基于戊聚糖改性的发酵面团薄层液膜变化及质构改良机制

It has been widely recognized that pentosan and their related enzymes play an important role in improving the texture quality of fermented flour products, and the current study was restricted to their effect on the formation of gluten network structure. The latest research showed that there was a liquid lamellae structure in fermented dough besides gluten network, which was also related with product texture. It has been proved that liquid lamellae was rich in soluble pentosan, nevertheless, the effect of pentosan and related enzymes on the characteristic of liquid lamellae and their related with texture quality improvement are unclear. In this research, polymer physics and interface chemistry methods were used to study the change of composition and structure of main components in liquid lamellae treated by pentosan hydrolase and oxidase alone or combined; the protein adsorption behavior, interfacial rheological properties and interactions between molecular adsorption layer intervened by enzymes related with pentosan; and the change regularity of bubble dynamics behavior and textural variation characteristic especially gas cell structure of enzymatic modification of doughs. By studying the relationship between liquid lamella structure and functionm, the mechanisms of texture improvement of fermented flour products based on pentosan bio-enzyme modification may be clarified. The results may be expected to provide new ideas to quality improvement of traditional fermented flour products of China, and provide theoretical support for the function improvement of multiphase food systems.

戊聚糖及相关酶制剂改良发酵面制品质构的作用已得到公认，但认识多局限于对面筋网络结构的干预。最新研究表明发酵面团体系除面筋网络外还存在薄层液膜结构，对面制品质构亦有显著影响。已知此薄层液膜富含可溶性戊聚糖，但戊聚糖及其相关酶对薄层液膜特性的影响以及是否藉此发挥品质改良作用等相关机制尚不清楚。本项目借鉴高分子物理与界面化学手段，研究戊聚糖在水解酶和氧化酶单独或协同作用下发酵面团薄层液膜主要构成物质（可溶性戊聚糖、蛋白质）组成、结构变化；戊聚糖相关酶干预下的蛋白界面吸附行为、界面扩张流变特性以及吸附层分子作用模式等液膜界面特性的变化；戊聚糖酶改性面团气泡动力学行为、内部气室结构等质构特征变化；通过对戊聚糖相关酶作用下液膜核心物质结构-功能变化规律的研究，揭示基于戊聚糖改性的发酵面制品质构改良机制。研究成果有望为我国传统发酵面制品品质改良提供新思路，并为多相食品体系功能特性改善提供理论支撑。

戊聚糖及相关酶改良发酵面制品质构的作用已得到公认，但主要侧重于其对面筋网络结构的干预。薄层液膜是发酵面团中的重要结构，对决定产品质构的气室结构亦有一定影响。但戊聚糖及其相关酶对该结构的影响以及是否藉此发挥品质改良作用等相关机制尚不清楚。本项目以富含戊聚糖的全麦发酵面团为研究对象，详细研究了戊聚糖酶（Pn）和葡萄糖氧化酶(GOX)对产品品质的影响，探讨了质构特性与面团戊聚糖（AX）、蛋白组成、流变特性、面筋网络结构变化之间的联系。在此基础上，重点研究了酶改性面团水相溶液（DL)AX、蛋白含量和结构及其泡沫特性变化，并从DL界面吸附行为和界面流变学层面揭示了泡沫特性改善的内在机制及其对气室稳定性的贡献。结果表明，Pn和GOX在合适用量下均可显著制品品质，形成多孔的气室结构。Pn促进不可溶AX的溶出，提高面团延展性。GOX提高了谷蛋白大聚体（GMP）的含量，提高面团韧性，形成连续多孔且结构致密的气室结构。通过研究超高速离心法提取的DL间接获得了薄层液膜物质组成和性质的信息。发现Pn和GOX可分别提高DL当中WEAX和蛋白含量，降低面筋网络的持水能力，提高 DL得率。Pn、GOX组与对照组的蛋白表达存在一定差异，但Pn未改变蛋白分子大小质量；而GOX则促进二硫键和蛋白质分子间 β-sheets结构的形成，产生较大的蛋白聚集体并催化形成蛋白-多糖复合物。Pn、GOX均可改善DL中蛋白质的表面疏水性，但由于Pn使DL黏度显著降低，更利于气体渗透和蛋白在气/液界面的吸附，因此对起泡性的改善优于GOX。Pn和GOX均显著的提高了DL泡沫抵抗热应力的稳定性，利于形成更加稳定、细腻的泡沫结构，这与其提高了界面膜抵抗扩张和剪切变形的能力密切相关。在实际发酵面团体系中，薄层液膜强度的提高对于降低面团在发酵和焙烤过程中气泡得聚并和破裂具有积极作用。研究结果为从薄层液膜层面揭示戊聚糖及其相关酶调控发酵面团气室结构形成中的作用的提供了理论依据，为气室结构的面筋网络结构调控理论提供了有利补充。