Measurement of Starch: Critical Evaluation of Current Methodology

• Published in: Starch - Stärke 2019-01, Vol.71 (1-2), p.n/a
• Main Authors: McCleary, Barry V., Charmier, Lucie M. J., McKie, Vincent A.
• Format: Article
• Language: English
• Subjects: Amylases; Analytical methods; animal feed; cereal grains; Complications; dietary starch; foods; Glucans; Glucoamylase; Glucose; Glucose oxidase; Hydrolysis; Isomerization; Maltose; Measurement methods; Peroxidase; Reagents; Starch; Sucrose; Sugar; thermostable α‐amylase; total starch; α-Amylase; β-Glucan
• ISSN: 0038-9056; 1521-379X
• DOI: 10.1002/star.201800146

Most commonly used methods for the measurement of starch in food, feeds, and ingredients employ the combined action of α‐amylase and amyloglucosidase to hydrolyze the starch to glucose, followed by glucose determination with a glucose oxidase/peroxidase reagent. Recently, a number of questions have been raised concerning possible complications in starch analytical methods. In this paper, each of these concerns, including starch hydrolysis, isomerization of maltose to maltulose, effective hydrolysis of maltodextrins by amyloglucosidase, enzyme purity and hydrolysis of sucrose, and β‐glucans have been studied in detailed. Results obtained for a range of starch containing samples using AOAC Methods 996.11 and 2014.10 are compared and a new simpler format for starch measurement is introduced. With this method that employs a thermostable α‐amylase (as distinct from a heat stable α‐amylase) which is both stable and active at 100 °C and pH 5.0, 10 samples can be analyzed within 2 h, as compared to the 6 h required with AOAC Method 2014.10. Commonly employed methods for starch analysis have been critically evaluated to ensure starch is measured accurately. Factors such as starch dextrinization, α‐amylase stability, isomerization of maltodextrins, hydrolysis of sucrose, purity of amyloglucosidase and linearity of the glucose/GOPOD standard curve were evaluated. AOAC Method 996.11 and 2014.10 show similar repeatability and reproducibility, but the former method is easier to use and more robust. A simpler version of AOAC Method 996.11 is introduced.