Production of aflatoxin on peanuts under controlled environments

Diener, U.L. and Davis, N.D. (1969) Production of aflatoxin on peanuts under controlled environments. Journal of Stored Products Research, 5 (3). pp. 251-258.

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The influence of temperature, relative humidity, nature of the substrate, atmospheric gases, and other factors on growth and aflatoxin production by Aspergillus flavus in peanuts, Arachis hypogaea L. variety ‘Early Runner’, was investigated under controlled environments. Sound or broken mature kernels, immature kernels, and unshelled peanuts were inoculated with spores of A. flavus and incubated in 98 ± 1 per cent r.h. at temperatures ranging from 10 to 45°C, and also 30 ± 0·5°C in relative humidities ranging from 70 to 99 per cent. The substrate was either heat-treated (sterile) cured peanuts, surface-sterilized pods of freshly dug peanuts, or unsterile cured peanuts. Surface-sterilized, sound mature kernels were used in studies with atmospheric gases. Samples were removed after 7, 21, 42 or 84 days and assayed for aflatoxin, free fatty acids, and kernel moisture. The limiting relative humidity for aflatoxin production was 83 ± 1 per cent or higher at 30°C, varying with the substrate and length of the incubation period. The lower limiting temperature was 11–12 ± 1°C, whereas the upper limiting temperature was 40·5 ± 0·5°C at 98 ± 1 per cent r.h. Living peanuts in the shell were slightly less susceptible to invasion and aflatoxin formation than shelled kernels or heat-killed peanuts. Aflatoxin production in sound mature kernels decreased with increasing concentrations of CO2 from 0·03 to 100 per cent. Reducing O2 concentrations generally reduced aflatoxin production. Notable decreases in aflatoxin resulted when O2 was reduced from 5 to 1 per cent in combination with 0, 20 or 80 per cent CO2. Lowering temperature or relative humidity from optimum also reduced aflatoxin production. Aflatoxin production varied with strain of the fungus, maturity of the peanut, shake or stationary culture, and microbial interactions. Free fatty acid formation paralleled fungus growth rather than aflatoxin synthesis.

Item Type: Article
Additional Information: SNNigams Collection
Author Affiliation: Botany and Plant Pathology Department, Auburn University Agricultural Experiment Station, Auburn, Alabama, U.S.A.
Subjects: Plant Protection
Environmental Science > Environment
Divisions: Groundnut
Depositing User: Mr T L Gautham
Date Deposited: 13 Jul 2013 12:59
Last Modified: 13 Jul 2013 12:59
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