Study of artificial aging by drying of high moisture rough rice under high humidity conditions | |
| Author | Pornlada Nakakete |
| Call Number | AIT Thesis no.PH-00-20 |
| Subject(s) | Rice--Aging Rice--Quality Rice--Drying |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering |
| Publisher | Asian Institute of Technology |
| Abstract | The effects of natural aging on rice qualities keeping its temperature at 30 ° C and 13 % moisture content -were studied. Rice qualities such as -head rice yields, whiteness, b-value, water absorption and hardness was investigated. It was found out that head rice yield increase with storage time although· insignificantly at 0-5 months storage while whiteness decreased significantly. Water absorption and hardness also increased significantly. Studies also were done to investigate the effects of drying the milled rice at different drying conditions. Drying conditions at different drying temperatures (60, 70, 80 ° C) and at different levels of relative humidity (20,40,60,70, 75 %) of drying air were assessed. The effects of these conditions on the qualities -of milled ·rice were then evaluated. It was concluded that head rice yields decreased when dried at high temperature but low relative humidity but increased significantly when dried at high temperature and high humidity. The b-value also increased when dried at high temperature and high humidity but unchanged at high temperature and low relative humidity. Whiteness also showed similar results to b-value but in the opposite trend. It was also found out that water absorption and hardness of milled rice increased significantly with the combination of increase in drying temperature and high relative humidity. A comparison has then been made on the dried milled rice at different temperature and relative humidity in reference to the naturally aged rice. The comparison between rice yields, b-value, water absorption, whiteness and hardness had been evaluated and compared to that of the naturally aged rice. From the overall results, an optimum conditions of drying air at specific temperatures and relative humidity which is comparable to 5-month old stored rice has been selected. From the overall results it was found out that rice qualities (head rice yields, whiteness? b..,value, hardness) were optimum at 70 °c at 75 % RH and at 80 °c at 70 % RH. This study also has presented non-linear regression models for accelerated aging development at high humidity of heated air. In the models the effects of the different drying conditions on the different rice qualities were analyzed. Using regression analyses, non-linear regression models at a function of storage time, drying temperature and relative humidity were presented for head rice yield, b-value, whiteness, water absorption and hardness. It also had evaluated the performance of the prototype dryer and evaluated the rice quality from a few selected operating conditions. |
| Year | 2000 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Postharvest and Food Process Engineering (PH) |
| Chairperson(s) | Athapol Noomhorm; |
| Examination Committee(s) | Jindal, V. K. ;Rakshit, S. K.; |
| Degree | Thesis (M.Eng.) - Asian Institute of Technology, 2000 |