Date of Award

6-1986

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Human Ecology

Major Professor

Marjorie P. Penfield

Committee Members

Mary Nelle Traylor, Nina L. Marable, Sharon L. Melton, Vernon H. Reich

Abstract

Functional properties of Thual hull-less whole-grain barley flours milled from barley grown in two locations were studied. Proximate composition of Tennessee-produced barley flour approximated that of whole-wheat flour; flour milled from Alaska-produced barley had reduced protein and increased carbohydrate plus ash levels. Alaska barley flour had higher levels of the amino acids detrimental to loaf volume, whereas higher levels of amino acids related to increased loaf volume were present in the Tennessee barley flour. Photomicrographs of flour components revealed a bimodal starch distribution. Starch granule shapes approximated those of wheat. Adhering matter was present.

Composite flours that were 50% bread and varying levels of whole-wheat to whole-grain barley (50:0, 40:10, 30:20 and 29:30) were studied in apparent viscosity, dough development and dough expansion systems. Mixogram parameters reflected slow hydration of the barley flour and the quality and quantity of protein present. Salt (1.5, 2.0, 2.5 or 3.0%) increased dough strength at all barley flour levels; salt effect was greater when the composite flours contained the Alaska barley. The positive effect of salt on dough strength was reduced in complete dough systems. Differences in apparent viscosity and dough expansion had no practical importance in bread-making functionality.

Response surfaces from the complete dough development study that depicted barley flour and salt levels within barley source were used to identify an optimal formula for each barley source. Breads containing composite flours were 20% barley flour from grain produced in each location. A 50:50 bread: whole-wheat composite flour was the control. Salt level in all breads was 2.0%. Specific loaf volume was reduced by 5-6% with barley incorporation. Appearance of the crumb and shape of the Tennessee barley and control breads did not differ; Alaska barley bread exhibited tunnels. Instron Texture Profile Analysis revealed no differences among the three breads in hardness, cohesiveness, springiness and chewiness; Alaska barley breads were more gummy. Generally, consumer acceptability of appearance, texture and flavor of the two whole-grain barley breads did not differ from the whole-wheat control.

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