Abstract:

This study aimed to investigate the effect of freezing-point storage on antioxidation capacity and preservation
of postharvested lettuce. Lettuce were packaged into microporous PE bags and stored at (−0.5 ± 0.2) ℃ for 15 days after
pre-cooling at 4 ℃ for 8 h. The changes in ascorbate peroxidase (APX) and catalase (CAT) activities, ascorbic acid (AsA)
and H2O2 contents, superoxide anion radical formation rate, malondialdehyde (MDA) content, membrane permeability,
respiration intensity, weight losses rate and chlorophyll content were measured. The results indicated that compared
with the traditional storage, freezing-point storage induced an increase in endogenous H2O2 content at the beginning of
storage, enhanced the activities of APX and CAT, postponed the decrease of ASA content, and inhibited the accumulation
of superoxide anion radical, MDA content, respiration intensity, weight losses rate and chlorophyll content. These results
suggest that freezing-point storage may inhibit the metabolic rate and enhance the antioxidant capacity of lettuce, thus
improving its storage quality.

Key words: freezing-point, lettuce, antioxidant capacity, preservation