Date of Graduation

5-2014

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor

Terry J. Siebenmorgen

Committee Member

Ya-Jane Wang

Second Committee Member

Andronikos Mauromoustakos

Keywords

Biological sciences; Applied sciences; Co-mingle; Functional properties; Gelatinization; Milling; Pasting; Rice

Abstract

Differences have been observed in the milling and functional properties of different rice cultivars, particularly between hybrid and pureline cultivars. Co-mingling of rice cultivars commonly occurs during harvest, storage and drying operations. Thus, there is a need to study the effect of co-mingling on the milling and functional properties of rice cultivars. Two long-grain, hybrid (H) cultivars CL XL745 and CL XL729 and two long-grain, pureline (P) cultivars CL 151 and Wells were used to prepare CL XL745/CL 151 (H/P), CL XL745/CL XL729 (H/H) and Wells/CL 151 (P/P) co-mingles, mixed in various proportions. Milled rice yield (MRY), head rice yield (HRY), surface lipid content (SLC), head rice color, head rice chalkiness and gelatinization and pasting properties of head rice flour were measured for individual lot samples, as well as the above mentioned co-mingled samples. Kernel dimensions, total lipid content (TLC), chalkiness and bulk density of brown rice samples of the individual cultivar lots were also studied to determine the effect of brown rice properties of individual cultivar lots on the milling and functional properties of co-mingled samples. The MRYs, HRYs, head rice chalkiness and pasting properties of the co-mingled samples increased or decreased with the increasing percentage of a given cultivar in the co-mingled samples. The differences in head rice whiteness and yellowness of the co-mingled samples milled to the same DOM were negligible, indicating that co-mingling did not affect the color of rice after milling to the same DOM. An investigation of gelatinization curves showed that the co-mingled samples retained characteristics of the gelatinization properties of the individual cultivars used in those co-mingles. For example, the onset gelatinization temperature (To) of a co-mingled sample was equivalent to the To of that cultivar in the co-mingle with the lower To. These findings will help to make key decisions regarding the use of co-mingles depending on the brown rice, milling and functional properties of the individual cultivar lots used for co-mingling.

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