Effect of disinfestation-dose irradiation on the physiology of Tai So lychee

Abstract

Tai So lychees (Litchi chinensis Sonn.) were irradiated at 0, 75 or 300 Gy in replicated experiments using a -6-0Co source. Fruit were analysed shortly after irradiation and again after 3 wk storage at 5 degree C for external colour, internal colour, soluble solids, pH, titratable acidity, vitamin C and eating quality. Respiration rates were monitored from 4 to 10 days after irradiation. Disease levels were determined 22 days after irradiation. Irradiation had virtually no effect on any of the physical, chemical or organoleptic parameters investigated. Incidence of disease caused by Colletotrichum sp. was reduced by doses of 75 and 300 Gy but unidentified species were increased. Gamma irradiation of lychees at 75 or 300 Gy may be used for disinfestation purposes with no adverse effects on fruit quality.