Influence of different extraction techniques on recovery, purity, antioxidant activities, and microstructure of flaxseed gum

Abstract

Four extraction techniques (that is, hot water extraction [HWE], alkaline-acidic extraction [AAE], ultrasound assisted extraction [UAE], and microwave assisted extraction [MAE]) were compared for flaxseed gum extraction and their influence on the yield, purity, structural characterization (monosaccharide composition, molecular weight distribution, and microstructure by transmission electron microscope), and antioxidant activity (in terms of scavenging ability of 2,2diphenyl-1-picrylhydrazyl [DPPH], 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid [ABTS], and reducing power) was investigated. The HWE achieved higher yield (8.96%) than UAE (7.84%) followed by MAE (7.01%) and AAE (6.44%). Moreover, the four flaxseed gum (FSG) samples exhibited the identical monosaccharide composition, but slight difference was observed in the content, whereas the molecular weight ratios exhibited significant difference. All samples displayed concentration-dependent manner for all antioxidant assays. UAE-FSG showed significant higher scavenging ability on DPPH free radical, ABTS free radical, reducing power, and β-carotene bleaching assay followed by HWE-FSG, MAE-FSG, and AAE-FSG. Overall results showed that UAE was favorable to the purity of FSG, whereas HWE was more advantageous to improve the extraction yield and facile as it requires no special equipment.

Structural Characterization and Functional Properties of Flaxseed Hydrocolloids and Their Application

“…In addition to the functional properties, FG also shows several biological activities. FG possesses strong antioxidant activity, which has been confirmed in several studies [ 24 , 29 , 30 , 31 , 66 ]. The antioxidant activity of FG is significantly affected by the presence of some phenolic compounds easily extractable with FG, such as caffeic acid, p-coumaric acid, epicatechin, ellagic, cinnamic, and vanillic acids.…”

“…Polysaccharides are easily extractable from flaxseed; it is possible to obtain them from whole seeds [ 41 ], seed hulls [ 43 ], or oilseed cake [ 27 ]. Safdar et al [ 30 ] used four methods for the extraction of FG from whole flaxseeds with differences in the relative yield of FG from flaxseeds: hot water extraction (9.0%), ultrasound-assisted extraction (7.8%), microwave-assisted extraction (7.0%) and alkaline–acidic extraction (6.4%). For the highest yield of FG, hot water extraction is preferable, whereas, for maximal purity, it is most suitable the ultrasound-assisted extraction method.…”

“…Other functional properties of flaxseed gum are represented by its water- and oil-binding capacity [ 3 , 27 ], thickening, stabilizing [ 25 ], and gelling activities [ 28 ]. Due to its form of dietary fiber and presence of phenolic compounds, FG possesses antioxidants [ 24 , 29 , 30 , 31 ], anti-obesity [ 32 ], anti-cholesterol, and anti-diabetic activities [ 33 ].…”

A Review of Extraction Techniques and Food Applications of Flaxseed Mucilage

“…In addition, a significant reduction in the water absorption capacity and emulsifying activity index of FG has been observed with increased extraction temperature. In another study, hot-water extraction (HWE) was shown to be more advantageous than others (ultrasound-assisted extraction (UAE), alkaline–acidic extraction (AAE), and microwave-assisted extraction (MAE)) to improve the extraction yield of FG [ 20 ].…”

“…The ultrasonic treatment exerted a limited impact on monosaccharide composition and protein content. Safdar et al [ 20 ] showed that UAE was favorable to the purity of FG. UAE-FG showed a significantly higher scavenging ability in terms of 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS) free radicals, 2,2′-diphenyl-1-picrylhydrazyl (DPPH) free radicals, reducing power, and the β-carotene bleaching assay than HWE-FG, MAE-FG, and AAE-FG.…”