Stockpiling of in-hull almonds has become more common as a result of increased crop sizes and the need to extend the processing season to maximize the use of processing facilities. Certain conditions in the stockpile, however, can lead to the growth of aflatoxin-producing molds such as Aspergillus flavus and A. parasiticus.
Aflatoxin is a major concern for the almond industry because of increasingly stringent maximum limits for aflatoxin contamination in key export markets. In recent studies to determine conditions that lead to mold growth, samples were taken of in-hull almonds from the top of the pile, upper mid-pile, lower mid-pile and at the bottom of the pile. The almonds were analyzed for moisture content, mold growth and the presence of aflatoxin.
Researchers found that the most significant factor for mold growth is the moisture content of in-hull almonds when they go into storage. Stockpiling in-hull almonds with a total fruit moisture of 9 percent or higher can lead to problems. They also found that the outer areas of the piles, where considerable condensation builds up, produced ideal conditions for mold growth.
Current research results suggest that you should not stockpile in-hull almonds that have a total moisture content exceeding 6.5-7 percent.
Stockpiles should be properly maintained to prevent condensation, pooling of water and mold growth. It is important to open the piles during the daytime when relative humidity is lower, and close them at night when relative humidity tends to be high.
Stockpile monitoring research continues to be conducted and researchers hope to refine stockpiling guidelines in the near future.
Aflatoxin Affects Food Safety