Date of Graduation

5-2017

Document Type

Thesis

Degree Name

Master of Science in Biological Engineering (MSBE)

Degree Level

Graduate

Department

Biological and Agricultural Engineering

Advisor/Mentor

Sadaka, Sammy S.

Committee Member

Costello, Thomas A.

Second Committee Member

Atungulu, Griffiths G.

Keywords

Biological sciences; Applied sciences; Corn; Grains; Postharvest; Pressure sensors; Respiration; Spoilage

Abstract

High respiration rate of a grain indicates faster degradation of its dry matter. Proper grain management requires chronological and precise measurements of carbon dioxide evolved from grain respiration during the postharvest storage duration. Therefore the main goal of this research was to develop a new technique that evaluates temporal corn respiration rate using pressure sensors. It was based on measuring pressure drop associated with the grain respiration in a closed container and using it to calculate the grain respiration rates.

Dry corn (Zea Mays L.) was procured from a local farmer and stored at 4ºC. Corn rewetting technique was applied A set of eighteen pressure sensor modules were used throughout the course of this study. These modules determine gas productivity for various biological cultures through measuring and recording the cumulative pressure as well as temperatures. A 150-gram subsample from each moisture level was placed in a glass bottle along with two NaOH vials as well as one silica gel vial. The effects of corn storage temperature (23, 35, and 45oC) and initial moisture content (12.9, 14.8, 17.0, 18.8, and 20.7% w.b) on the cumulative respiration and respiration rate were studied for duration of nine days.

The pressure sensor method was found to be reliable in measuring corn respiration rate as affected by the tested parameters. The highest cumulative respiration of 2.625 g-CO2/kg-corn was observed at the moisture content of 18.8% and the medium temperature level of 35oC after nine days. It was also observed that the respiration rate increased with increases in temperature and peaked out at a temperature of 35°C. Respiration rates reached their maximum values of 0.199, 0.755, 0.987, and 1.147 g-CO2/kg-corn.d under the medium temperature level of 35oC and the moisture contents of 14.8% (5th day), 17.0% (5th day), 18.8% (3rd day), and 20.9% (2nd day), respectively. Additionally, an empirical equation to predict the cumulative respiration of corn as affected by storage temperature, moisture content, and storage duration with an adjusted coefficient of determination value of 0.80. This study recommended that respiration of freshly harvested corn exposed to natural air drying samples should be evaluated.

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