Composition, thermal properties, and processing of nonwaxy, high-amylose, and waxy barley for food products

Barley is underutilized as a food ingredient due to a lack of scientific information about grain quality as related to food products. Therefore, a better understanding of barley's composition, thermal behavior and functionality can lead to greater utilization of this valuable grain as a human food. This dissertation covers three areas of investigation: "Structure and Functionality of Barley Starches," "Composition, Microstructure; Water Imbibition and Thermal Properties of Abraded Barley," and "Quality of Flours from Waxy and Nonwaxy Barley for Production of Baked Goods.";Amylose contents of prime starches from nonwaxy and high-amylose barley determined by colorimetric method were 24.6% and 48.7%, respectively, while the waxy starch showed only a trace of amylose. The isoamylase debranched amylopectin showed that waxy starch had a significantly higher percentage of chains shorter than DP 15. The x-ray diffraction pattern and the DSC thermograms of waxy starch differed from nonwaxy and high-amylose. Waxy starch had one transition peak around 60°C, while nonwaxy and high amylose had two peaks around 60°C and around 100°C.;Independent of type of barley, abraded kernels contained less ash, free lipids and protein, but more starch and beta-glucans than whole seeds. At the same abrasion level, waxy barley kernels were softer than nonwaxy barley. Composition, microstructure, water imbibition and hardness of cooked barley kernels were affected in a similar manner by laboratory and commercial abrasion, thus the laboratory process can be used as a tool to predict behavior of barley abraded on a commercial scale.;Waxy barley milled with a Miag Multomat roller mill produced more break flour than nonwaxy barley. Independent of type, abrasion increased flour yield, and changed chemical composition and physical properties of resulting milling fractions. Cookies prepared from waxy were smaller than cookies from nonwaxy barley. In both types of barley, break flour produced larger cookies than reduction flour. Replacement of 20% of wheat flour by barley flour or bran did not significantly affect loaf volume or crumb structure, but decreased hardness of quick bread.