Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China; Institute of Pesticide and Environmental Toxicology, Key Laboratory of Biology of Crop Pathogens and Insects of Zhejiang Province, Ministry of Agriculture Key Laboratory of Molecular Biology of Crop Pathogens and Insects, Zhejiang University, Hangzhou, Zhejiang 310058, PR China.
Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China.
Food Chem. 2024 Dec 1;460(Pt 1):140440. doi: 10.1016/j.foodchem.2024.140440. Epub 2024 Jul 15.
There has been limited research on external browning (EB) of walnut. This work discovered 1888 metabolites and 34 anthocyanins in walnut pellicles (WPs) after three drying methods using widely-targeted and anthocyanin-targeted metabolomics. Based on OPLS-DA and correlation analysis, 64 temperature-responsive metabolites (TRMs; 13 anthocyanins and 51 flavonoids) were identified as critical components in relation to EB. Notably, 14 flavonoids exhibited a strong positive correlation (r > 0.9) with the browning index (BI), with upregulation of >60% after browning. Most of the identified anthocyanins were negatively linked with BI because of degradation (>45%), with correlation coefficients ranging from 0.75 to 0.97. Furthermore, anthocyanidin reductase and laccase were the two key enzymes involved in the EB of WPs, with their activities increasing by 10.57-fold and 1.32-fold, respectively, with increasing drying temperature. A metabolic pathway network of the TRM was built to provide insights into the potential mechanisms underlying EB in WPs.
关于核桃的外褐变（EB），相关研究较少。本研究采用广泛靶向和花青素靶向代谢组学，对三种干燥方法后的核桃内果皮（WPs）进行了研究，共发现了 1888 种代谢物和 34 种花青素。基于 OPLS-DA 和相关性分析，鉴定出 64 种温度响应代谢物（TRMs；13 种花青素和 51 种类黄酮）是 EB 的关键组成部分。值得注意的是，14 种类黄酮与褐变指数（BI）呈强烈正相关（r>0.9），褐变后上调超过 60%。由于降解（>45%），大多数鉴定出的花青素与 BI 呈负相关，相关系数范围为 0.75 至 0.97。此外，花青素还原酶和漆酶是参与 WP 外褐变的两个关键酶，其活性分别增加了 10.57 倍和 1.32 倍，干燥温度升高。构建了 TRM 的代谢途径网络，为 WP 外褐变的潜在机制提供了深入了解。
