UV‐C irradiation delays browning of fresh‐cut “Fuji” apples

Abstract

In order to explore the effect and the corresponding physiological mechanisms of UV-C irradiation on browning of fresh-cut apples, both whole and sliced apple were irradiated with UV-C (254 nm) for 5 min before or after processing. The browning index (BI) of slices was immediately measured, while other relevant physiological parameters were evaluated on quick-frozen samples during refrigerated storage. Results indicated that both pre- and post-processing UV-C treatments effectively delayed browning of apple slices; nevertheless, post-processing UV-C treatment was more efficient. BI significantly negatively correlated with non-enzymatic capacities, and activities of catalase, ascorbate peroxidase, and glutathione reductase (GR). BI was positively correlated with the contents of H2O2 and malondialdehyde (MDA). These findings suggested that UV-C treatment delayed browning of apple slices during cold storage by improving the antioxidant system. Post-processing UV-C treatment was more efficient than pre-processing. Practical applications UV-C treatment is a technique of preservation for fresh-cut fruits. It is widely applied in food processing and many other fields due to its convenience, safety, low cost, etc. In the present study, both pre- and post-processing UV-C (254 nm) irradiation for 5 min could (1) delay the browning of fresh-cut apple, (2) improve the polyphenol oxidase activity and reduce the phenylalanine ammonia-lyase (PAL) activity and total phenolic content (TPC), and (3) reduce the accumulation of H2O2 and malondialdehyde, and increase the antioxidant activities of fresh-cut apples. Thus, UV-C treatments maintain the fresh-cut quality of fresh-cut apple slices and extend their shelf life.