Effects of drying on the physical and chemical properties of palm kernels
In Malaysia, silo drying is the most common drying practice to reduce the moisture content of palm kernels from 30% to about 7% (dry basis). Long drying hour, high energy consumption, lack of a systematic drying procedure, and lack of proper study are some of the palm industry challenges. Plus, N...
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| 主要作者: | |
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| 格式: | Thesis |
| 語言: | English |
| 出版: |
2019
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| 主題: | |
| 在線閱讀: | http://psasir.upm.edu.my/id/eprint/89901/1/FK%202020%2021%20ir.pdf |
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| 總結: | In Malaysia, silo drying is the most common drying practice to reduce the moisture
content of palm kernels from 30% to about 7% (dry basis). Long drying hour, high
energy consumption, lack of a systematic drying procedure, and lack of proper study are
some of the palm industry challenges. Plus, Non-homogenous drying, lack of a
systematic drying procedure, variation in air velocity and temperature reduce the palm
kernel drying efficiency. Computer simulation has been used in the drying process to
develop information which could be utilized to improve, modify, design or evaluate the
drying system. For simulation purpose, data on physical properties, equilibrium moisture
content and thin layer drying characteristics of palm kernel are required. Thus, the first
objective of this study was to investigate the properties of palm kernel. Selected physical
properties of palm kernel were studied as a function of moisture content in the range of
2-31%. The equilibrium moisture content of palm kernels was determined by static
gravimetric method and modified Oswin model was selected as the best-fitted equation.
Moreover, thin layer drying characteristics of palm kernel was studied and Henderson &
Pabis model was chosen for simulation purpose. In order to study fixed bed drying of
palm kernel, a semi-pilot scale fixed bed dryer was fabricated. Drying was carried out
with different air temperatures and air velocities. Drying capacity and electricity cost
increased 44.23% and 57% when air velocity changed. Drying significantly (P<0.05)
reduced free fatty acid, colors, and moisture & impurities. However, no peroxide was
detected. Fresh palm kernel had 0.72% free fatty acid which was reduced to 0.32% at
80°C, 3 m/s drying experiment. Saturated fatty acids increased when the moisture
content decreased while unsaturated fatty acids decreased slightly. FTIR result showed
a reduction in O–H stretching, while long chain alkyl and C=O stretching started to
appear. Cellulose/ hemicellulose and lignin compounds were decomposed from palm
kernel while saturated fatty acids were decomposed from palm kernel oil. Drying
promotes membrane rupture and cell wall degradation and therefore oil started to be
detached from the cells. The approach of simulation program was initiated by modifying
an existing computer procedure to meet the purpose of this study. Computer simulation was validated using the fixed bed drying data. There was a relatively good prediction of
the moisture content but, simulation somewhat reduced the drying time by about less
than 1 h. The differences between the experimental and simulated values were under
13% which in drying simulation studies is regarded as a satisfactory agreement. Hence,
this computer simulation may be used to modify the current industrial palm kernel dryer. |
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