基于Pickering foams的玉米酸面团膨胀性能改良机制研究

Maize is the globally largest cereal, developing gluten-free maize food has become the areas of research focus. It has been recognized that sourdough play an important role in improving the texture of fermented flour products. The research showed that, Pickering foams of fermented dough is one of important factors for improving the expansion properties of dough and product. Early studies have shown that Pickering foams could be observed in fermented maize sourdough. Nevertheless, the questions of how it could happen and how it affects the texture of maize dough are unclear. Therefore, the following work need to be done: ① expliciting the material basis (constitute, properties, structure) and condition (process stage and fermentation condition) of Pickering foams from maize sourdough; ② illuminating the effect of maize sourdough on the Pickering foams stability, microstructure, and interfacial characteristics based on water/paraffin system; ③ exploring the interaction of Pickering foams on the bubble dynamics behavior and expansion properties especially gas cell structure of maize dough. ④ By studying the relationship of the material basis, Pickering foams and expansion properties of maize sourdough, the mechanism of texture improvement of maize sourdough based on Pickering foams formed may be clarified. The results may be expected to provide new ideas to mechanism of quality improvement of fermented gluten-free dough and provide theoretical support for the quality regulation of maize staple processing.

玉米是全球第一大谷物，无麸质玉米食品的研究开发已成为当前研究的热点。酸面团技术是改善无麸质发酵面制品质构特性的有效手段，研究显示Pickering foams(PF)是改善发酵面团膨胀性能重要的因素之一。本团队在玉米酸面团发酵过程中观察到PF的形成，但PF的产生条件及对面团膨胀性能的改良机制均不明确。项目拟通过：①明确玉米酸面团形成PF的物质基础（组成、性质、结构）和形成条件（加工阶段、发酵条件）；②阐明水蜡模型体系下不同酸面团的PF稳定性、微观结构、界面作用等的特征变化；③探析PF如何影响玉米面团/面制品气泡动力学行为、气室结构等膨胀性能与质构特性。④基于玉米酸面团“PF物质基础-PF特性-膨胀性能”三者内在的关联分析，揭示玉米酸面团PF对面团膨胀性能的改良机制。项目实施有望为无麸质酸面团发酵食品质构改良机制提供新的研究思路，为玉米主食加工的品质调控提供科学依据。

无麸质食品是解决麸质过敏人群饮食的重要策略，提高面糊/面团的膨胀性能及加工稳定性是改善无麸质制品品质的重要方式之一。研究前期观察到乳酸菌发酵的玉米面团中可能存在pickering乳化作用，并影响产品的膨胀稳定性能，但具体机制不清。由此，本研究基于玉米无麸质发糕及水/液体石蜡乳液模型，探讨乳酸菌处理玉米粉-pickering乳化稳定性-制品膨胀性能三者的内在关联。（1）基于代谢速率及品质性状筛选适宜的发酵菌种及条件，采用鼠李糖乳杆菌，在37℃发酵48 h玉米粉具有明显的pickering 乳化作用；（2）乳酸菌预处理可使玉米粉吸水膨胀后粒径下降30%，表面电荷数降低，zeta电位绝对值从21mv下降至12mv，表面疏水性增加；研究认为这与乳酸菌发酵导致玉米粉损伤淀粉含量下降，颗粒表面疏水性蛋白暴露有关；（3）乳酸菌预处理玉米粉可显著提高水/液体石蜡乳液体系的放置稳定性，并在加热后直接形成糊化壳层结构，不易发生塌陷或气体泄漏；（4）处理组玉米面团在发酵流变实验中出现孔洞的时间推迟至第54 min，气体泄露总体积减少为31 mL，气体保留系数提高到98.9%；制品比容及气孔大小均与pickering乳液粒径呈正相关。综上所述，乳酸菌发酵改变了玉米粉的组分及分布特征等，改善了粉体润湿性、粒径、电位等特征，使其易于吸附在两相界面上，形成较稳定的pickering乳液/泡沫体系。在面糊制作过程中同样吸附在两相界面上，并通过形成更加稳定的大气孔提高制品的膨胀性能。根据任务书要求，本项目发表论文2篇，申请专利3项，授权2项，基本完成任务。