小分子醇控制生鲜面贮藏过程中面筋蛋白崩解的机制研究

Fresh noodles are the traditional staple food in China. These products are generally high in water content, which accelerate the physiological and biochemical reactions, thus leading to the deterioration. This has become a critical problem in the industrial production. Our previous studies found that the textural deterioration induced by the collapse of gluten network was another leading factor of fresh noodle deterioration, in addition to the spoilage caused by microbial growth. Small amounts of low molecular polyols showed no inhibiting effect on microbial growth but can significantly inhibit the collapse of gluten network and deterioration of texture. However, the mechanisms are still unknown. Based on these results, a systematic study is further conducted on the effect of low molecular polyols on the macroscopic quality and microscopic characteristics of gluten network. DSC, NMR, MRI are used to analyze water status and its influence on gluten structure; meanwhile, based on the polymer physics theory, TGA, AFM, etc. are used to investigate the changes in gluten protein molecular rigidity as affected by low molecular polyols. Then, by tracing the polymerization and depolymerization of gluten, conformation changes, chemical bond changes, and the dynamics of gluten distribution during storage, underlying interactions in polyols-gluten system are revealed. Based on these studies, the inhibiting mechanisms of low molecular polyols on the collapse of gluten network are proposed to provide theoretical and experimental foundation for the regulation of the storage stability of fresh noodles.

我国传统的生鲜面制品因含水量高，内部生理生化反应迅速而极易变质，这成为困扰生产者的一个技术难题。前期研究发现生鲜面贮藏过程中除微生物生长引起的霉变外，还存在面筋蛋白网络结构崩解而导致的质构品质迅速劣变；少量添加小分子醇虽不能抑制微生物生长，却能明显抑制这一劣变作用的发生，该现象产生的原因和抑制机理目前尚不清楚。本项目在此基础上，系统研究生鲜面加工贮藏过程中小分子醇对面筋蛋白宏观品质和微观特征的影响规律；并采用DSC、NMR、MRI等技术分析面筋水合状态与迁移特性对其结构变化的影响；同时借鉴高分子物理理论，采用TGA、AFM等技术探究小分子醇干预下面筋蛋白分子链刚性的变化；通过跟踪面筋蛋白及其亚组分的解聚和重聚行为、构象改变、化学键变化以及面筋相的动态分布，探究体系的内在交互作用；从多角度解析小分子醇对生鲜面中面筋网络崩解和质构劣变的抑制作用及机制；为生鲜面贮藏品质的调控提供理论和试验依据。

我国传统的生鲜面制品因含水量高、水分活度大，内部生理生化反应迅速而极易引发变质，这成为困扰生产者的一个技术难题，也是制约该类制品工业化生产的瓶颈问题。本项目在前期研究的基础上，进一步探明了生鲜面制品品质劣变的具体机制和内在规律，并对三种不同来源、结构及-OH数目的小分子醇（甘油、丙二醇、山梨醇）对生鲜面贮藏过程中面筋蛋白网络崩解及质构品质劣变的抑制作用及机制进行了深入探究。研究发现生鲜面贮藏过程中蛋白质组分解聚，面筋纤维断裂引起网络结构崩解；随贮藏时间的延长，等温吸湿曲线下移，水分子核磁共振横向弛豫时间T2增大，弛豫峰右移；MRI图像显示，生鲜面内部组织结构被破坏，水分分布不均且向表面迁移。少量添加小分子醇虽不能抑制微生物生长，却能明显抑制贮藏过程中面筋蛋白的崩解及煮后质构品质劣变。宏观层面，适量小分子醇能改善面团流变学特性，抑制贮藏过程中乳酸溶剂保持能力（LA-SRC）、谷蛋白大聚体（GMP）湿重及煮后硬度、弹性和咀嚼性的下降。结构层面，添加小分子醇显著抑制贮藏过程中生鲜面中面筋纤维的断裂及可冻结水含量的增加，抑制生鲜面内部组织结构的破坏和水分的迁移。分子层面，小分子醇能增强面筋蛋白分子间氢键相互作用，使构象更稳定；分子排阻色谱（SE-HPLC）和原子力显微镜（AFM）结果显示，小分子醇能促进生鲜面加工过程中面筋蛋白解聚和重聚的动态变化，使蒸煮过程中分子链聚集程度更高。本研究从多角度解析了小分子醇对生鲜面中面筋网络崩解和质构劣变的抑制作用及机制，为生鲜面贮藏品质的调控提供了指导。在此基础上，初步探究了微波处理诱导生鲜面中面筋蛋白聚合改性和对生鲜面贮藏稳定性的影响，发现微波处理可以显著抑制小麦粉中的微生物数量和多酚氧化酶（PPO）活性，延长生鲜面货架期；同时可诱导面筋蛋白组分适度聚合，显著改善面团流变学特性，维持生鲜面质构品质的稳定性；这一结果为生鲜面的综合保鲜提供了新思路。