Effects of gamma irradiation on pepper's volatile compounds sensory qualities and pest infestation control. Part of a coordinated programme in the Asian Regional Cooperative Project of Food Irradiation

The effects of gamma irradiation, packaging materials and storage time of black and white peppers on the infestation and reinfestation of microorganism and insects were evaluated. The samples were irradiated at the doses between 2 and 9 kGy. The packaging materials consisted of polypropylene woven bags laminated with thin polyethylene (PPE) and polyethylene bags (PE) of different thickness, 0.05, 01.2 and 0.17 mm. The jute bag was used as a control material. The changes of infestation and reinfestation status were observed for 6 months in Malaysia and for the next 2 months the changes were evaluated when the samples had reached Japan. Results obtained indicated that irradiation at a dose up to 9 kGy reduced the bacterial load of black pepper from 1.6x107/g to <102/g, while the dose of 6 kGy was required to reduce the population in white pepper from 2.3x104/g to <102/g. The original population of mould-yeast was relatively low (approx. 104/g) and could be reduced to <102/g at only 2 kGy. No problems and difficulties were faced with regard to the transportation of the peppers. However, prolonged storage time may encourage microbial growth, and 4 months of storage was a critical period for black pepper. Two species of Anobiidae infesting pepper had been identified, Lasioderma serricone (Fabricius) which made up 80% of the insect counts and Stegobium pamiceum (L.). However, at the doses applied and packaging materials used, there was no reinfestation for all but the material PPPE (no observation made for jute bags)