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Document Type

Thesis - University Access Only

Award Date

2012

Degree Name

Master of Science (MS)

Department

Health and Nutritional Sciences

First Advisor

Padmanaban G. Krishnan

Abstract

Selenium (Se) is an essential micronutrient for humans. It is the only mineral that qualifies for an FDA-approved qualified health claim for general cancer reduction. A level of 1 ppm of Se in flour has been recommended as a good starting point for food processing efforts. Se-fortified wheat protein concentrates (WPC, gluten) and isolates (WPI) can be used for fortification of weak flours. Our earlier studies determined that up to 77% of the grain Se was retained in the endosperm. Rheological properties of the WPC, WPI and flour blends may reveal the role of Se in gluten functionality. Longitudinal surveys (2004-2010) of South Dakota wheat reveal a wide range of Se (0.33-37.6 μg/g). Samples from two years, 2008 and 2009 were analyzed for grain Se content. The range of grain Se concentrations in year 2008 wheat samples (n=265) were 0.33 μg/g -37.30 μg/g. The range of grain Se concentrations in year 2009 wheat samples (n=75) were 0.81 μg/g -10.20 μg/g. Three composites (high, medium and low Se) wheat were constructed based on grain Se concentration. Wet and dry processing (grinding, aqueous & aqueous-alkaline) extraction schemes yielded wheat fractions with predictable Se content from ground whole wheat. Grain with 3.5, 5.2, and 10.3 ppm Se yielded WPC with Se concentrations of 16.8, 22.6 and 46.1 ppm and WPI of 15.8, 21.2 and 43.8 ppm, respectively. Addition of wheat protein isolates and vital gluten at the 5% substitution rate in flour significantly increased the water absorption of the wheat flour. Addition of wheat protein isolates decreased peak dough mixing time while vital gluten, in general, contributed to increased dough mixing time requirement. However, there was no significant difference in peak mixing time for the blends. Dough stability was significantly higher in vital gluten blends compared to wheat protein isolates blends. Farinograms of flour fortified at the 5% level with high, medium and low Se gluten showed that there were no significant differences in dough development time (p=0.15), Mechanical Tolerance Index (MTI)(p=0.65), and time to breakdown (p=0.10). The high- Se wheat blend, however, had significantly higher water absorption (p=0.004) compared to low and medium Se wheat blends. Dry Gluten content was significantly higher in high- Se wheat blend (p=0.002) while there was no significant difference in gluten-index (p=0.58) between the samples. Fortification with WPC and WPI prepared from high Se wheat holds potential for enhancing the baking efficacy of weaker flours while increasing Se content in the product. Bread was prepared by fortifying normal bread flour with 5% of High Se vital gluten. Se concentration of control bread was 0.23 μg/g whereas; fortified bread had Se concentration of 1.49 μg/g. This value was six fold higher than the control sample. Glutenin content ranged from 41.5-43.3% of total gluten, while Gliadin ranged from 61.7-62.3% of total gluten. Se content ranged from 73.8-80.8% for Gliadin and 90.3- 93.6% for Glutenin when gluten was fractionated.

Library of Congress Subject Headings

Selenium in human nutrition
Flour
Wheat
Enriched foods

Description

Includes bibliographical references (leaves 68-73)

Format

application/pdf

Number of Pages

83

Publisher

South Dakota State University

Rights

In Copyright - Educational Use Permitted
http://rightsstatements.org/vocab/InC-EDU/1.0/

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