Food Technology Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Nuclear Agriculture and Biotechnology Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
Food Chem. 2015 Apr 15;173:38-44. doi: 10.1016/j.foodchem.2014.09.166. Epub 2014 Oct 7.
Gamma-radiation induced browning inhibition in minimally processed shredded cabbage stored (10 °C) for up to 8 days was investigated. γ-irradiation (2 kGy) resulted in inhibition of browning as a result of down-regulation (1.4-fold) in phenylalanine ammonia lyase (PAL) gene expression and a consequent decrease in phenylalanine ammonia lyase (PAL) activity. Activity of polyphenol oxidase and peroxidase, total and individual phenolic content as well as o-quinone concentration were, however, unaffected. In the non-irradiated samples, PAL activity increased as a consequence of up-regulation of PAL gene expression after 24 and 48 h by 1.2 and 7.7-fold, respectively, during storage that could be linearly correlated with enhanced quinone formation and browning. Browning inhibition in radiation processed shredded cabbage as a result of inhibition of PAL activity was thus clearly demonstrated. The present work provides an insight for the first time on the mechanism of browning inhibition at both biochemical and genetic level.
研究了γ-辐射（2 kGy）对最小加工切碎白菜（10°C）贮藏 8 天内褐变的抑制作用。γ-辐射导致苯丙氨酸解氨酶（PAL）基因表达下调（1.4 倍），从而抑制了褐变，PAL 活性随之降低。多酚氧化酶和过氧化物酶的活性、总酚和单体酚含量以及邻醌浓度不受影响。在未辐照的样品中，PAL 活性在贮藏 24 和 48 小时后分别上调 1.2 和 7.7 倍，这是由于 PAL 基因表达的上调所致，这与醌的形成和褐变的增强呈线性相关。因此，辐射处理切碎白菜中 PAL 活性的抑制导致褐变的明显抑制。本研究首次从生化和遗传水平上深入了解了褐变抑制的机制。
