UV-C treatments enhance antioxidant activity, retain quality and microbial safety of fresh-cut paprika in MA storage

Abstract

Fresh-cut paprika was treated with 245 nm UV-C irradiations of 7, 15, and 28 kJ·m-2, packaged using a laser ablation breathable film with permeability of 20,000 mL O2·m-2·day-1·atm-1, and was stored in general distribution temperature at 8°C. The paprikas were evaluated antioxidant activity and internal quality, reducing microbial populations, modifying composition of CO2, O2 and ethylene content in packages. Fresh-cut paprika irradiated with 15 kJ·m-2 UV-C has shown the lowest fresh weight loss and highest overall quality during MA storage. The gas composition (CO2 and O2 concentrations) of UV-C 15 kJ·m-2 treatment showed the closest conditions to CA conditions of paprika. All UV-C treatments presented higher ethylene concentration in package as compared to those of the control as well as NaOCl treatment, because the ethylene content was elevated in response to abiotic stress, possibly by the treatment of UV-C in paprika. After 7 days of storage at 8°C, the antioxidant activity (DPPH activity), total phenolic compound and vitamin C contents of fresh-cut paprika were maintained highest by UV-C 15 kJ·m-2 treatments, followed by 7 kJ·m-2 and 28 kJ·m-2. The microbial population was reduced by UV-C treatment on the 7 days of MA storage, with the fungal incidence rate lowest in 15 kJ·m-2 and 28 kJ·m-2 UV-C treatment and total bacterial numbers showed the lowest in UV-C 15 kJ·m-2 treatment representing lower than 6.0 log CFU·g-1 which was the reference limit for microbial contamination. These results suggest that the application of UV-C 15 kJ·m-2 on fresh-cut paprika represents the most favorable results of gas composition in package, antioxidant capacity (e.g., vitamin C contents) and sterilization of fungi and bacteria during MA storage, and extending the shelf life.