The effects of ozone treatment on quality and biochemical parameters of fresh-cut lettuce

Although chlorine is the main antimicrobial agent, recently some other sanitizers have been proposed, such as ozone, with positive results. The aim of our study was to investigate the effect of ozone on quality and biochemical parameters of two fresh-cut lettuce types (romaine and iceberg). For the first experiment, the midribs of both types were cut into pieces of 2×2 cm, while for the second one the leaves were cut into horizontal sections of 2 cm. Then, all samples were dipped in water (control) or 1.2 ppm ozonated water for 2 min and packaged in modified atmosphere before storage at 4°C for 6 days. In the first experiment, during storage, the degree of browning in the midribs was evaluated in a scale of 1-5 and the total soluble phenol content (TSPC) and PPO activity were determined. In the second experiment, at the beginning and at the end of storage, TSPC as well as total antioxidant capacity (TAC) were determined. The results of the first experiment showed that the degree of browning of both lettuce types was positive correlated with TSPC, while in romaine lettuce it was also positive correlated with PPO activity. During the storage of control of both types a progressive browning was observed which was highest in romaine lettuce. The ozone treatment didn't affect the degree of browning of both types. The results of the second experiment showed that at the end of storage appreciable changes were observed only in iceberg lettuce. In the control, the TSPC decreased, while the TAC increased. The ozone treatment resulted in retention of TSPC as well as in further increase of TAC. At the beginning and at the end of storage, romaine lettuce had higher TSPC as well as TAC than the iceberg lettuce.