BACKGOUND Kiwifruit (Actinidia) has long been called the 'king of fruits' because of its unique flavor and the wide range of bioactive compounds which contains ascorbic acid, phenolics and minerals. These bioactivities are influenced by species and cultivars. However, to date few studies are concerned about the effect of ripening time on fruit quality. Here, early and late ripening kiwifruits were investigated to determine their contents of ascorbic acid, organic acid, and phenolic compounds. RESULTS: The results indicated that early ripening cultivars contained higher quinic acid and malic acid, while citric acid were found in large amounts in late ripening kiwifruits. Most of the early ripening cultivars contained higher free phenolic fractions than the late ripening fruits, mainly due to the high levels of epicatechin. However, conjugated phenolics, mainly including caffeic and 2,3,4-trihydroxybenzoic acid, achieved the higher levels in the late ripening cultivars. Free phenolics were higher than conjugated phenolics in the early ripening cultivars. Principal component analysis revealed some key compounds that differentiated the kiwifruits, and all the kiwifruits were divided into two subgroups as early and late ripening cultivars. CONCLUSION: Ripening time had a great impact on the accumulation of bioactive compounds. The early ripening cultivars, compared to the late ripening ones, was characterized by higher levels of free neochlorogenic acid and epicatechin, while the late ripening kiwifruits, contained higher amounts of conjugated phenolics. Results from this study provide further insights into the health-promoting phenolic compounds in kiwifruit, and also provide good evidence to aid consumer selection. This article is protected by copyright. All rights reserved.

中文翻译：

---

早熟和晚熟猕猴桃品种中游离、结合和结合酚类物质的表征

背景猕猴桃（猕猴桃）因其独特的风味和广泛的生物活性化合物而被称为“水果之王”，其中含有抗坏血酸、酚类物质和矿物质。这些生物活性受物种和栽培品种的影响。然而，迄今为止，很少有研究关注成熟时间对果实品质的影响。在这里，研究了早熟和晚熟的猕猴桃，以确定它们的抗坏血酸、有机酸和酚类化合物的含量。结果：结果表明，早熟品种奎宁酸和苹果酸含量较高，而晚熟猕猴桃含有大量柠檬酸。大多数早熟品种的游离酚含量高于晚熟果实，这主要是由于表儿茶素含量高。然而，共轭酚类物质，主要包括咖啡酸和 2,3,4-三羟基苯甲酸，在晚熟品种中达到较高水平。在早熟品种中游离酚高于共轭酚。主成分分析揭示了一些区分猕猴桃的关键化合物，将所有猕猴桃分为早熟和晚熟品种两个亚组。结论：成熟时间对生物活性化合物的积累有很大影响。与晚熟品种相比，早熟品种的特点是游离新绿原酸和表儿茶素含量更高，而晚熟的猕猴桃则含有更多的共轭酚类物质。这项研究的结果为猕猴桃中促进健康的酚类化合物提供了进一步的见解，并提供良好的证据来帮助消费者选择。本文受版权保护。版权所有。