Introduction
Rice is the staple food among Sri Lankans. However, specific conditions of temperature, relative humidity and moisture content of rice, which arise during storage, may contribute to the rapid deterioration of stored rice by promoting fungal growth (Christensen and Saucer 1992). Fungal infections may discolour grains, change its chemical and nutritional characteristics, reduce germination and most importantly, contaminate it with mycotoxins, such as aflatoxins which are highly toxic to man and animals (Paster et al. 1993). Aspergillus flavus Link. is one of the major storage fungi found regularly in important cereals cultivated in the world (Paster 1995), which produces aflatoxins such as aflatoxin B1, B2, G1, G2 (http://vm.cfsan.fda.gov/mow/chap41.html). Breckenridge et al. (1986) reported that aflatoxin B1(AFB1) was detected in rice, and 96% of the parboiled rice samples tested contained AFB1. Though the aflatoxin content in these samples were below the UNICEF/WHO/FAO permissible levels, the contamination is very critical even at low levels, as rice is consumed in significant quantities. As rice is a good substrate for aflatoxin B1 production, the importance of research work in controlling the growth of A. flavus and aflatoxin contamination of the stored rice was investigated (Ilago and Juliano 1982).