白果在干燥过程中银杏酸脱除机理与品质调控

Drying is the important process for ginkgo seeds, and scientific regulation and controlment during the drying process is the crux to ensure the quality of the products. This project is gradually carried out to solve the three key scientific issues of ginkgolic acids removal mechanism and quality optimum control of ginkgo seeds during drying process. Firstly, the ginkgolic acids removal mechanism will be studied by proposing a hypothesis that both ‘thermal degradation’ and ‘migration loss by volatilization’ led to the reduction of the ginkgolic acids content, by revealing the effect of drying factors on the ginkgolic acids and further filtering out the critical factors, and by investigating the change regularity of the two removal ways on different drying conditions, which will provide theoretical references for regulating and controling the ginkgolic acids content. Secondly, the dynamic changes of ginkgolic acids, ginkgolides and moisture of ginkgo seeds under different drying conditions will be investigated to find out the key points and control strategy which minimize the ginkgolic acids content and meanwhile preserve the other quality attributes. Lastly, the relationship between color change kinetics and ginkgolic acids content change kinetics，ginkgolides content change kinetics，moisture content changed kinetics will be established. The quality parameter information will be obtained by monitoring and analyzing the color parameters of ginkgo seeds during drying process. This project will provide scientific basis and technical support for the optimum control the quality of ginkgo seeds during its drying process.

干燥是白果重要的加工方式，对干燥过程中白果品质的科学调控是保证品质的关键。项目以在干燥过程中白果中银杏酸脱毒机理以及品质调控所涉及的三个关键科学问题逐步开展研究。首先，以白果中有毒物质银杏酸在干燥加工中脱毒机理为研究内容，提出银杏酸由“热降解”和“迁移挥发”两种方式共同导致白果中银杏酸含量降低，逐步深入研究影响白果中银杏酚酸含量变化的关键因素，以及不同干燥条件下两种脱除方式的变化规律，为银杏酸脱除和含量调控提供理论依据。其次，研究白果在干燥过程中银杏酸、银杏内酯和含水率随时间的动态变化过程，得到最大限度的降低银杏酸含量同时保持其他品质参数品质的关键控制点，寻求最优的调控策略；最后建立白果色泽变化动力学与银杏酚酸、银杏内酯以及含水率动力学的相关关系，通过对色泽的监测和分析，及时获取白果在干燥过程中品质的动态变化信息。项目的实施为白果在干燥加工过程中品质调控提供科学依据和技术支持。

为探究白果在干燥加工中银杏酸脱除机理，降低银杏酸含量，提高食用安全性、提升加工品质。以中短波红外为干燥方式，研究白果在干燥过程中的银杏酸含量和银杏内酯含量在干燥过程中的动态变化规律，建立银杏酸和银杏内酯的动力学模型，并通过阿伦尼乌斯方程从降解能耗的角度阐述银杏酸和银杏内脂的降解机理；根据白果中银杏酸分布、热稳定性和光稳定性等特性，研究多种处理方式对白果干燥特性以及银杏酸含量的影响，阐明银杏酸脱除的相关机制；研究白果的干燥特性及色泽变化动力学，分析了白果的复水率、总黄酮、抗氧化性以及淀粉微观结构等相关品质参数；建立以白果色泽参数为因变量的银杏酸和银杏内酯含量预测模型。此外，研究中发现白果在干燥过程中会发生严重结壳现象，利用体视显微镜并联合扫描电子显微镜观察白果在干燥过程中的结壳过程，并阐述了其结壳控制机理。研究结果表明：白果中总银杏酸和银杏内酯降解的动力学分别适合0阶模型和1阶模型；通过阿伦尼乌斯方程计算得到银杏酸和银杏内酯降解活化能分别为72.10和58.16 kJ/mol，从能量角度印证了银杏酸相比内酯更易发生降解的实验结论；采用去芯、切分以及紫外照射等处理方式可有效降低银杏酸含量，使白果中总银杏酸含量降低至安全水平；建立的多层向前型的人工神经网络模型，能够很好的预测白果色泽参数在干燥过程中的变化；建立了以白果色泽参数L*为因变量的银杏酸和银杏内酯含量预测模型，可通过监测白果的色泽参数来预测银杏酸和银杏内酯的含量。本研究有助于推动白果干燥加工中银杏酸含量控制以及品质调控相关技术的研发与积累，提升我国白果加工的技术水平。