Deep eutectic solvents are emerging green solvents that have potential in many separation processes. This study investigates the performance of choline‐based deep eutectic solvents in the extraction of tocopherols and tocotrienols (collectively known as tocols) from palm oil, a major natural source of tocols. Deep eutectic solvents comprised of choline chloride salt and selected carboxylic acids as hydrogen bond donors were prepared and used in the extraction of tocols from crude palm oil by liquid–liquid extraction. Tocols concentration in the extracted product was at least double that in the control (8671 mg/kg compared to 3285 mg/kg, respectively). Increasing the amount of the deep eutectic solvents increased the tocols concentration in the extracted product up to 18,525 mg/kg, but the yields lowered from 4 % to less than 1 %. The tocols profile was significantly improved by the increase of the tocotrienols fraction in the products from 80.8 to 99.8 %. This study showed that unique interaction between the selected deep eutectic solvents with the tocols make it possible to selectively separate individual tocols in palm oil, where products with fractions rich in tocotrienols and low in tocopherols (particularly α‐tocopherol) are favorable.

Abstract:The conventional separation system for the recovery of palm kernel from its palm shell-kernel mixture using water as process media generates a considerable amount of waste effluent that harms the environment. The aim of this study is to develop a dry separation process for the recovery of palm kernel by using winnowing columns. A commercial system consisting of a series of five winnowing columns was developed and installed at a local palm oil mill. The system parameters, including column height, blower capacity, airflow rate and mesh screen size for shell removal, were studied and optimized to ensure good separation of kernel and shell in the column to enable collection of different sizes of kernel and shell at each column outlet. The performance of the separation process was evaluated in terms of its kernel losses, dirt content and kernel recovery rate. The average kernel losses based on oil palm fresh fruit bunches processed were found to vary from 0.11 to 0.30 wt %, with most of the values obtained being below the targeted limit of 0.30 wt %. The dirt content was in the range 4.56-6.03 wt %, which was mostly below the targeted limit of 5.5 wt %. The kernel recovery rate was in the range 5.69-6.89 wt %, with most of the values achieving the minimum targeted limit of 6.00 wt %. The system operates under completely dry conditions and, therefore, produces zero waste effluent.

Conventional palm oil mill practice not only processes unwanted empty bunches in sterilisation stage but also produces large amount of wastewater. The oil extraction rate (OER) of the mill is affected by the quality of the oil palm fresh fruit bunches (FFB), which may consist of unripe fruit with less oil content, and uneven distribution of steam throughout the bunches during sterilisation. Besides the FFB, oil palm mills also process loose fruits either collected from the plantations or detached during FFB transportation to the mills.As these loose fruitlets are void of the stalk and core of the bunch, processing them in the same way as FFB is not cost effective. The objective of this study was to carry out processing of fruitlets using microwave, followed by solvent extraction. Loose fruitlets detached in plantations usually come from the outer layer of bunch which contains more oil compared to the inner layer. The following methodology was adopted in this study: 1) optimisation of load per batch for microwave processing of fruitlets, 2) optimisation of microwave heating parameters, and 3) processing of fruitlets detached from the same bunch over 21 days. Fruitlets were sterilised via microwave (2.4 GHz, 900 W, medium power) and its oil is extracted by n-hexane. Optimum load of 170-220 g fruitlets per batch with 3 min heating left the fruitlets to be well conditioned, i.e., softened mesocarp and unburned kernel. The fruitlets get heated rapidly by microwave due to instantaneous dielectric heating effect of moisturised materials. Quality of oil extracted from fruits detached from the same bunch collected over 21 days was investigated. Free fatty acids (FFA), deterioration of bleachability index (DOBI), and oxidative stability of the oil was found to have reduced from 1. 3%, 4.32 and 15.18 hr to 6.5%, 0.86 and 5.28 hr, respectively.

In this paper we examined the potential for choline-based deep eutectic solvents (DESs) for selective extraction of tocol isomers from crude palm oil (CPO) through liquid-liquid extraction. The effect of increasing DES amount on the distribution and selectivity of tocol isomers (α-tocopherol, α-β, γ-, and δ-tocotrienol) were investigated. It was found that tocol isomers are distributed in the order of the hydrophilic power of the tocols, with more tocols of higher polarity distributed more into the stripping phase compared to the less polar tocols. Distribution coefficients for α-tocopherol, α-β, γ-, and δ-tocotrienol were 7.8, 13.1, 19.8, 22.1 and 29.6, respectively, when equal weight of CPO and choline chloride-malonic acid eutectic mixture (DES1) was used. With increasing DES1, the distribution of each tocol isomers also increased, due to the increasing polarity of the stripping phase that attracted more tocols. Selectivity of δ-tocotrienol which is the most polar, were always higher than other isomers (α-tocopherol: 3.81, α-tocotrienol: 2.22, β-tocotrienol: 1.50, γ-tocotrienol: 1.34). This confirmed the role of hydrophilic power of the tocols in selective separation of tocol isomers using DES in this study