Orthogonal array design for optimization of phenyllactic acid–sodium alginate blend coating and its effect on the browning and quality of minimally processed lily bulbs

BACKGROUND: In order to develop active packaging of lily products, we for the first time investigated the effects of phenyllactic acid (PLA) incorporated into a sodium alginate (SA)-based coating on the quality of minimally processed lily bulbs stored at 4 °C for 15 days. It was noticed that a PLA-SA blend coating treatment could inhibit browning and maintain the firmness and ascorbic acid of minimally processed lily bulbs. Compared with the control, polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia-lyase (PAL) activities of PLA-SA blend coating treated minimally processed lily bulbs reduced by about 31%, 21% and 29% on the 15th day, respectively. Total phenolic and quinone contents decreased, respectively, by 16% and 55% at the same time. Moreover, PLA-SA blend coating treatment eliminated the accumulation of malonaldehyde (MDA) while inhibiting microbial growth of minimally processed lily bulbs. CONCLUSIONS: These results showed PLA-SA blend coating could effectively maintain quality of minimally processed lily bulbs stored at 4 °C, and it might be a prospective technology.