TG酶诱导下花生蛋白在高水分挤压过程中纤维结构形成机制

During the high-moisture extrusion process, the protein was unfolded, associated, aggregated, and cross-linked, thus forming the meat-like fibrous structure like the animal meat. At present, the fibrous structure of the high-moisture extruded texturized peanut protein can’t be comparable with the rich fibrous structure offered by real animal meat products. In this project, the original conformation of peanut protein was changed by TG enzyme induction method, and the peanut protein with different aggregation degree was extruded under high moisture condition. The extrusion operation was intentionally shut down after reaching steady state (dead-stop). Then, the barrel should be cooled and opened immediately. Samples along the extruder are collected for further analysis. The relationship between the fibrous structure properties of the high-moisture extruded texturized peanut protein and the protein aggregation degree will be analyzed; the six representative extrusion zones will be observed from a multi-scale method from 2D and 3D perspectives; the changes in protein conformation such as protein-protein interactions, in the molecular weight distribution, and in the secondary structure during the high-moisture extrusion process will be examined; the phase behavior of peanut protein including thermal transition properties, thermal decomposition properties, and rheological properties will be revealed; and the mathematical model for the stepwise variation of peanut protein conformation will be built by layered augmented principal component analysis. Above all, the mechanism of the process for forming a fibrous structure of peanut protein with different aggregation degree can be clarified according to the conclusions of this project. Moreover, the study will also identify the key extrusion zones and protein critical structures (domains), which can significantly impact on the fibrous structure. This project will be helpful for controlling the high-moisture extrusion process and improving the fibrous structure quality. It will also provide the scientific basis for developing peanut protein-based meat analogues and uncovering the high-moisture extrusion process systematically, which has been as a “black box”.

花生蛋白高水分挤压过程的本质是蛋白分子的聚集过程，从而形成具有类似动物肉的纤维结构。目前制备的高水分花生拉丝蛋白的纤维结构与动物肉纤维结构仍有差距，无法满足消费者的需求。本项目拟通过TG酶诱导的方式，改变花生蛋白原始构象，对不同聚集程度的花生蛋白在高水分条件下挤压，分析花生蛋白原始构象对纤维结构形成的影响作用；采用“突然停机”方法，取得六个挤压区段中的花生蛋白样品，阐明基于挤压过程相行为变化的高水分花生拉丝纤维结构品质提升机制；揭示不同聚集程度花生蛋白在高水分挤压过程中分子构象多尺度变化机理；建立高水分挤压过程中花生蛋白构象梯次变化与纤维结构形成的关联机制；最终明确高水分挤压过程中促进纤维结构形成的关键挤压区段及蛋白关键结构（域）。研究有助于有效控制和改善高水分花生拉丝蛋白纤维结构的形成过程，为模拟肉产品研发提供科学依据，也为揭开挤压过程“黑箱”效应奠定理论基础。

花生蛋白高水分挤压过程的本质是蛋白分子的聚集过程，从而形成具有类似动物肉的纤维结构。目前制备的高水分花生拉丝蛋白的纤维结构与动物肉纤维结构仍有差距，无法满足消费者的需求。本项目以低温脱脂花生蛋白粉为原料，经过TG酶诱导和高水分挤压，采用“突然停机”的方法，研究了TG酶诱导花生蛋白高水分挤压过程中构象变化与纤维结构形成机制，结果表明，在高水分挤压过程中，TG酶促进了蛋白分子交联，增强了蛋白-脂质相互作用，而蛋白与水的结合能力变差。进一步揭示了蛋白质纤维化网络结构关键结构域的形成机理，明确蛋白质分子在模口区伸展，在模口区和成型区的连接部分，蛋白质类似石墨的“分层叠变”现象是纤维结构形成的关键。将高水分挤压过程中的数据分为设备操作参数即原料和工艺参数、系统响应参数、结构梯次变化参数和产品品质参数四大类，共搜集到花生蛋白高水分挤压过程数据75套（8000余条），构建了高水分花生拉丝蛋白品质形成过程数学模型，为高水分挤压技术可视化平台建设奠定基础，对植物蛋白高水分纤维结构形成机理及酶法改性调控机制进行了深刻解析。与本项目相关研究结果在中科院1区期刊Food Hydrocolloid（IF=11.504）、Food Chemistry（IF=9.231）上高质量SCI论文4篇，在JCR Q1期刊Foods（IF=5.561）、Journal of Integrative Agriculture（IF=4.384）发表SCI文章2篇，另发表EI收录论文2篇（中国食品学报）；申请发明专利6件，授权发明专利2项（含国际专利1项）、实用新型专利3件；获得软件著作权1项；参加国际会议交流4次并做报告，分别与美国塔夫茨大学David Kaplan终身荣誉教授、荷兰瓦赫宁根大学Atze Jan van der Goot教授和澳大利亚皇家墨尔本大学Charles Brennan教授等领域内知名专家开展了线上学术交流活动，联合发表学术论文2篇，培养硕、博士研究生各1名，高标准完成了项目任务和考核指标。