Date of Graduation

5-2016

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

Bluhm, Burton H.

Second Committee Member

Gibson, Kristen E.

Keywords

Biological sciences; Color; Corn; Drying and tempering; Infrared heating; Moisture removal; Mold load reduction

Abstract

Infrared (IR) heating of corn followed by tempering treatments has potential to rapidly dry and simultaneously decontaminate corn without adverse effect on the overall quality. However, it is vital to determine the optimal processing parameters that maximize throughput and minimize drying energy without affecting overall corn quality. This study investigated the effects of IR heating and tempering treatments on moisture removal, mold load reduction, corn color change, and drying energy requirements. In addition, the study evaluated the feasibility of scaling up IR drying process using a newly built, pilot scale IR dryer. Freshly harvested corn with initial moisture content (IMC) of 20%, 24% and 28% wet basis (w.b.) were dried using a laboratory scale IR batch dryer in one- and two- drying passes. The dried sample were then tempered for 2, 4, and 6 h at 50°C, 70°C, and 90°C. The result showed that as tempering temperature and tempering duration increased, moisture removed increased and was higher for one-pass treatments compared to two-pass; similar trends were observed for mold load reductions. For the studied range of processing conditions, mold load reduction ranged from 1 to 3.8 log CFU/g for one-pass and 0.8 to 4.4 log CFU/g for two-pass treatments. Scaled up IR drying treatments of corn at IMC of 24% w.b. with IR intensity of 2.39, 3.78 and 5.55 kW/m² required only 650 s, 455 s, and 395 s to dry corn down to a safe moisture content (MC) of 13% (w.b.); the corresponding mold load reduction ranged from 2.4 to 2.8 log CFU/g, 2.9 to 3.1 log CFU/g, and 2.8 to 2.9 log CFU/g as intensity increased (p>0.05). This work showed that IR drying of corn holds promise as a rapid drying method with potential benefits of microbial decontamination of corn; this may help producers combat mold related problems such as mycotoxin contamination.

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