CONICET | Buscador de Institutos y Recursos Humanos

The use of irradiation to sanitize fresh-cut fruit surfaces has received increasing attention. In particular, ultraviolet light (UV-C) has been proposed as a germicidal factor to inactivate microorganisms, retard microbial growth, increase shelf life and maintain adequate sensory and nutritional characteristics during storage. The objective of this work was to study the changes in color of UV-C irradiated apple slices and to investigate the use of some pretreatments in order to minimize enzymatic browning during refrigerated storage. Apples slices (3 cm diameter, 0.6 cm thickness) were placed at 10 cm distance from two UV-C lamps (15 W) inside a wooden box covered with aluminum foil, where they were exposed to irradiation during different periods of time (2-25 min). The UV-C light dose received after each treatment (15-145 kJ/m2) was measured by the iodide-iodate chemical actinometer. Irradiated samples were compared to an unprocessed control throughout a week of storage at 4-5 ºC in closed plastic trays. Two processes applied prior to irradiation for inhibition of enzymatic activity were also investigated: 1) blanching in water (80 ºC, 5.5 min or 100 ºC, 1 min) and 2) dipping in a 1 % (w/v) ascorbid acid + 0.1 % (w/v) calcium chloride solution for 5 min at 4ºC. At selected intervals (0, 3 and 7 days), tristimulus color measurements were made on ten treated samples for each condition. An increase in superficial browning was observed in irradiated samples throughout storage as compared to the control, especially at greater doses. Both pretreatments helped in maintaining the original color of apple slices after UV-C light exposure, although blanching was less effective in controlling browning than the anti-browning dip. Results indicated that UV-C light combined with a suitable anti-browning pretreatment can be used as a tool by the fresh produce industry to avoid color deterioration during storage.