Dehulling and Its Effect on Supercritical Extraction of Palm Kernel Oil.

Palm kernel contains 4-5% of a thin brown skin, 0.1-0.2 mm thick called testa. Testa removal prior to the extraction process is effected by treating the kernel with hydrochloric acid. Soaking time, the minimum time required to remove the testa effectively from the kernel decreases with acid concentration and temperature. Soaking time is shortened from 63 minutes to 10 minutes when acid concentrations of 6 M and 12 M at 60°C were used, respectively. The extraction of the dehulled and undehulled ground palm kernel using supercritical carbon dioxide (SC-CO2) as a solvent at a pressure range 20.7 to 48.3 MPa and temperatures between 40-80°C is studied. At 48.3 MPa and 80°C the solubility of the oil is about 20 g/100 g carbon dioxide. The difference in solubility of the oil from the dehulled and undehulled palm kernel is not significant. However, a better quality light colored palm kernel oil with a lower fatty acid content is produced in the extraction of dehulled palm kernel besides a more attractive low fiber content palm kernel meal.