Date of Award
Doctor of Philosophy
Food Science and Human Nutrition
The dominant mutant amylose-extender (Ae1-5180) maize starch is a new starch variety and is derived from spontaneous mutation. Scanning electron microscopy, gel permeation chromatography (GPC), amylose content, amylopectin chain-length, and thermal properties (gelatinization and retrogradation) indicated that the doses (1-3 doses) of the dominant gene did not affect the structure or properties of the starch. GPC and real amylose content of these starches indicated that they contained a large amount of intermediate components (≈20%). The Ae1-5180 dominant mutant starch contained 33% amylose. The amylopectin branch-chain length was shorter than that of the intermediate component. Thermal analysis indicated that the dominant mutant starches were different from the common high amylose maize starch (which were derived from the recessive mutant). The dominant starches had lower gelatinization temperatures than the recessive high amylose starch;Starch contains phosphorus of different chemical structures, such as phospholipids, starch phosphate monoester and inorganic phosphate. The phosphorus in starch affected functional properties. Phospholipids reduced the clarity and pasting viscosity of starch, whereas starch phosphate monoesters increased the clarity and the pasting viscosity of starch. The conventional chemical colorimetric method for determination of phosphorus in starch provided only the total phosphorus contents in starch samples without differentiating chemical structure. P-31 NMR spectroscopy can determine both phosphorus structures and the contents in starch;Characterizing of the starch structures and properties, and the non-starch components provide information for product development. Because of the high price of mung bean noodles, replacing the mung bean starch with other cheaper starch such as tapioca starch would be economically desirable. The fine structures and physical properties of mung bean starch and tapioca starch were determined. Mung bean starch contained more amylose, and the chain-length of amylopectin long-branch-chains were longer than for tapioca starch. Mung bean starch contained phospholipids but tapioca starch did not; mung bean starch contained a higher amounts of starch phosphate monoester than tapioca starch. Mung bean starch gelatinized at higher temperatures;The noodles made from solely cross-linked tapioca starch did not show comparable properties to mung bean noodles; but, a mixture of cross-linked tapioca starch and high-amylose maize starch provided noodles with similar properties to the mung bean starch noodles. The tensile strength, water absorption, solid loss, and sensory properties were measured to compare the quality of the noodles.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Kasemsuwan, Tunyawat, "Characterization and food applications of high amylose and other varieties of starch " (1995). Retrospective Theses and Dissertations. 11434.