Improving the quality of fresh-cut melon through inactivation of degradative oxidase and pectinase enzymatic activities by UV-C treatment

摘要

This work investigated the effect of exposure of fresh-cut melon (Cucumis melo L. var. reticulatus) to ultraviolet-C (UV-C, 254 nm, 0.04 kJ s~(-1) m~(-2)) radiation for different times (30, 60, 120 s) on main degradative enzymatic activities (polyphenol oxidase, peroxidase, pectin methylesterase and polygalactu-ronase) and quality parameters (firmness, colour) during storage at 5 ℃. Enzymatic activities in samples washed with water and treated with UV-C radiation were similar to samples washed with 100 mg L~(-1) NaOCl and significantly lower than untreated samples, especially after 7 days of storage at 5 ℃. Tissue softening was noticed in all samples although those treated with UV-C light resulted 7-12% firmer than untreated ones. The lowest perceptible colour variation, expressed as △E~*, was in samples exposed to 120 s radiation (△E = 8.58), while the highest value was noticed in untreated sample (△E = 11.06). Postcut UV-C fruit treatment was effective in extending the shelf life of minimally processed 'Galia' melon.