Substrate suitability of neem seed kernel for the growth and elaboration of aflatoxins by <i style="mso-bidi-font-style: normal">Aspergillus parasiticus </i>(NRRL 2999)

Abstract

Neem seed kernels artificially infested with <i style="mso-bidi-font-style:normal">Aspergillus parasiticus </i>(NRRL 2999) was evaluated for aflatoxin elaboration and fungal growth, and compared with groundnut, a high risk commodity for aflatoxin contamination. At optimal moisture content (10-12%) the total, individual toxins (AFB₁, AFB₂, AFG₁and AFG₂) and ergosterol content increased and showed maximum levels on day 9. Crude protein and polyphenols increased while, fat and total sugar content decreased during the period of infection. The protein content correlated positively (<i style="mso-bidi-font-style:normal">r</i> = 0.734) with total toxin levels, whereas fat content (<i style="mso-bidi-font-style:normal">r</i> = -0.761) and total sugars (<i style="mso-bidi-font-style:normal">r</i> = -0.891) showed negative correlation and they were all statistically significant (<i style="mso-bidi-font-style:normal">p<</i>0.01). The polyphenols showed negative and non-significant correlation with total toxin levels. Azadirachtin one of the major active principles of neem seed kernel showed significant decrease on day 3 (<i style="mso-bidi-font-style: normal">P</i><0.05) and day 6 (<i style="mso-bidi-font-style:normal">P</i><0.01). Neem seed kernel has shown 54 and 74% less aflatoxin production on day 9 and 12, respectively in comparison to groundnut seeds. Ergosterol content also showed 60% decrease on day 9, conferring it a poor substrate for fungal growth and aflatoxin elaboration.