Abstract:

The preservative effect of salicylic acid (SA) and hydrogen peroxide (H2O2) treatments on fresh-cut broccoli
was investigated. Fresh-cut broccoli was dipped in 0.5 mmol/L SA and 0.15 mmol/L H2O2 for 10 and 5 min, respectively.
Antioxidative enzyme activities, reactive oxygen species level, antioxidative substance content and senescence physiological
indicators during 4 days of storage at 20 ℃ were measured. Both treatments could effectively maintain the sensory quality
of fresh-cut broccoli florets. Compared with the control group during the storage period, fresh-cut broccoli florets treated
with SA had higher activities of superoxide dismutase (SOD), ascorbate peroxidase (APX) and peroxidase (POD), and lower
catalase (CAT) activity. Besides, the generation rate of superoxide anion free racial (O2-·) was smaller, and the content of
H2O2 was higher. The contents of ascorbic acid (AsA), carotenoid (Car) chlorophyll (Chl) and protein (Pro) were higher, and
malondialdehyde (MDA) was less abundant. Likewise, fresh-cut broccoli florets treated with H2O2 presented higher activities
of SOD, APX, POD and CAT. The generation rate of O2-· and H2O2 content were lower. An increase in the contents of
AsA, Car, Chl and Pro and a reduction in MDA content were observed in response to H2O2 treatment. Further comparison
demonstrated that SA treatment had a larger effect on these antioxidative indicators than H2O2 treatment. The results also
showed that the mechanism for inhibiting senescence and effectively maintaining the sensory quality of fresh-cut broccoli by
SA and H2O2 treatments was associated with improving antioxidative enzyme activities and alleviating biological oxidation
of reactive oxygen species. Therefore, SA treatment can inhibit the activity of CAT and improve the level of endogenous
H2O2 during the early stage of storage, and the preservative effect of 0.5 mmol/L SA is better than that of 0.15 mmol/L H2O2.

Key words: fresh-cut broccoli, salicylic acid, hydrogen peroxide (H2O2), antioxidative properties