Effects of clove essential oil and eugenol on quality and browning control of fresh-cut lettuce

This study confirmed the inhibitory effects of clove essential oil (CEO) and eugenol (EUG) on the browning and relevant enzymes of fresh-cut lettuce, and examined associated mechanisms by inhibition kinetics and computational docking analysis. Fresh-cut lettuce was treated with 0.05% CEO and 0.05% EUG solutions, resulting in inhibition of the deterioration of texture quality and browning of the lettuce surface and interior. Compared with the controls, CEO and EUG significantly inhibited the activities of phenylalanine ammonia lyase (PAL), polyphenol oxidase (PPO), and peroxidase (POD, all p < 0.05). EUG suppressed PAL, PPO, and POD in vitro in a dose-dependent manner, with IC50 values of 5.4 ± 0.9, 29.5 ± 3.5, and 61.9 ± 6.7 mM, respectively. The binding and inhibition effects of EUG on PAL, PPO, and POD, determined by inhibition kinetics and computational docking analysis, established EUG as a competitive inhibitor of these browning-relevant enzymes.