Radiation disinfestation of dry leaf tobacco and coffee beans

Preliminary tests conducted to determine the effect of gamma radiation in Araecerus fasciculatus De Geer indicated little differences in the mortality of insects exposed to 0.10-0.40 kGy. Other insects in the 2 kg bean lots were minimally affected by a dose of 0.05 kGy, but doses of 0.10-0.40 kGy resulted in nearly complete mortality. In 60 kg jute bags of export coffee exposed to 0.665-0.958 kGy, all the insects were dead when examined 1 month after irradiation. At 6 months, most of the untreated beans were damaged. In 15 kg tin cans, all the insects in both the irradiated and untreated cans were dead within 1 month; the insects in the untreated cans probably died from lack of oxygen and an increase in carbon dioxide. Irradiation had no detectable effect on the caffeine, fat and moisture contents, or on the pH. No moisture was gained by the coffee beans in cans, while the moisture in beans in jute bags increased from 9.6% to about 13.7% within 1 month. Export bales of leaf tobacco (about 100 kg, 100 cm x 75 cm x 40 cm) were artificially infested with Lasioderma serricorne (F.) and irradiated with 0.30-0.60 kGy at a rate of 0.5-1.0 kGy per hour. The bales were repositioned 12 times to provide thorough exposure to the gamma rays. There was no increase in the number of insects during the 6 months of storage; however, live insects were found at 2 months. Live insects found at the initial examination in phosphine fumigated bales indicated inadequate fumigation. A dose of 5 kGy had no effect on the nicotine content, the volatile oil content or composition, or the pH. (author). 11 refs, 3 figs, 10 tabs