Effect of blanching on aflatoxin contamination and cross-contamination of almonds.

Blanching of almonds was examined for reducing aflatoxin content of contaminated nuts.  Almonds with intact pellicles were spiked with aflatoxin B 1 (AFB 1 ) and blanched at 85°C.  Following blanching, almond kernels and pellicles contained 20% and 19% of spiked AFB 1 , respectively.  Blanching water contained an additional 41% of spiked AFB 1 .  In a separate study, post-blanching water was spiked with AFB 1- and used for subsequent blanching of uncontaminated almonds.  The resulting blanched kernels acquired 3.3% of the AFB 1 from the spiked water, demonstrating a low level of cross-contamination from reused contaminated blanching water.  The effect of blanching temperature on partitioning of AFB 1 from almonds to blanching water was significant at 20 ppb spiking level, but not at 100 ppb.  AFB 1 levels that were unaccounted for in mass balance of blanching components were presumed to be lost due to binding to water-solubilized almond components, and were independent of pH and blanching time.  Blanching reduced total aflatoxins in naturally contaminated almonds by 13-76%, depending on almond quality as well as blanching time and temperature.  These results indicate that the association between almond components and aflatoxin generated through mold contamination is more complex than in spiking experiments.