Engineering Research Center of Bio-process, Ministry of Education/Key Laboratory for Agricultural Products Processing of Anhui Province/School of Food and Biological Engineering, Hefei University of Technology, Hefei 230601, China.
Construction Corps Key Laboratory of Deep Processing on Featured Agricultural Products in South Xinjiang, Tarim University, Alar 843300, China.
Food Res Int. 2024 Apr;182:114141. doi: 10.1016/j.foodres.2024.114141. Epub 2024 Feb 18.
Walnut kernels are prone to oxidation and rancidity due to their rich lipid composition, but the existing evaluation indicators are not sensitive enough to promote their industrial development. This study aims to investigate the potential markers in oxidative rancidity walnut kernels using lipidomics and volatolomics. The results showed that the antioxidant capacity of walnut kernels significantly decreased after oxidation, with the decreasing of total phenolic content from 36276.34 mg GAE/kg to 31281.53 mg GAE/kg, the DPPH and ABTS free radical scavenging activity from 89.25% to 73.54%, and 61.69% to 43.73%, respectively. The activities of lipoxygenase (LOX) and lipase (LPS) increased by 6.08-fold and 0.33-fold, respectively. By combining volatolomics and chemometrics methods, it was found that significant differences existed in the content of hexanal, caproic acid, 1-pentanol, (E)-2-octenal, and 2-heptanenal before and after walnut kernel oxidation (VIP > 1). Based on the results of lipidomics, it can be concluded that the above five compounds can serve as characteristic markers for walnut kernel oxidative rancidity, mainly produced through glycerol phospholipid (GPL), glyceride, linoleic acid (LA), and α-linolenic acid (ALA) metabolism pathways. Possible mechanisms of lipid degradation in oxidized walnut kernels were also proposed, providing technical support for the storage, preservation, and high-value utilization of walnut kernels.
由于含有丰富的脂质成分，核桃仁容易发生氧化和酸败，但现有的评价指标不够敏感，无法促进其产业化发展。本研究旨在利用脂质组学和挥发物组学研究氧化酸败核桃仁中的潜在标志物。结果表明，核桃仁在氧化后抗氧化能力显著下降，总酚含量从 36276.34 mg GAE/kg 降至 31281.53 mg GAE/kg，DPPH 和 ABTS 自由基清除活性分别从 89.25%降至 73.54%和从 61.69%降至 43.73%。脂氧合酶（LOX）和脂肪酶（LPS）的活性分别增加了 6.08 倍和 0.33 倍。通过结合挥发物组学和化学计量学方法，发现核桃氧化前后的己醛、己酸、1-戊醇、（E）-2-辛烯醛和 2-庚烯醛的含量存在显著差异（VIP>1）。基于脂质组学的结果，可以得出结论，上述五种化合物可以作为核桃氧化酸败的特征标志物，主要通过甘油磷脂（GPL）、甘油酯、亚油酸（LA）和α-亚麻酸（ALA）代谢途径产生。还提出了氧化核桃仁中脂质降解的可能机制，为核桃仁的贮藏、保鲜和高值化利用提供了技术支持。
