Cereal Chem 61:527 - 531. | VIEW
Intercultivar Variations in Lipid Content, Composition, and Distribution and Their Relation to Baking Quality.
U. Zawistowska, F. Bekes, and W. Bushuk. Copyright 1984 by the American Association of Cereal Chemists, Inc.
Lipid content and composition of flours and the distribution of dry matter, protein, and lipids in Osborne protein fractions of five hard red spring wheat cultivars with diverse baking quality were investigated. The hexane-soluble lipid (free-lipid) content but not the total lipid content of the flours showed marked differences among the cultivars. Applying prediction equations developed earlier resulted in excellent agreement between measured and predicted loaf volumes using the ratio of nonpolar to polar lipids in the free-lipid fraction. For the five cultivars, the albumin/globulin Osborne fraction contained 21.8-30.3% respectively. The gliadin fraction contained relatively more polar lipid than did the glutenin fraction. For the five cultivars, the lipid content of both fractions was significantly correlated with loaf volume, which indicated that the lipid binding capacity of the gluten proteins, gliadin and glutenin, is an important factor in the breadmaking quality of flour. AUC (0.1M acetic acid, 3M urea, and 0.01M cetyltrimethylammonium bromide)- and acetic acid-soluble fractions of glutenin had the same lipid binding capacity. Determination of the lipid content and composition of three fractions (I, less than 200,000; IIa, 27,500-75,000; and IIIa, 15,500-21,000) of Osborne gliadin fractionated by gel filtration on Sephadex G-200 showed that fraction I had an extremely high binding capacity for polar lipid. Only trace amounts of lipids were associated with the other fractions. Protein composition of fraction I (by SDS-PAGE) showed that it contained mostly the high-molecular weight gliadin componnents (more than 68,000) and small amounts of low-molecular weight components. For the five cultivars, the amount of aggregated fraction 1 was negatively correlated with the remix loaf volume. PAGE electrophoregrams of the gliadin fractions extracted directly from flour by 70% aqueous ethanol showed that the same gliadin components were involved in binding the lipids for the five cultivars. The intensity of some of the bands in the electrophoregram depended on whether lipids were in the starting material.