Publication no. C-2000-0817-05R |  VIEW ARTICLE

Observations on the alpha-Amylolysis Pattern of Some Waxy Maize Starches from Inbred Line Ia453.

Eric Bertoft (1,2), Charles Boyer (3), Robin Manelius (1), and Ann-Kristin Åvall (1). (1) Department of Biochemistry and Pharmacy, Åbo Akademi University, BioCity, P.O. Box 66, FIN-20521 Turku, Finland. (2) Corresponding author: Fax: +358-2-2154745. E-mail: <eric.bertoft@abo.fi> (3) Oregon State University, Department of Horticulture, Agriculture and Life Science 4017, Corvallis, OR 97331-7304. Cereal Chem. 77(5):657-664. Accepted May 4, 2000. Copyright 2000 American Association of Cereal Chemists, Inc.

Maize starches of the endosperm mutants waxy (wx), dull:waxy (duwx), and amylose-extender:dull:waxy (aeduwx) from inbred line Ia453 lack amylose. However, in addition to high molecular weight (HMW) amylopectin, the duwx and aeduwx starches contained 40 and 80%, respectively, intermediate branched material of low molecular weight (LMW). As gelatinized, the amylopectin of the wx starch was easily hydrolyzed into small dextrins by the alpha-amylase of B. amyloliquefaciens, but components of duwx and aeduwx possessed partial resistance to amylolytic attack. Residual material of intermediate size obtained by a 4-hr alpha-amylolysis could not be separated from LMW dextrins by fractional precipitation in methanol. It is suggested that this material possessed a more regularly branched structure, in which the D-glucosyl chain segments were too short to allow alpha-amylase action. The granular starches of duwx and aeduwx genotypes were initially considerably more resistant than the wx sample to alpha-amylase attack. This was possibly due to an altered structure in the amylopectin component or the high content of intermediate material in the former granules.