Submitted to: Journal of the Association of Official Analytical Chemists
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/27/2005
Publication Date: 7/12/2005
Citation: Whitaker, T.B., Slate, A.B., Trucksess, M.W., Williams, K.M., Brewer, V.A., Whittaker, P.J., Heeres, J.T. 2004. Variation of analytical results for peanuts in energy bars and milk chocolate. Journal of the Association of Official Analytical Chemists. Interpretive Summary: Peanut proteins can cause severe allergic reactions to some sensitized individuals. There may be occasions during the manufacturing process when foods may become unintentionally contaminated with small amounts of peanut proteins. To avoid accidental ingestion of peanut contaminated foods by consumers, the U.S. Food and Drug Administration is developing an inspection program to detect allergenic proteins in foods. Because of the inherent errors associated with sampling, sample preparation and analytical steps of the test procedure used to measure protein in foods, some contaminated lots may not be detected. A study was conducted that determined the magnitude of variability associated with the sampling, sample preparation, and analytical step of the test procedure to measure peanut proteins in energy bars and milk chocolate. Knowing the variability associated with each step of the test procedure, test procedures can be designed to reduce variability which will reduce the number of contaminated lots not detected by the inspection program. Improving test procedures used to measure peanut proteins in foods will reduce the number of contaminated lots not detected by the inspection program and provide a safer food supply for the consumer.
Technical Abstract: Peanuts contain proteins that can cause sever allergic reactions to some sensitized individuals. Studies were conducted to determine the recovery of an ELISA type analytical method to measure peanut protein and determine the sampling, subsampling and analytical variances associated with testing energy bars and milk chocolate for peanuts. Food products containing chocolate were selected because of the high sugar content which makes sample preparation for subsampling difficult. Peanut contaminated energy bars, on-contaminated energy bars, incurred (spiked) milk chocolate containing known levels of peanut and peanut free milk chocolate was used. A commercially available enzyme-linked immunoassay (ELISA) kit was used for analysis. The sampling, sample preparation, and analytical variances associated with each step of the test procedure to measure peanut protein were determined for energy bars. The sample preparation and analytical variances were determined for milk chocolate. Variances were found to be functions of peanut protein concentration. Sampling and sample preparation variability associated with energy bars accounted for 96.6% of the total testing variability. Sample preparation variability associated with powdered milk chocolate accounted for more than 60% of the total testing variability. The variability among peanut test results can be reduced by increasing sample size, subsample size and number of analyses. For energy bars, the effect of increasing sample size from one to four bars, subsample size from five to 20g, and number of aliquots quantified from one to two on reducing the sampling, sample preparation, and analytical variance was demonstrated. For powdered milk chocolate the effect of increasing subsample size from five to 20g and number of aliquots quantified from one to two on reducing sample preparation and analytical variance were demonstrated. This study serves as a template for application to other foods, and extrapolation to different sizes of samples and subsamples as well as number of analyses