ARS | Publication request: Effect of UV-B light on soluble phenolic content and antioxidant capacity of selected fresh-cut fruits and vegetables

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: February 9, 2012
Publication Date: N/A

Technical Abstract: The application of wounding followed by ultraviolet (UV-B) light exposure to enhance the nutrient content of specialty crops by stimulating the synthesis of secondary metabolites was evaluated. In this continuing screening study of several fresh-cut produce, both top and bottom surfaces were exposed to different total energy doses and bimodal peak UV-B irradiances and then incubated at 10-15°C for 3-7 days to allow for a biological response to the stresses. Response to treatment conditions for each specialty crop was assessed in terms of total soluble phenolic contents (TSP) and antioxidant capacity (AC). Sample groups included Red and Golden Delicious apple wedges, two Roma tomato varieties (HZ9780 and HMX7883) cut in halves, and two root crops, sweet potato and two varieties of parsnip grown on clay and sandy soils, sliced at 3 mm thickness. Apples did not respond to the wounding stress or UV-B exposure at 128, 318 and 945 mJ/cm2 after storage for 3 days at 15°C. Tomato HZ9780 had higher initial TSP. Wounding stress, but not UV-B exposure at 61 and 116mJ/cm2, induced 2-fold increase in TSP after 3 days at 10°C plus 4 days at 2°C. TSP of HMX7883 tomato halves remained unchanged after same treatment and storage conditions. Also, wounding stress but not UV-B exposure at 135, 336 and 1005 mJ/cm2, caused 1.4-fold increase in TSP of sweet potato slices after 7 days of storage at 15°C. Both variety and soil type affected the positive response of parsnip slices to wounding and UV-B exposure at 128.5 mJ/cm2. TSP and AC of parsnip slices showed significant 2.1- and 3.0-fold increase, respectively, due to the combination effect of wounding and UV-B light exposure after 3 days incubation at 15°C. UV-B light exposure can be used as an additional processing step on selected specialty crops to enhance their nutritional value.