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OMA 2014.10 C: Collaborative Study Manuscript Expert Review Panel Use Only September, 2017

2013 Dietary Starch in Animal Feeds Collab Study Protocol 072513

LABORATORY VALIDATION: The following describes the starch method for collaborative study with texts derived from the peer reviewed study reports on the starch method and glucose detection method that were published in the January/February 2009 edition of J. AOAC Int. Volume 92(1). The original papers are appended. 1. Method Determination of Starch, Including Maltooligosaccharides, in Animal Feed: Comparison of Methods and a Method Recommended for AOAC Collaborative Study M. B. Hall U. S. Dairy Forage Research Center, USDA-Agricultural Research Service 1925 Linden Drive, Madison, WI, USA 53706 Factors Affecting Accuracy and Time Requirements of a Glucose Oxidase–Peroxidase Assay for Determination of Glucose M. B. Hall U. S. Dairy Forage Research Center, USDA-Agricultural Research Service 1925 Linden Drive, Madison, WI, USA 53706 N. S. Keuler Statistics, Computing & Biometry, University of Wisconsin - Madison 1300 University Avenue, Madison, WI 53706 ABSTRACT Starch is a nutritionally important carbohydrate in feeds that is increasingly used for formulation of animal diets and therefore demand for analytical measurement is also increasing. Discontinued production of the enzyme Rhozyme-S required for AOAC method 14.075 invalidated this method for starch in animal feeds. The objective of this study was to compare methods for the determination of starch as potential candidates as a replacement method and for an AOAC collaborative study. Many starch methods are available, but they vary in accuracy, replicability, and ease of use. After evaluating assays that differed in gelatinization method, number of reagents, and sample handling, and excluding assays with known methodological defects, 3 enzymatic-colorimetric assays, including an extension of AOAC method 996.11, were selected for comparison. The assays all used two-stage heat-stable, α -amylase and amyloglucosidase hydrolyses, but differed in gelatinization solution (heating in water, 3-( N -morpholino) propanesulfonic acid buffer, or acetate buffer). As performed, the measured values include both starch and maltooligosaccharides. The acetate buffer-only method was performed in sealable vessels and yielded greater starch recovery (2 to 6 percentage units of sample dry matter) on feed/food substrates than did other methods. This method is a viable candidate for a collaborative study. AOAC Research Institute ERP Use Only

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