Phytonutrients are plant-derived bioactives which are widely utilized as colorants or supplements in food, cosmetic, and pharmaceutical products. To meet the global demand for phytonutrients, oil palm has emerged as a promising source of phytonutrients on account of its large-scale plantation worldwide and high oil productivity. Phytonutrients including carotenoids, tocols, sterols, squalene, phospholipids, coenzyme Q10, and polyphenols can be found in crude palm oil as well as in the byproducts (e.g. palm oil mill effluent and palm-pressed fiber oil) generated from the palm oil milling process. However, the high viscosity and semisolid properties of palm oil are problematic in phytonutrient extraction. Another major challenge is the retention of the sensitive phytonutrients during the extraction process. Over the years, the advances in the extraction methods have improved the extractability of phytonutrients. The emerging extraction methods can operate under mild conditions to mitigate the risk of phytonutrient degradation. This review outlines the types of phytonutrient in palm oil and their extraction strategies. The working principles and operating conditions of extraction methods are discussed along with their potential and limitations in terms of extraction efficiency and practicability. The methods for pretreatment of feedstocks for improving extraction efficiency are also highlighted. The challenges in the extraction of phytonutrient from palm oil feedstock are summarized. Lastly, we provide suggestions for overcoming the limitations and improving the performances of phytonutrient extraction.
Electrospun polyacrylonitrile (PAN) nanofiber membrane was functionalized with chitosan and proteins for use in the treatment of dye-containing wastewater. The PAN nanofiber membrane was subjected to alkaline hydrolysis, before being grafted with chitosan and subsequently the proteins from chicken egg white. The resultant nanofiber membrane (P-COOH-CS-CEW) was comprehensively characterized using thermogravimetric analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. The efficiency of P-COOH-CS-CEW in removing cationic dye toluidine blue O (TBO) and anionic dye acid orange 7 (AO7) in aqueous solution was evaluated. Based on the performance of model fitting, Langmuir and pseudo-second-order kinetic model could be used to describe the performance of P-COOH-CS-CEW in the removal of TBO (pH 10) and AO7 (pH 2) from the dye solutions. The adsorbed TBO and AO7 dyes can be completely desorbed by an elution solution made of 50% (v/v) ethanol and 1 M sodium chloride. After five consecutive adsorption-desorption cycles, the efficiency of dye removal by P-COOH-CS-CEW was maintained above 97%.