Effect of some chemical and herbal compounds on growth of Aspergillus parasiticus and aflatoxin production

The anti-fungal properties of a series of chemical and herbal compounds at different levels was tested on potato dextrose agar. Among the chemical compounds, propionic acid at 0.1–0.5%, ammonia at 0.5%, copper sulphate at 0.08–0.5% and benzoic acid at 0.1–0.5% completely inhibited Aspergillus parasiticus growth. Urea, citric acid and sodium propionate had moderate anti-fungal properties (36–64% reduction). Among the herbal compounds, clove oil at 0.5% completely inhibited fungal growth. Compounds which inhibited fungal growth by at least 20% were selected to test their efficacy to inhibit fungal growth and aflatoxin production in feeds. All the selected chemical and herbal compounds reduced (P<0.01) fungal growth (i.e. fungal spore count) and aflatoxin production. Propionic acid at 0.05–0.5%, sodium propionate at 0.1–0.5%, benzoic acid at 0.2% and ammonia at 0.5% completely inhibited aflatoxin production. Reduction in aflatoxin production was high with 0.5–1% citric acid (91–94%), 0.1–0.5% urea (93–96%) and 0.08% copper sulphate (85%). Clove oil at 0.5–1% inhibited aflatoxin production completely. Moderate reduction in toxin production occurred with 0.2–1% turmeric (63–84%), 0.1–1% onion (64–76%) and 0.2–1% garlic (71–84%). Among the chemical compounds tested in feeds, propionic acid, sodium propionate, benzoic acid and ammonia were the best anti-fungal compounds, followed by urea and citric acid. Among the herbal compounds, clove oil was the best followed by turmeric, garlic and onion.