Date of Award
Doctor of Philosophy
Food Science and Human Nutrition
Food Science and Technology
Functionalities of starch for food and non-food applications are dependent on the starch structures and properties, which are affected by both the genetics and the growing conditions of the crop. Objectives of this dissertation research were to 1) Understand the unique properties of Tibetan hull-less barley starches, their structures, and the impacts of growing conditions; and 2) Understand dosage effects of waxy gene on the contents and structures of amylose and amylopectin and properties of corn starch; and 3) Understand the starch physicochemical properties of Apios mother and child tuber and the mechanism of starch development.
Tibetan hull-less barley varieties, BQ and KQ, were grown at two locations with different growing temperatures and rainfall. The BQ starches displayed significantly lower onset-gelatinization temperature, larger gelatinization-temperature range, and higher peak viscosities than the KQ starches. The differences in starch thermal and pasting properties between BQ and KQ starches were attributed to the annealing of starch and enhanced amylose-lipid complex formation, resulting from higher growing temperature and more rainfall during the development of the KQ starches.
Reciprocal crossing of isogenic normal and waxy corn lines was conducted to develop hybrids with different dosages of waxy gene (3, 2, 1, 0) in the endosperm. The amylose content of starch and proportion of extra-long branch-chains negatively correlated with dosages of the waxy gene. The proportion of short chains (DP < 17) positively correlated, whereas that of intermediate chains (DP 17-30) negatively correlated with dosages of the waxy gene. The conclusion gelatinization-temperature and gelatinization temperature-range of the starch were positively correlated with the waxy-gene dosage, indicating that amylose facilitates gelatinization of the surrounding crystallites of amylopectin.
Apios americanais a wild legume bearing edible tubers. Domestication of Apios is in process because of the superior nutritional value of the tuber. The harvested Apios tuber can be planted in the following year as the mother tuber to further grow and produce child tubers.The Apios mother-tuber starch displayed higher degree of crystallinity, greater gelatinization enthalpy-change, longer branch-chain length of amylopectin, and lower pasting viscosity than the counterpart child-tuber starch. The mother-tuber starch of Apios 2127 showed two peaks of gelatinization, which was attributed to two groups of starch granules having different structures and gelatinization temperatures. The group of starch granules with a higher gelatinization-temperature was carried over from the previous year and went through a longer annealing process during the two-year growing of the tuber.These results of this dissertation research demonstrated significant effects of both genetics and the growing conditions on starch structures and properties.
Yangcheng, Hanyu, "Starch structures and properties affected by genetics and by environment" (2016). Graduate Theses and Dissertations. 15205.