曲酸处理对娃娃菜采后褐变的影响

为研究曲酸处理对娃娃菜茎部切口褐变的影响及其机制，本实验用0.05 g/L曲酸和超纯水（对照）分别浸泡娃娃菜茎部切口1 min，再在20 ℃、相对湿度90%的条件下贮藏5 d，每天取样分析其感官品质并测定呼吸强度、乙烯释放速率、总酚含量、类黄酮含量及褐变相关酶活力。结果表明：与对照相比，曲酸处理可以有效保持娃娃菜的感官品质，抑制娃娃菜茎部褐变，降低质量损失率、丙二醛含量，提高类黄酮以及总酚含量；抑制过氧化物酶、多酚氧化酶的活力，第5天时曲酸处理组过氧化物酶、多酚氧化酶活力分别比对照组低29.7%、28.5%；增强苯丙氨酸解氨酶、过氧化氢酶活力，第5天时曲酸处理组苯丙氨酸解氨酶、过氧化氢酶活力比对照组分别高1.0%、12.4%。结论：曲酸处理可以有效抑制娃娃菜茎部切口的褐变，保持娃娃菜商品性和营养品质，延长娃娃菜货架期。

Effect of Kojic Acid Treatment on Postharvest Browning of Baby Cabbages

The effect of 0.05 g/L kojic acid treatment on the browning of the stem cut section of baby cabbages and its mechanism were studied. The stem cut section was dipped in 0.05 g/L kojic acid or ultrapure water as a control for 1 min and stored at 20 ℃ and 90% relative humidity for up to five days. Samples were taken every day to measure the appearance, respiration intensity, ethylene release rate, total phenolic content, flavonoid content and the activity of browning-related enzymes. The results showed that kojic acid treatment could effectively maintain the sensory quality of baby cabbages, inhibit the browning of the stem cut section, reduce the mass loss percentage and the content of malondialdehyde (MDA), and increase the content of flavonoids and total phenols. Moreover, it inhibited the activity of peroxidase (POD) and polyphenol oxidase (PPO) (by 29.7% and 28.5% relative to the untreated control group on day 5, respectively), but enhanced the activity of phenylalanine ammonia lyase (PAL) and catalase (CAT) (by 1.0% and 12.4% in contrast to the control group on day 5, respectively). Consequently, we concluded that kojic acid treatment could effectively inhibit the browning of the stem cut section of baby cabbages, maintaining the commerciality and nutritional quality and extending the shelf life.