超高压处理对鲜切莴苣酶促褐变及相关基因表达的影响

Effects of high pressure process treatment on enzymatic browning and related gene expression of fresh-cut lettuce

鲜切莴苣在贮藏销售过程中极易褐变,严重影响鲜切莴苣的商品价值。为探究超高压(high pressure process,HPP)处理对鲜切莴苣褐变的影响,以鲜切莴苣为原料,采用不同压力(100、200、400 MPa)处理鲜切莴苣,置于4℃贮藏8 d,测定其在贮藏过程中色泽、褐变指数、失重率、硬度、总酚含量、类黄酮含量、丙二醛(malonaldehyde,MDA)含量、多酚氧化酶(polyphenol oxidase,PPO)活力、过氧化物酶(peroxidase,POD)活力和苯丙氨酸解氨酶(phenylalnine ammonia lyase,PAL)活力等相关指标。结果表明,与对照组相比,HPP处理可有效延缓鲜切莴苣的褐变,其压力越大,抑制的效果越显著。其中400 MPa处理延缓鲜切莴苣褐变的效果最好,能够显著抑制鲜切莴苣的总酚和类黄酮含量的上升,并有效抑制贮藏过程中PPO、POD和PAL的活力及相关基因表达。综上所述,HPP处理可以较好地保持鲜切莴苣贮藏过程中的色泽,有效延长贮藏保鲜期。

Fresh-cut lettuce is vulnerable to browning during storage and distribution,seriously affecting its commodity value.Effect of high pressure processing(HPP)treatment on enzymatic browning of fresh-cut lettuce was explored after treating with different pressure conditions(100,200,and 400 MPa)and then storing at 4℃for 8 d.The changes of color,browning index,weight loss rate,hardness,total phenolic content,flavonoid content,malondialdehyde(MDA)content,polyphenol oxidase(PPO)activity,peroxidase(POD)activity,and phenylalanine ammonia lyase(PAL)activity were measured during storage.Results showed that HPP treatment could effectively delay the browning of fresh-cut lettuce compared with CK group,the treated pressure is higher,and the suppression effect is more significant.400 MPa treatment was the most effective for delaying the development of browning,which significantly inhibited the increase in the contents of total phenolic and flavonoids,and suppressed PPO,POD,PAL activity and the gene expressions levels of LsPPO,LsPOD and LsPAL.Therefore,HPP treatment evidently maintains the better color of fresh-cut lettuce during storage to effectively prolong the storage period.