Date of Graduation

5-2024

Document Type

Thesis

Degree Name

Bachelor of Science in Agriculture

Degree Level

Undergraduate

Department

Food Science

Advisor/Mentor

Atungulu, Griffiths

Committee Member/Reader

Ubeyitogullari, Ali

Committee Member/Second Reader

Rahman, Mahfuzur

Abstract

Market demand for instant rice--a processed form of rice that is cooked and dehydrated before it is sold--has risen tremendously and become a significant component of the rice industry. Compared to freshly cooked rice, the quality of instant rice (in terms of texture, color, aroma, etc.) is much lower. There exists little information regarding how instant rice’s storage conditions affect its quality. Such information may be elucidated by studying sorption isotherms which describe the storage temperature, relative humidity, and instant rice moisture relationships.

The purpose of this study was to generate moisture sorption isotherms of instant rice for temperatures and relative humidity ranges encountered during instant rice handling and storage. In addition, the study explored changes in physicochemical characteristics of instant rice during prolonged storage of up to one year.

Rough rice samples conditioned to 12.5% moisture content (MC) wet basis were used to make 4 sample types: brown, white (0.4% surface lipid content), parboiled brown, and parboiled white. Samples were cooked and dried to 12% MC wet basis. The vapor sorption analyzer (VSA) was used to determine the moisture sorption isotherms (desorption and adsorption) of dried instant rice held at 25℃ for six months, with relative humidity ranging from 0% to 100%.

To determine the impact of prolonged storage on shelf life, samples of the dried instant rice were securely stored at 20, 25, and 30℃ for a total of 6 months. Stored samples were taken out and tested for quality changes (protein content, texture, and color) every 8 weeks.

Results show that the storage duration and temperature conditions used had minimal impacts on the rice quality parameters tested. However, there were significant changes in quality due to parboiling and between brown and white rice samples. Moisture sorption curves showed that parboiling had little effect on storage behavior of rice samples, but extended storage (6 months) did cause change. Moisture sorption adsorption and desorption curves were shifted up following storage, indicating that storage duration does impact storage behavior.

Ultimately, it is expected that the results from this study will provide foundational knowledge that is crucial for the rice industry to predict storability of instant rice, improve the quality of instant rice, and make the products more competitive.

Keywords

Instant Rice, Rice Storage, Food Processing, Quality of Instant Rice, Post-harvest Rice Processing

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