A comparison of low intensity UV-C and high intensity pulsed polychromatic sources as elicitors of hormesis in tomato fruit

Postharvest hormetic treatment of mature green tomato fruit (Solanum lycopersicum cv. Mecano) with high intensity pulsed polychromatic light (HIPPL) significantly delayed ripening to levels comparable to those achieved using a conventional low intensity UV-C (LIUV) source. A 16 pulse HIPPL treatment reduced the Delta TCI (tomato colour index) by 50.2% whilst treatment with a LIUV source led to a reduction of 42.8%. Moreover, the 16 pulse treatment also induced disease resistance in the fruit to Botrytis cinerea with a 41.7% reduction in disease progression compared to a 38.1% reduction for the LIUV source. A single 16 pulse HIPPL treatment was found to significantly reduce disease progression on ripe fruit with a 28.5% reduction in comparison to 13.4% for the LIUV treatment. It is shown here that delayed ripening and disease resistance are local responses in side-treated tomato fruit for both LIUV and HIPPL treatments. Finally, utilising a 16 pulse HIPPL treatment would reduce treatment times from 370 s for LIUV sources to 10 s per fruit - a 97.3% reduction. (C) 2016 Elsevier B.V. All rights reserved.