Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/30/2006
Publication Date: 12/30/2006
Citation: Whitaker, T.B., Slate, A.B., Hurley, M.J., Giesbrecht, F.G. 2006. Sampling Almonds for Aflatoxin, Part II: Estimating Risks Associated with Various Sampling Plans Designs. Journal Association. Official Analytical Chemists, International 90 (3):778-785. Interpretive Summary: Aflatoxin is a carcinogenic and toxic compound produced by molds found in several agricultural commodities such as peanuts, cereals, and treenuts. Regulatory agencies worldwide have established a maximum limit for aflatoxin in foods as a method to reduce aflatoxin contaminated foods. In the United States, the FDA has established a limit of 20 parts per billion total aflatoxin. As a result, almonds are inspected by exporters, importers, processors, and food manufacturers to detect and remove contaminated lots from the food chain. It is difficult to determine aflatoxin levels of large shipments or lots because of the errors associated with sampling, sample preparation, and analysis, collectively called the aflatoxin test procedure. Errors associated with the aflatoxin test procedure results in some lots being misclassified. Some of the good lots test bad and some of the bad lots test good. A method was developed to evaluate the number of lots misclassified by a specific aflatoxin-sampling plan. Examples of sampling plan designs were shown to demonstrate how to reduce the number of lots misclassified. The evaluation method will help processors and exporters reduce the number of lots misclassified. This will reduce both health risks to the consumer and economic loss to processors, exporters, and food manufacturers.
Technical Abstract: About 100 nations have established regulatory limits for aflatoxin in food and feeds. Because these limits vary widely from one country to another, FAO/WHO working through the Codex Committee on Food Additives and Contaminants (CCFAC) has initiated work to harmonize aflatoxin limits and sampling plans for aflatoxin in almonds, pistachios, hazelnuts, and Brazil nuts. Initially, studies were developed to measure the uncertainty and distribution among replicated sample test results taken from an aflatoxin- contaminated almond shipments. The uncertainty and distribution information was used to develop a model to evaluate the performance of aflatoxin sampling plan designs so that harmonized sampling plans can be developed for treenuts that reduce the risks of misclassifying lots in the export trade. Twenty lots of shelled almonds with varying levels of contamination were sampled according to an experimental protocol where sixteen 10 kg samples were taken from each lot. The observed aflatoxin distribution among the 16-aflatoxin sample test results was compared to two theoretical distributions. The negative binomial distribution was selected to model aflatoxin distribution among sample test results because it gave acceptable fits across all 20-sample distributions. Using the variance and distribution information, operating characteristic curves were developed to predict the effect of sample size and accept/reject limits on the chances of rejection of good lots and the acceptance of bad lots for various sampling plan designs.