S23 - Session O1 - Effects of X-ray and Gamma ray Irradiation on the Physico-chemical Qualities of Mango cv. Nam Doc Mai Si Thong (Mangifera indica L.)

Authors: Peerasak Chaiprasart *, Phongrapi Wichitkunanan, Noppharat Intha, Nutchanat Phakdee, Boonsong Saeng-on, Suwimol Jetawattana

'Nam Doc Mai Si Thong' mango is the major variety produced in Thailand. Its apparent sweetness when ripe (16 n 18 %Brix), creamy pulp, attractive golden peel color, and thin peel make it popularly desired by international trade. Apart from Vapor Heat Treatment (VHT) and Hot-Water Treatment (HWT), good practices in post-harvest combining with irradiation are usually required for fresh mango as a quarantine measure in some countries. However, the overlook of good post-harvest treatments prior to irradiation usually causes poor qualities of mango when they arrive at their destinations. Subsequently causes the misunderstanding blamed for the generic dose of 400 Gray (Gy) by the exporters. Here we show phytosanitary irradiations combining with good practices in post-harvest are essential to maintain physico-chemical properties of mangos. It was found that sorting of mango using Near Infrared Spectroscopy (NIR) helps in selection maturity stage at 80% (7 n 13 %Brix) with the predicted R 2 values 0.96 for total soluble solids (TSS). X-ray and gamma ray irradiations at 400 Gy significantly decreased ethylene productions and respiration rates then delayed mango ripening up to 12 days relative to non-irradiated control and they provided no different effect in physico-chemical characteristics. Systemic fungicide soaking (300 ppm) in hot water (45 °C) effectively decreased rates of anthracnose incidence in irradiated mango and to less than 5% relative to non-treated. Our results demonstrate the phytosanitary irradiation combined with good practices in post-harvest processes are reliable in maintaining premium qualities of mangos during storage. We anticipate our results to be a starting point for good practices in post-harvest for 'Nam Doc Mai Si Thong' mango and other varieties of mango for export. Furthermore, premium qualities of 'Nam Doc Mai Si Thong' mango and its prolonged shelf life can considerably provide confidence in commercial scale to exporters.