A review on newer techniques in extraction of oleaginous flaxseed constituents

Abstract

Flaxseed is the chief oilseed crop that is grown in many regions of the world for medicinal and nutritional purposes. It has been used for oil and fiber since centuries. Flaxseed has an enormous role in functional foods for its nutritional and pharmaceutical values. Among the various components of flaxseed lignans, phenolic acids, proteins and oil are of the main interest. Oil and lignans have prime concentrations in the flaxseed. To study the extraction of these compounds, various extraction methods have been investigated. Oil has been extracted by mechanical pressing in ancient times but presently new techniques have been developed. These include microwave assisted extraction, supercritical CO2 extraction, ultrasonic assisted extraction, etc. Enzymes are also gaining importance in the extraction of oil, lignan and proteins as they give more yield of compounds and easily degrade the cell wall of the flaxseed. The need of these novel techniques lies in the fact that traditional methods have different shortcomings like low yield, more time, more energy and less environmental friendly. This review put on a view to different techniques which have been investigated for the extraction of different components of flaxseed. Quality evaluation and comparison of flaxseed oils and other bioactive components obtained by newer techniques with those produced by conventional extraction methods is also reported.

Flaxseed oil: Extraction, health benefits and products

“…Although the mechanical pressing method is quite popular for flaxseed oil processing, a drawback of this technique is the low extraction recovery of the oil. To improve the yield of extracted oil, many new extraction methods, for example, ultrasound-assisted extraction, microwaveassisted extraction, supercritical CO 2 extraction, subcritical extraction, three-phase partitioning, enzyme-assisted three-phase partitioning etc., have been developed (Kulkarni et al, 2017;Ren et al, 2015;Rombaut et al, 2017;Piva et al, 2018;Sharma et al, 2019;Suri et al, 2020;Szydlowska-Czerniak et al, 2020;Tan et al, 2016).…”

“…Three-phase partitioning process has been developed to extract flaxseed oil, which is usually performed through adding salt and t-butanol to aqueous extracts (Kulkarni et al, 2017;Sharma et al, 2019). Tan et al (2016) utilized enzyme-assisted three-phase partitioning method to extract flaxseed oil, and showed that the yield of flaxseed oil could reach up to 71.68% under the optimized conditions.…”

“…Supercritical carbon dioxide (SC-CO 2 ) is very suitable for the extraction of heat sensitive and fat-soluble compounds (Dabrowski et al, 2019;Sharma et al, 2019). Kulkarni et al (2017) reported oil yield from SC-CO 2 was 30.03%.…”

“…At present, the most common methods to extract flaxseed oil are mechanical pressing and solvent extraction (Sharma et al, 2019;Shim et al, 2015). Fresh unrefined oil from pressing flaxseed has a nutty flavor and the colour varying from yellow to orange.…”

“…High extraction temperature can improve the yield of the mucilage in contrast with cold water extraction (Kajla et al, 2015). However, the wet extraction process is not a good choice for removing the hull of flaxseed because it has too many operation sequences (Sharma et al, 2019;Piva et al, 2017). Therefore, other dehulling methods need to be developed.…”