Improvement of a process for purification of tocopherols and sterols from soybean oil deodorizer distillate

Separation of tocol (tocopherol & tocotrienol) and phytosterols from palm fatty acid distillate by saponification and purification by low temperature solvent crystallization

The tocotrienols (T3) are the vitamin E family members with excellent antioxidant properties and prevent autocatalytic lipid peroxidation. Palm Fatty Acid Distillate (PFAD) is a volatile organic material obtained during palm oil refining and consists of tocol (α-tocopherol/T, α, γ, β, and δ- tocotrienol/T3) up to 0.8% and represents a potential source for recovering these valuable compounds. Various methods have been studied to extract vitamin E; however, only a few are commercially available. To fulfil the need for technology for recovering these minor components, leaching the tocotrienol from solidified PFAD was carried out. In this study, the fatty acid of PFAD was saponified using NaHCO₃/Ca(OH)₂ and extracted the unsaponifiable fraction using solvent. Further, fraction was purified by low temperature solvent based crystallization using hexane at 5 ± 1.0 °C for 24 h and removed sterol. The best determined parameters like reaction time (30 min), the ratio of PFAD to Ca(OH)₂ (1,w/w), reaction temperature (30 °C) and stirring speed 300 rpm were yielded up to 98.6% fatty acid conversion to calcium soap and extraction with hexane obtained higher concentration of tocol (28.1%). The sterol separated from the tocol rich fraction by low temperature solvent crystallization contains up to 37.1% of phytosterol (β-sitosterol) concentration.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-022-05402-7.

Advances in various techniques for isolation and purification of sterols

Plants consist of triterpenoids such as phytosterols (PT) (C₂₉H₅₀O) with steroidal nuclei, including sitosterol, stigmasterol, brassicasterol and campesterol. They are hydrophobic but soluble in alcohol and other organic solvents and are isolated from industrial waste deodorizer distillates of various edible oil industries. They exist as free PT or their ester derivatives in soybean, rice, wheat, oat, cottonseed and corn fiber, and other cereals and grains. Conventional isolation techniques such as solvent extraction, distillation, evaporative fractionation, saponification and chemical esterification are employed for isolation and purification of PT. The present article reviews the various advanced separation techniques like solvent crystallization, supercritical fluid extraction, high speed counter-current chromatography and enzymatic process as strategic methods to isolate and purify sterols.

Vegetable Oil Deodorizer Distillate: A Rich Source of the Natural Bioactive Components

Deodorizer distillates are waste products of edible oil processing industries obtained during deodorization process of vegetable oils. It is very cheap source of several health beneficial components such as tocopherols, sterols, squalene as well as free fatty acids which have numerous industrial applications. These valuable components are being used in different foods, pharmaceutical formulations and cosmetics. Traditional sources of these useful components are vegetable oils, fruits, vegetables and nuts. Global need of these important components has been exceeded than their availability. The deodorizer distillates of various vegetable oils are considered to be a rich source of several valuable components. Present review will cover brief introduction of common processing stages involved in all vegetable oil processing, analytical methods for characterization of deodorizer distillates by instrumental techniques, importance and commercial value of deodorizer distillates. Future prospective of current field may leads to cost efficient processes and increased attention on the nutritional quality of deodorized oil and commercial applications of deodorizer distillates as well as their valuable components.

Improved conventional and microwave-assisted silylation protocols for simultaneous gas chromatographic determination of tocopherols and sterols: Method development and multi-response optimization

This paper reports on improved conventional thermal silylation (CTS) and microwave-assisted silylation (MAS) methods for simultaneous determination of tocopherols and sterols by gas chromatography. Reaction parameters in each of the methods developed were systematically optimized using a full factorial design followed by a central composite design. Initially, experimental conditions for CTS were optimized using a block heater. Further, a rapid MAS was developed and optimized. To understand microwave heating mechanisms, MAS was optimized by two distinct modes of microwave heating: temperature-controlled MAS and power-controlled MAS, using dedicated instruments where reaction temperature and microwave power level were controlled and monitored online. Developed methods: were compared with routine overnight derivatization. On a comprehensive level, while both CTS and MAS were found to be efficient derivatization techniques, MAS significantly reduced the reaction time. The optimal derivatization temperature and time for CTS found to be 55°C and 54min, while it was 87°C and 1.2min for temperature-controlled MAS. Further, a microwave power of 300W and a derivatization time 0.5min found to be optimal for power-controlled MAS. The use of an appropriate derivatization solvent, such as pyridine, was found to be critical for the successful determination. Catalysts, like potassium acetate and 4-dimethylaminopyridine, enhanced the efficiency slightly. The developed methods showed excellent analytical performance in terms of linearity, accuracy and precision.

Novel simple process for tocopherols selective recovery from vegetable oils by adsorption and desorption with an anion-exchange resin

A novel and simple low-temperature process was used to recover tocopherols from a deodorizer distillate, which is a by-product of edible oil refining. The process consists of three operations: the esterification of free fatty acids with a cation-exchange resin catalyst, the adsorption of tocopherols onto an anion-exchange resin, and tocopherol desorption from the resin. No degradation of tocopherols occurred during these processes. In the tocopherol-rich fraction, no impurities such as sterols or glycerides were present. These impurities are commonly found in the product of the conventional process. This novel process improves the overall recovery ratio and the mass fraction of the product (75.9% and 51.0wt%) compared with those in the conventional process (50% and 35wt%).

Methods for obtaining and determination of squalene from natural sources

Squalene is a natural dehydrotriterpenic hydrocarbon (C30H50) with six double bonds, known as an intermediate in the biosynthesis of phytosterol or cholesterol in plants or animals. We have briefly reviewed the natural sources for squalene and focused on the main methods and techniques to obtain and to determine it. Some of its applications in different fields of human activity are also mentioned.

Synthesis and theoretical study of molecularly imprinted nanospheres for recognition of tocopherols

Molecular imprinting is a technology that facilitates the production of artificial receptors toward compounds of interest. The molecularly imprinted polymers act as artificial antibodies, artificial receptors, or artificial enzymes with the added benefit over their biological counterparts of being highly durable. In this study, we prepared molecularly imprinted polymers for the purpose of binding specifically to tocopherol (vitamin E) and its derivative, tocopherol acetate. Binding of the imprinted polymers to the template was found to be two times greater than that of the control, non-imprinted polymers, when using only 10 mg of polymers. Optimization of the rebinding solvent indicated that ethanol-water at a molar ratio of 6:4 (v/v) was the best solvent system as it enhanced the rebinding performance of the imprinted polymers toward both tocopherol and tocopherol acetate with a binding capacity of approximately 2 mg/g of polymer. Furthermore, imprinted nanospheres against tocopherol was successfully prepared by precipitation polymerization with ethanol-water at a molar ratio of 8:2 (v/v) as the optimal rebinding solvent. Computer simulation was also performed to provide mechanistic insights on the binding mode of template-monomer complexes. Such polymers show high potential for industrial and medical applications, particularly for selective separation of tocopherol and derivatives.

Phytosterols: applications and recovery methods

Phytosterols, or plant sterols, are compounds that occur naturally and bear close structural resemblance to cholesterol, but have different side-chain configurations. Phytosterols are relevant in pharmaceuticals (production of therapeutic steroids), nutrition (anti-cholesterol additives in functional foods, anti-cancer properties), and cosmetics (creams, lipstick). Phytosterols can be obtained from vegetable oils or from industrial wastes, which gives an added value to the latter. Considerable efforts have been recently dedicated to the development of efficient processes for phytosterol isolation from natural sources. The present work aims to summarize information on the applications of phytosterols and to review recent approaches, mainly from the industry, for the large-scale recovery of phytosterols.