Enrichment of carotene from palm oil by organic solvent nanofiltration

Abstract

Palm oil is one of the richest sources of natural plant carotene with typical concentration of about 0.5–0.7 g/L. Unfortunately, during physical refining of palm oil, most of the carotenes were destroyed by high temperatures and this represents a loss of potential source of natural carotene. Various techniques have been developed to extract and recover carotenes from palm oil, however these processes often require high energy usage, and usually renders the oil useless for further consumption. Recently, organic solvent nanofiltration (OSN) has become an important method for molecular separation particularly for the separation of low molecular weight bioactive compounds. This work presents the application of OSN membranes for the separation of carotene from a crude palm oil/solvent system. Several commercial OSN membranes (DuraMem and PuraMem series) fabricated from polyimide were evaluated for their separation abilities. PuraMem 280 showed the best selectivity performance, with the concentration of carotene in permeate oil increased from 0.60 to 0.79 g/L when hexane was used as the solvent. Runs by using DuraMem 150, DuraMem 300 and DuraMem 500 showed low or no selectivity between carotene and triglyceride in all solvents. It was found that the rejection of carotene depends strongly on the type of solvents. A coupled solution diffusion and film theory was also utilized to model carotene transport through OSN membrane. It was demonstrated that OSN can serve as an alternative for the direct carotene recovery from palm oil and can be potentially applied for other minor compounds recovery from vegetable oils.