ABSTRACT In the present study, the nutritional and phenolic composition as well as the antioxidant activity of sweet potato leaves (SPL) harvested in 3 different periods were determined and compared. Furthermore, gray relational analysis was used to compare the comprehensive nutritional value. Results showed SPL HP1 had the highest protein value (30.8 ± 0.4 g/100 g dw), while SPL HP3 had the highest content of vitamin C (104.6 ± 4.9 mg/100 g dw), vitamin E (5.8 ± 0.4 mg/100 g dw), total polyphenol content (9.1 ± 0.3 g/100 g dw), antioxidant activity (DPPH: 7.4 ± 0.1 g VcE/100 g dw; ABTS: 10.6 ± 0.7 g VcE/100 g dw; FRAP: 0.617 ± 0.005 µmol TroloxE/100 g dw), and comprehensive nutritional value (weighted gray relational grade 0.8336). The individual phenolic composition showed the presence of six caffeoylquinic acids, caffeic acid, and two flavonoids (quercetin and isoquercetin), which were significantly different among different harvest periods. In conclusion, HP3 was an optimal period for harvesting SPL.

中文翻译：

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收获期对甘薯叶的抗氧化活性、营养成分和酚类成分的影响

摘要 在本研究中，测定并比较了 3 个不同时期收获的甘薯叶 (SPL) 的营养成分和酚类成分以及抗氧化活性。此外，采用灰色关联分析来比较综合营养价值。结果显示 SPL HP1 的蛋白质值最高 (30.8 ± 0.4 g/100 g dw)，而 SPL HP3 的维生素 C (104.6 ± 4.9 mg/100 g dw)、维生素 E (5.8 ± 0.4 mg/100 g dw）、总多酚含量（9.1 ± 0.3 g/100 g dw）、抗氧化活性（DPPH：7.4 ± 0.1 g VcE/100 g dw；ABTS：10.6 ± 0.7 g VcE/100 g dw；FRAP：0.6005 ± 0.6107 ± µmol TroloxE/100 g dw）和综合营养价值（加权灰色相关等级 0.8336）。单个酚类成分显示存在六种咖啡酰奎宁酸、咖啡酸、以及两种黄酮类化合物（槲皮素和异槲皮素），不同采收期差异显着。总之，HP3 是收获 SPL 的最佳时期。