文献类型：期刊文献

英文题名：Identification of Key Antioxidants of Free, Esterified, and Bound Phenolics in Walnut Kernel and Skin

作者：Wu, Shutian[1,2] Mo, Runhong[1] Wang, Ruohui[1] Li, Qingyang[1] Shen, Danyu[1] Liu, Yihua[1]

第一作者：Wu, Shutian

通信作者：Liu, YH[1]

机构：[1]Chinese Acad Forestry, Res Inst Subtrop Forestry, Fuyang 311400, Peoples R China;[2]Shanghai Jingan Dist Environm Monitoring Stn, Shanghai 200072, Peoples R China

年份：2023

卷号：12

期号：4

外文期刊名：FOODS

收录：;Scopus(收录号：2-s2.0-85148899204);WOS:【SCI-EXPANDED(收录号:WOS:000939144600001)】；

基金：This study was supported by the Fundamental Research Funds of CAF (CAFYBB2019QD002 and CAFYBB2017QC002).

语种：英文

外文关键词：walnut kernel; phenolic form; key antioxidant; contribution rate

摘要：Walnut is a natural source of antioxidants. Its antioxidant capacity is determined by the distribution and composition of phenolics. The key phenolic antioxidants in various forms (free, esterified, and bound) in walnut kernel (particularly seed skin) are unknown. The phenolic compounds in twelve walnut cultivars were analyzed using ultra-performance liquid chromatography coupled with a triple quadrupole mass spectrometer in this study. A boosted regression tree analysis was used to identify the key antioxidants. Ellagic acid, gallic acid, catechin, ferulic acid, and epicatechin were abundant in the kernel and skin. The majority of phenolic acids were widely distributed in the free, esterified, and bound forms in the kernel but more concentrated in bound phenolics in the skin. The total phenolic levels of the three forms were positively correlated with antioxidant activities (R = 0.76-0.94, p < 0.05). Ellagic acid was the most important antioxidant in the kernel, accounting for more than 20%, 40%, and 15% of antioxidants, respectively. Caffeic acid was responsible for up to 25% of free phenolics and 40% of esterified phenolics in the skin. The differences in the antioxidant activity between the cultivars were explained by the total phenolics and key antioxidants. The identification of key antioxidants is critical for new walnut industrial applications and functional food design in food chemistry.