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A Study of Maize Endosperm Hardness in Relation to Amylose Content and Susceptibility to Damage

November 1997 Volume 74 Number 6
Pages 776 — 780
M. A. Dombrink-Kurtzman 1 , 2 and C. A. Knutson 1

Research chemists, Mycotoxin and Biomaterials Processing Research Units, National Center for Agricultural Utilization Research, Agricultural Research Service, U. S. Department of Agriculture, 1815 N. University St., Peoria, IL 61604. Mention of trademark or proprietary products does not constitute a guarantee or warranty by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that may also be suitable. Corresponding author. E-mail: dombrink@mail.ncaur.usda.gov Phone: 309/681-6254. Fax: 309/681-6686.


Go to Article:
http://dx.doi.org/10.1094/CCHEM.1997.74.6.776
Accepted August 5, 1997.
ABSTRACT

The relative amounts of amylose and amylopectin in maize starch were determined in samples representing hard and soft endosperm. Although differences were small, amylose content differed significantly (P < 0.001 and P < 0.05) between the two types of endosperm, with hard endosperm containing a higher percentage of amylose. Scanning electron microscopy was used to determine that the surface appearance of starch granules from hard and soft endosperm differed. Starch granules from soft endosperm had randomly distributed pores on their surfaces, which had a rough appearance. Few pores were observed on granules from hard endosperm. A fairly common occurrence with starch granules from soft endosperm was the development of wrinkles or fissures upon prolonged exposure to the beam of the electron microscope. Thus, a correlation existed between endosperm hardness, amylose content, and susceptibility to wrinkling and fissures. The granules of the soft endosperm of maize, presumably less mature than the granules of the hard endosperm, have a lower amylose content (20.5 ± 1.9% vs. 23.0 ± 1.0%), exhibit more surface pores, and are more susceptible to wrinkling in an electron beam, compared with granules of the hard endosperm. Results suggested that the composition and internal architecture of the starch granule differ depending on the hardness of the endosperm from which it was obtained.


This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. American Association of Cereal Chemists, Inc., 1997.