Date of Graduation

8-2017

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor

Terry J. Siebenmorgen

Committee Member

Andronikos Mauromoustakos

Second Committee Member

Ya-Jane Wang

Keywords

End-use Processing, Fortification, Parboiling, Rice Processing

Abstract

Efforts to deliver essential micronutrients through existing rice fortification methods are challenged by poor consumer acceptance of fortified rice, production costs, and equipment availability. Current research efforts seek to explore the potential of parboiling to improve nutrient delivery. This study investigates factors that affect iron transfer into the kernel endosperm via parboiling by evaluating the impact of varied milling durations, iron concentrations in the soaking water, and parboiling conditions upon iron penetration into the rice kernel. Long-grain rice grown in Arkansas was parboiled as rough, brown, and milled rice under various soaking and steaming temperature conditions. Visual quality of the milled parboiled rice was evaluated using a colorimeter utilizing the L* a* b* color scale. Compositional analyses quantified the impact of parboiling conditions upon the iron content of various rice kernel components.

This work demonstrates that hull and bran layers of the rice kernel act as a barrier to iron uptake via parboiling fortification. Hybrid CL XL745 and pureline Diamond rice cultivars exhibited differences in iron uptake and response to parboiling conditions. Parboiling brown and milled rice resulted in increased fortification efficiency compared to rice parboiled in the rough rice form. Parboiled conditions (soaking temperature and inclusion of a steaming step) were critical determinants of iron penetration into the rice kernel and of parboiled rice color. Milling studies indicated that iron fortificants primarily deposit in the external kernel layers.

Optimization of this fortification method may be particularly advantageous in regions of the world where rice is a staple crop and where it represents a major source of daily caloric intake. Understanding the impacts of parboiling soaking and steaming steps may allow rice processors to deliver increased nutrition via parboiled rice.

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