋白的组成、结构与性质是决定面制品品质的关键。冻藏过程中面筋蛋白的品质劣变严重影响了冷冻面团的品质和大规模应用，如何干预其劣变已成为该领域的研究热点。本项目从冰晶这一导致冻藏面筋蛋白劣变的重要因素入手，选择能够直接作用于冰晶的抗冻蛋白（AFPs）来干预冻藏面筋蛋白的品质劣变。通过筛选不同特性的AFPs添加于湿面筋和面团中，系统研究冻藏不同条件和不同阶段AFPs对面筋蛋白的组成、结构和性质、水分和冰晶存在的状态、面团的品质特性等的影响；揭示冰晶的形成和重结晶、水分的迁移等因素与面筋蛋白品质劣变的关系；揭示AFPs干预下冻藏面筋蛋白的分子量、亚基组成、分子链构象、聚集态结构、二级结构等的不同变化；明确不同特性的AFPs对冻藏面筋蛋白品质劣变的干预作用和作用机制。项目研究对于了解冻藏面筋蛋白品质劣变的机制、提高冷冻面团的品质、开拓AFPs在冷冻食品中的应用具有重要意义。

小麦面筋蛋白的品质劣变是影响冷冻面团品质最主要的因素之一。抗冻蛋白(AFPs)能够直接作用于冰晶，修饰冰晶形态，抑制其重结晶，在冷冻面团领域具有广阔的应用前景。本项目筛选出三文鱼抗冻多肽（SaAFP）、燕麦抗冻蛋白（AsAFPs）及异源表达了重组胡萝卜AFP (rCaAFP)、重组点带石斑鱼AFP (rFiAFP)和重组黄粉虫AFP (rTmAFP)；并将以上AFPs添加到湿面筋和面团中，研究了冻藏不同条件和不同阶段AFPs对面筋蛋白的组成、结构和性质、水分和冰晶存在的状态、面团的品质特性等的影响；明确不同特性的AFPs对冻藏面筋蛋白品质劣变的干预作用和作用机制。结果发现，SaAFP、rCaAFP、rFiAFP和rTmAFP的热滞活性分别为0.53°C、1.62°C、4.23°C和7.57°C；三种重组AFPs（rAFPs）中rTmAFP修饰冰晶形态能力最强，rCaAFP抑制冰晶重结晶的能力最强。SaAFP、AsAFPs、rCaAFP、rFiAFP和rTmAFP均可以减缓冻藏面筋蛋白的品质劣变。在冻融循环和冻藏过程中，SaAFP能减缓面筋蛋白、麦谷蛋白和醇溶蛋白可冻结水含量的增加，减缓弹性模量和粘性模量的降低，保护蛋白的二级结构和微观结构；并且SaAFP能减缓面筋蛋白和麦谷蛋白游离巯基含量的增加和谷蛋白大聚体的解聚。AsAFPs可通过抑制冰晶形成和重结晶，减少冻结及冻藏对面筋网络的破坏，保护面筋蛋白在冻藏过程中免受冰晶形成所造成的机械破坏，从而减缓面筋蛋白和麦谷蛋白的解聚；AsAFPs可降低冻藏面筋蛋白的熔融焓和可冻结水含量，保护其流变学性质和网络结构。rTmAFP和rCaAFP分别在冻结和冻藏阶段对冷冻面团品质的保护效果最佳，这分别与rTmAFP修饰冰晶形态能力强、rCaAFP抑制冰晶重结晶能力强有关。rAFPs对冷冻面筋蛋白品质劣变的干预机制是通过减缓GMP解聚、保护麦谷蛋白粘弹性、减弱冰晶形成和重结晶对麦谷蛋白网络结构及麦谷蛋白、醇溶蛋白二级结构的破坏而抑制面筋蛋白整体品质的劣变。本项目对于系统了解不同特性AFPs在冻藏不同阶段对面筋蛋白品质劣变的干预作用、提高冷冻面团及其烘焙产品品质、开拓AFPs在冷冻食品中的应用具有重要意义。

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