UV-C light preserves quality of minimally processed watermelon cylinders

Watermelon (Citrullus lanatus) is usually minimally processed as cubes, edgecut damage being a remarkable defect. To avoid such disorder, processing as cylinders and using UV-C as sanitizing tool can be an interesting alternative to preserve quality during shelf life. The effect of UV-C radiation on overall quality, microbial growth, phenolics content and lycopene concentration of watermelon cylinders (2.7 cm ¿) of several lengths (1, 2, 4 and 8 cm) were analyzed. After harvesting, fruits were washed (150 ¿L L-1 NaClO), precooled and processed at 8°C. Once removed the skin, fruits were manually cut as cylinders, exposed to 4.79 kJ UV-C m-2 and packaged in polypropylene packages under passive modified atmosphere. UV-C untreated cylinders were used as control. After 7 days at 5°C, O2 partial pressure was higher for the longest cylinders (17.9 kPa for 8 cm vs. 14.2 kPa for 1 cm) with the lowest CO2 partial pressure (3 kPa for 8 cm vs. 7.4 kPa for 1 cm), indicating a higher respiration rate for the smaller sizes. A better sensory quality in 8 cm cylinders for both, control and UV-C treated, was observed. However, microbial growth was better controlled and phenolics content better maintained (60-80 mg CAE kg-1 fw) in UV-C treated samples. Lycopene content did not significantly decrease in any treatment. As conclusion, watermelon minimally processed as cylinders pretreated with 4.79 kJ UV-C m-2 can be stored for up to 7 days at 5°C without noticeable quality changes.