Abstract Browning is the major issue affecting the quality and shelf-life of fresh-cut potatoes. In this paper, in order to study the influences of maturity on browning and its mechanism, potatoes were harvested at three different stages, and the browning degrees, related physiological and biochemical properties of potatoes were evaluated. The results showed that with the increased maturity, potatoes are more prone to browning. However, polyphenol oxidase (PPO) activities of late harvested potatoes were lower than early and middle harvested ones, and main PPO genes expressed significantly higher in early harvested potatoes than in middle and late harvested ones. Generally, the antioxidant capacity was enhanced with the increase of maturity, which was not in line with more browning of late harvested potato. The content of total free amino acids (FAAs) increased significantly in late harvested potatoes, and adding the differential contents of total FAAs aggravated the mash browning of early harvested potato. Accumulation of each FAA also increased significantly with the development stage from middle to late harvest date. Addition of differential amino acids showed that isoleucine and other eleven amino acids can inhibit the browning of potato mash, but serine, lysine and tyrosine, especially tyrosine, promoted the browning degree significantly. Results demonstrated that harvest maturity affects the browning of fresh-cut potatoes by influencing the accumulation of FAAs especially tyrosine, not by PPO activity and antioxidant capacity. This research comprehensively elucidated why the potatoes with different maturities have different browning degrees.

中文翻译：

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收获成熟度通过影响氨基酸含量影响鲜切马铃薯褐变

摘要 褐变是影响鲜切马铃薯品质和保质期的主要问题。本文为研究成熟度对褐变的影响及其机制，分三个不同阶段收获马铃薯，对马铃薯的褐变程度及相关生理生化特性进行评价。结果表明，随着成熟度的增加，马铃薯更容易发生褐变。然而，晚收马铃薯的多酚氧化酶（PPO）活性低于早收和中收马铃薯，主要PPO基因在早收马铃薯中的表达量显着高于中晚收马铃薯。总体而言，抗氧化能力随着成熟度的增加而增强，这与晚收马铃薯褐变更多的情况不符。晚收马铃薯总游离氨基酸（FAA）含量显着增加，且添加不同含量的总FAA加剧了早收马铃薯的褐变。每个FAA的积累也随着收获期中后期的发展阶段而显着增加。添加差异氨基酸表明，异亮氨酸和其他11种氨基酸均能抑制马铃薯醪褐变，而丝氨酸、赖氨酸和酪氨酸，尤其是酪氨酸对褐变程度有显着促进作用。结果表明，收获成熟度通过影响 FAA 尤其是酪氨酸的积累来影响鲜切马铃薯的褐变，而不是通过 PPO 活性和抗氧化能力。本研究全面阐明了不同成熟度马铃薯褐变程度不同的原因。