Chemical and physical methods to reduce aflatoxin contamination in dried chili products in Thailand

Abstract

Aflatoxin, the mycotoxin produced by Aspergillus flavus, is the major problem of dried chili in tropical countries, like Thailand. Simple and applicable procedures to reduce aflatoxin contamination are urgently needed for dried chili producers and farmers. Two experiments with 2 chili cultivars were carried out during dry season, between January to April, and during rainy season, between May to August, 2014. Fresh chili fruits, 'KKU#2', the improved cultivar of the Plant Breeding Research Center for Sustainable Agriculture KKU, and 'Super Hot', the commercial cultivar of East West Seeds Co., Ltd., were harvested at ripe mature stage. For the 1st experiment in dry season, fresh fruit were treated with the chemical by soaking in commercial bleach solution, sodium hypochloride (NaOCl), 0 (control treatment), 0.25, 0.5, 0.75, and 1%, for 5 min and rinsed with running water for 10 min. In the 2nd experiment in rainy season, fresh fruits were treated with physical method by soaking in boiling water (100°C) for 0 (control treatment), 1, 2 and 3 min. The treated fruits of both experiments were sun-dried and oven-dried at 80°C thereafter. Dried fruits were stored in plastic bag at room temperature. Aflatoxin and pungency, as well as color of dried products were monthly determined for 3 months. The results showed that both chemical and physical methods did not affect pungency of dried chili products. Chemical treatment did not affect colour while the physical method enhanced the darker red colour of dried chili products compared to the control treatment. Nevertheless, all treatments used did not clearly reduce the contents of aflatoxin. Thus, the effects of season on drying and period of time for chemical soaking is currently discussed. Besides, the appropriate concentration of NaOCl is 0.5-0.75%, while soaking time in boiling water is 2 min.