Abstract Pulsed electric fields (PEF) can be applied to induce accumulation of bioactive compounds in plant tissues to obtain commodities with health-promoting properties. However, causes of this accumulation are not fully understood as it may result from either an improvement in extraction or an activation of stress-related biosynthetic pathways. The objective of this study was to investigate the effects of PEF on the physiological response and elucidating the causes underpinning changes in carrot phenolic contents. Respiration rate, oxidative and pectinolytic enzyme activities, synthesis, and content of phenolic compounds were evaluated in PEF-treated (580 J kg−1) carrots after treatment and through storage (12, 24 and 36 h) at 4 °C. The highest production of CO2 and volatile organic compounds was observed 12 h after PEF treatment whereas the largest increases in total phenolic content (80.2 %), p-OH-benzoic (94.7 %), chlorogenic acid (74.9 %) and ferulic acid (52.2 %) occurred 24 h after treatment. Enhanced in phenylalanine ammonia lyase activity indicated that the increase in phenolic compounds may be mainly due to the triggering of biosynthesis pathways instead of structural modifications of the food matrix. Electropermeabilization also induced considerable changes in pectinolytic enzyme activities (increases in pectinmethylesterase and decreases in polygalacturonase) whereas no clear trends were observed for oxidative enzyme activities (peroxidase and polyphenol oxidase) during storage. These results suggest that volatile compounds generation, changes in respiration rate and the biosynthesis of phenolic compounds are induced by PEF application, as a plant defence response to stress.

中文翻译：

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脉冲电场影响胡萝卜内源性酶活性、呼吸作用和酚类化合物的生物合成

摘要 脉冲电场（PEF）可用于诱导植物组织中生物活性化合物的积累，以获得具有促进健康特性的商品。然而，这种积累的原因尚不完全清楚，因为它可能来自提取的改进或与压力相关的生物合成途径的激活。本研究的目的是研究 PEF 对生理反应的影响，并阐明支持胡萝卜酚类含量变化的原因。对经 PEF 处理的 (580 J kg-1) 胡萝卜在 4 °C 下处理和储存（12、24 和 36 小时）后的呼吸速率、氧化和果胶分解酶活性、合成和酚类化合物含量进行评估。在 PEF 处理后 12 小时观察到二氧化碳和挥发性有机化合物的最高产量，而总酚含量 (80.2 %)、对羟基苯甲酸 (94.7 %)、绿原酸 (74.9 %) 和阿魏酸 (52.2 %) 发生在治疗后 24 小时。苯丙氨酸解氨酶活性的增强表明酚类化合物的增加可能主要是由于生物合成途径的触发而不是食物基质的结构改变。电透化还引起果胶分解酶活性的显着变化（果胶甲酯酶增加和聚半乳糖醛酸酶减少），而在储存期间没有观察到氧化酶活性（过氧化物酶和多酚氧化酶）的明显趋势。这些结果表明挥发性化合物的产生，