title: Enzymatic method for measuring starch gelatinization in dry products in situ.
abstract: An enzymatic method based on hydrolysis of starch by amyloglucosidase and measurement of d-glucose released by glucose oxidase-peroxidase was developed to measure both gelatinized starch and hydrolyzable starch in situ of dried starchy products. Efforts focused on the development of sample handling steps (particle size reduction of dry samples followed by a unique mechanical resolubilization step) prior to the enzymatic hydrolysis using native and fully gelatinized flours of corn and rice. The new steps, when optimized, were able to maximize resolubilization of gelatinized/retrograded starch while minimizing solubilization of native starch in dried samples, thus effectively addressing issues of insusceptibility of retrograded starch and susceptibility of native starch to enzymatic attacks and eliminating the need to isolate starch from dry samples before using an enzymatic method. Various factors affecting these and other steps were also investigated, with the objectives to simplify the procedures and reduce errors. Results are expressed as the percentage of the total starch content. The proposed method, verified by measuring mixed samples of native and fully gelatinized flours of five grain species (corn, rice, barley, oat, and wheat) at different ratios, is simple, accurate, and reliable, with a relative standard deviation of less than 5%.
authors.affiliation: Grain Chemistry and Utilization Laboratory, National Small Grains and Potato Germplasm Research Unit, United States Department of Agriculture, Agricultural Research Service-USDA-ARS, 1691 South 2700 West, Aberdeen, Idaho 83210, USA. Keshun.Liu@ars.usda.gov
authors.forename: KeShun
authors.initials: K
authors.lastname: Liu
authors.forename: Jianchun
authors.initials: J
authors.lastname: Han
mesh_terms: D018554:Avena / Q000737:chemistry; D005433:Flour / Q000032:analysis; D005782:Gels / Q000378:metabolism; D005087:Glucan 1,4-alpha-Glucosidase / Q000378:metabolism*; D005947:Glucose / Q000378:metabolism*; D005949:Glucose Oxidase / Q000378:metabolism*; D001467:Hordeum / Q000737:chemistry; D006868:Hydrolysis; D012275:Oryza / Q000737:chemistry; D009195:Peroxidase / Q000378:metabolism*; D012639:Seeds / Q000737:chemistry; D012995:Solubility; D013213:Starch / Q000378:metabolism*; D014908:Triticum / Q000737:chemistry; D003313:Zea mays / Q000737:chemistry
chemical_list: D005782:Gels; D013213:Starch; D005949:Glucose Oxidase; D009195:Peroxidase; D005087:Glucan 1,4-alpha-Glucosidase; D005947:Glucose