ARS | Publication request: IMPORTANCE AND PITFALLS OF STARCH ASSAYS: SELECTION OF METHODS

Submitted to: Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: May 2, 2008
Publication Date: June 9, 2008
Citation: Hall, M. 2008. Importance and pitfalls of starch assays: selection of methods. In: Proceedings of the Annual Meeting of the Midwest Section of the American Association of Analytical Chemists, June 9-11, 2008, Bozeman, Montana. p. 20.

Technical Abstract: Starch analyses provide valuable information on diverse samples, from nutritional values of human foods and animal feeds to data for estimating yields of ethanol from grain. However, starch methods differ in their efficacy, with common methods differing in recovery by 3 to 7 percentage units. Reduced recovery is associated with incomplete gelatinization, physical barriers to enzymatic attack (e.g., formation of sample microgels or lumps), hydrolysis of samples at neutral pH, microbial predation of glucose, and grinding methods that do not adequately reduce particle size. Inflated starch values are usually associated with detection of glucose from nonstarch sources. To maximize accuracy, samples should be ground to pass the 0.5-mm screen on cutter mills, hydrolyses should be performed at mildly acidic pH (pH 4.5-5.0), and end-product detection should be specific for glucose released from starch. Methods that minimize handling and transfers can also increase accuracy and throughput.