Date of Graduation

12-2024

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor/Mentor

Atungulu, Griffiths G.

Committee Member

Rahman, Mahfuzur

Second Committee Member

Hettiarachchy, Navam S.

Third Committee Member

Fernandes, Samuel B.

Keywords

fissure formation; mechanical strength; Milled rice quality; post-harvest management; subfreezing storage; transportation

Abstract

This study comprehensively evaluates the effects of environmental conditions, transportation, and storage practices on the quality of milled rice using three cultivars: CLL16 (long grain pureline), XP753 (long grain hybrid), and Titan (medium grain pureline). Three distinct objectives guided the research: (1) assessing the impact of relative humidity (RH), temperature, and exposure duration on rice quality post-milling and post-storage; (2) analyzing seasonal and locational influences on rice quality during transportation and storage; and (3) investigating the effects of subfreezing storage on key quality attributes.
Under controlled environmental conditions, post-milling exposure (PME) caused significant quality degradation at higher RH (75% and 90%) and prolonged exposure durations. Titan and XP753 exhibited higher sensitivity to humidity, with increased moisture content (MC), higher fissure percentages, and reduced mechanical strength, while CLL16 demonstrated greater resilience. Transportation and seasonal studies across three locations—Texas, Michigan, and California—indicated that fall conditions were most favorable for rice quality, with Michigan showing the best outcomes. Summer in Texas caused significant quality deterioration, with Titan experiencing the highest fissuring and XP753 the largest drop in mechanical strength. Among cultivars, XP753 resisted fissuring best, while Titan displayed superior mechanical strength but greater sensitivity to high-stress conditions. Subfreezing storage conditions (-5°C, -10°C, -15°C) highlighted the resilience of Titan in maintaining mechanical strength and minimizing fissures, whereas CLL16 exhibited better moisture retention, and XP753 showed the highest fissure susceptibility.
Statistical analyses confirmed that RH, temperature, cultivar type, and storage duration significantly influenced rice quality parameters (p < 0.0001). Overall, CLL16 emerged as the most stable cultivar under varying environmental conditions, while Titan showed promising results in subfreezing storage scenarios. The findings underscore the importance of tailored, cultivar-specific strategies for post-harvest management, transportation, and storage. Practical recommendations include optimized humidity control, seasonal adjustments during transit, and leveraging subfreezing storage for preserving rice quality over extended durations. These insights aim to minimize post-harvest losses and ensure premium rice standards in global markets.

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