淀粉PLs对稻米陈化的作用机制

Rice aging which involves many interactions between components, often result in great reduction of qualities, whereas the understanding of aging mechanism is still unclear. Phospholipids (PLs) are a major class of rice starch lipids that always combined with starch to form amylose-lipid complex, playing significant roles in formation and maintenance of rice nutrition, eating and processing qualities. On the basis of previous research, this project focuses on the changes of PLs contents during storage, to explore the relations between rice PLs, aging and storage qualities. The content of individual PLs components of paddy, brown and white rice stored in different temperature and relatively humidity will be analyzed to dissect the mechanism of storage conditions affecting rice PLs concentration and distribution. Moreover, the changes of pasting properties, thermal properties and texture properties of stored rice, resulted from rice aging will be analyzed to understand the influences of aging on storage qualities. How rice PLs responsible for rice aging and the mechanism of rice aging will be further discussed, depending on the available changes of aging related physicochemical properties. The knowledge of special roles of rice PLs on rice aging will provide insights into rice preservation, deterioration control and quality assessment.

稻米陈化能导致稻米品质劣变，其过程涉及多种组分的相互作用，机理尚未完全阐明。磷脂（PLs）是稻米淀粉脂类的重要组分之一，通常结合淀粉形成淀粉-脂质复合物，影响稻米食用、加工、贮藏品质的形成与维持。本项目拟在前期稻米品质与遗传研究基础上，从淀粉脂类参与稻米陈化过程的角度，研究PLs与稻米陈化及贮藏品质间的关系。通过分析不同温度、湿度贮藏过程中稻谷、糙米和精米各淀粉PLs组分与含量，探索贮藏稻米PLs的变化规律以及贮藏环境对稻米PLs含量与分布的影响机制。同时，分析贮藏过程中稻米糊化、热学、质构等贮藏品质相关理化特性，进一步探索陈化对贮藏品质的影响机制。结合PLs与陈化贮藏品质的变化特征，揭示稻米PLs与稻米陈化间的潜在关系，进一步探讨脂类对稻米陈化的作用机制，为稻米的仓储保鲜、陈化劣变防控以及品质评价提供理论依据。

稻米陈化能导致稻米品质劣变，其过程涉及淀粉、脂质等多种组分的相互作用，机理尚未完全阐明。磷脂（PLs）是稻米脂类的重要组分之一，通常结合淀粉形成淀粉-脂质复合物，影响稻米食用、加工、储藏品质。本项目从淀粉脂类参与稻米陈化过程的角度，研究PLs与稻米陈化及储藏品质间的关系。研究内容主要包括1）分析不同温度、湿度储藏稻谷和精米淀粉与非淀粉PLs组分与含量的变化，探索储藏环境对陈化稻米PLs含量与分布的影响。2）分析陈化稻米糊化、热学等储藏品质相关理化特性，结合PLs变化特征，揭示PLs对稻米陈化的影响机制。研究结果表明，陈米中淀粉和非淀粉PLs组分分别有12种和8种，其中LPC16:0和LPC18:2是陈化稻米中的最主要淀粉和非淀粉LPLs组分。陈谷的总淀粉LPLs含量约为5373.2 - 8210.3 μg/g，低于陈米（5467.0 - 8509.9 μg/g）；陈谷的总非淀粉LPLs组分含量约为56.5-136.5 μg/g，高于陈米（45.5-121.8 μg/g）。高温（40℃）储藏稻米的淀粉TLPC、TLPE和TLPLs的含量普遍低于中（30℃）、低温（20℃）储藏稻米；高湿（95%）储藏导致稻米淀粉LPC18:2、TLPC、LPE18:2与TLPL等PLs组分含量显著降低；同时造成稻谷和精米的非淀粉LPLs组分含量则均显著降低。精米经高温（40℃）储藏后，其PV、HPV、CPV、BD、CS、PT等糊化特性参数普遍显著高于中（30℃）、低温（20℃）储藏稻米；但不同陈化温度对稻谷的糊化特性参数影响则不显著。稻谷和精米经高湿（95%）储藏陈化后的糊化特性参数均低于低湿（50%）储藏稻米。陈谷与陈米的淀粉LPC14:0与HPV、CPV和CS等显著负相关；LPC16:0、LPE14:0和LPE16:0等与PT显著正相关；LPE16:0、LPE18:0、TLPE等与CPV、SB和CS等显著正相关；LPE14:0与To、Tp、Tc等热学特性参数显著正相关。陈化稻米淀粉LPLs组分与PV无显著相关性，其他淀粉LPLs组分与稻米糊化、热学特性均无显著相关性。尽管非淀粉LPC14:0与CS等呈显著负相关，但其他非淀粉LPLs组分与糊化和热学特性参数无显著相关性。本项目的实施阐明了淀粉和非淀粉磷脂对稻米陈化的影响机制，为稻米的仓储、陈化劣变防控以及品质评价提供良好的理论依据。