Cui Maokai, Mo Runhong, Li Qingyang, Wang Ruohui, Shen Danyu, Tang Fubin, Liu Yihua
Research Institute of Subtropical Forestry, Chinese Academy of Forestry, Fuyang 311400, PR China.
Weinan City Forestry Workstation, Weinan 714000, PR China.
Food Chem X. 2024 Aug 30;23:101792. doi: 10.1016/j.fochx.2024.101792. eCollection 2024 Oct 30.
The phenolic profiles and antioxidant activities during walnut maturation are not well understood. This study used UPLC-MS/MS to evaluate phenolic content in walnuts, including free, esterified, and bound forms, at different maturation stages. Findings showed that free phenolics were predominant, comprising 44.57 % in kernels and 56.54 % in pellicles. In vitro assays showed antioxidant capacity decreased with maturation, with IC values of 0.87-84.43 μg/mL in pellicles and 48.51-712.30 μg/mL in kernels. Most monomeric phenols decreased in concentration as the fruit ripened. OPLS-DA identified 5 and 8 maturity-sensitive phenolics (MSPs) in kernels and pellicles, respectively, with fold changes from 2.32 to 1664.72. Pearson correlation analysis showed a significant correlation between MSPs and antioxidant activity ( > 0.75, < 0.05). Bioinformatics analysis elucidated three key metabolic pathways involved in these changes. This research provides insights into walnut phenolic composition, important for optimizing harvest practices and enhancing nutritional value.
核桃成熟过程中的酚类物质概况和抗氧化活性尚未得到充分了解。本研究采用超高效液相色谱-串联质谱法（UPLC-MS/MS）评估不同成熟阶段核桃中酚类物质的含量，包括游离态、酯化态和结合态。研究结果表明，游离酚类物质占主导地位，在核桃仁中占44.57%，在核桃皮中占56.54%。体外试验表明，抗氧化能力随成熟度降低，核桃皮中的IC值为0.87 - 84.43μg/mL，核桃仁中的IC值为48.51 - 712.30μg/mL。随着果实成熟，大多数单体酚的浓度降低。正交偏最小二乘法判别分析（OPLS-DA）分别在核桃仁和核桃皮中鉴定出5种和8种成熟度敏感酚类物质（MSPs），倍数变化范围为2.32至1664.72。Pearson相关性分析表明，MSPs与抗氧化活性之间存在显著相关性（>0.75，<0.05）。生物信息学分析阐明了参与这些变化的三个关键代谢途径。本研究为核桃酚类成分提供了见解，这对于优化收获实践和提高营养价值具有重要意义。
