Effect of storage temperature on quality changes of minimally processed baby lettuce

Leafy vegetables play an important role in the ready-to-eat industries. Lettuce is one of the most used vegetables for fresh-cut production. The young harvesting stage affects the postharvest physiology and behaviour. This work was focused on the quality changes of baby lettuce (Lactuca sativa L., var. acephala tipo Batavia cv. Rubia flavia) stored at 4 or 10°C for 14 days. During storage physiological and biochemical analyses were carried out. Leaf quality was determined by measuring: ascorbic acid, dehydroascorbic acid, chlorophyll, carotenoids, phenols, sucrose, ethylene production and lipid peroxidation. Lipid peroxidation increased by increasing storage temperature and time. Initial values of TBARS were 0.27 nmol g-1 FW and increased to 0.36 or 0.49 nmol g-1 in leaves stored at 4 or 10°C, respectively. Ascorbic acid content at beginning of experiments was 4.5 nmol g-1 FW but strongly declined and almost disappeared after 5 days of storage in both storage temperature conditions. Total ascorbic acid slightly decreased and increased again after 7 days of storage. The values ranged between 18.6 and 25.8 nmol g-1 FW. Ethylene production was very low during storage, below 50 pmol kg-1 s-1. Ethylene accumulation slowly decreased from 1000 to 300 nmol kg-1 L-1. Total chlorophyll and carotenoids did not change during storage in both temperature conditions. The AsA content rapidly drops within 5 days of storage. It can be considered a biochemical marker of produce freshness. Total ascorbate does not decrease during storage and produce may still have a beneficial effect on the human health.