Palm Kernel Testa Removal And Its Effects On Extracted Oil Quality
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Date
2016-04
Authors
Wan Sharuddin, Wan Nursyazreen Dalila
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Palm kernel (PK) has surrounded by a thin dark layer brown which is testa. Testa are very difficult to be removed because testa strongly attached to the kernel seed. The presence of testa will affects the color of the oil. So, the testa needs to be removed before extraction process to improve the quality of oil. The physical characteristics of PK before and after the palm kernel testa (PKT) removal process were investigated. PKT was removed from the palm kernels using a method consisting of sequential treatment with sodium carbonate (Na2CO3) followed by hydrogen peroxide (H2O2). Screening and optimization experiments carried out on the testa removal process determined that the optimum parameters were at Na2CO3 concentration (C1) of 23%, Na2CO3 temperature (T1) of 91°C, H2O2 concentration (C2) of 23% and H2O2 temperature (T2) of 86°C at 80 min (t1) and 50 min (t2), respectively. A second-order regression model which was developed fitted the data adequately with an R2 value of 0.9259. Scanning electron microscopy (SEM) images of palm kernel with testa (PKt) and palm kernel without testa (PKw) showed that application of the testa removal process did not result in any major changes in the cellular structure of PK. Total oil yield for PKt and PKw was 48.2% and 47.3%, respectively, indicating that the testa removal process did not result in a drastic alteration of the oil content of PK. Colour measurements carried out on oil extracted from PKt and PKw via Soxhlet extraction with n-hexane determined that colour change between two color occurred about 48.22. The yellowness index (YI) for oil extracted from PKt and PKw was 83.20 and 10.87, respectively, which indicated that the testa removal process resulted in oil with less yellow pigmentation. Gas chromatography-mass spectrometry (GC-MS) results showed that while free fatty acids (FFA) were present in oil from PKt, they were greatly reduced in oil from PKw. Hardness testing was carried out via Instron UTM 5582 to determine the maximum load to rupture the kernel for PKt and PKw was 565.0 N and 148.3 N, respectively. This indicated that PKw was softer compared to PKt.
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Keywords
Testa