Aflatoxin Content of Single Peanut Kernels in Commercial Lots and in Kernels Artificially Infected with Aspergillus parasiticus.

During peanut processing, further removal of aflatoxin-contaminated kernels from electronically sorted and unblanched commercial lots was achieved by color sorting of the kernels after light roasting and deskinning. A modified procedure for efficient recovery of aflatoxin from an individual kernel in a small-scale system was applied for analysis of discolored kernels sampled over 3 consecutive years in Taiwan. The highest and average aflatoxin contents in 60 kernels sampled each year were 1,930 and 150 ppb in 1994,4,040 and 160 ppb in 1995, and 410 and 32 ppb in 1996, respectively. In 1994, 1995, and 1996, 66.7, 85.0 and 61.7%, respectively, of the kernels tested contained aflatoxins; 16.7, 13.3, and 6.7% contained 50 to 100 ppb and 16.7, 15.0, and 10.0% contained more than 100 ppb. Enhanced aflatoxigenic mold infection and aflatoxin production were monitored in peanut kernels artificially inoculated with Aspergillus parasiticus at various inoculum concentrations and incubated under 100% relative humidity at 28°C or at ambient temperature for various periods. In all cases, aflatoxin content deviated tremendously from kernel to kernel. The highest aflatoxin content observed in a single kernel was 945,000 ppb. In uninoculated kernels incubated in the same conditions, the growth of naturally occurring mycoflora was observed; the highest aflatoxin content was 5,190 ppb.