Flaxseed gum from flaxseed hulls: Extraction, fractionation, and characterization
Flaxseed gum from flaxseed hulls: Extraction, fractionation, and characterization
Year: 2012
Authors: Cui, S.W. Wu, Y. Goff, H.D.
Publication Name: Food Hydrocolloids
Publication Details: Volume 28; Pages 275 – 283
Abstract:
Soluble dietary fibre with low viscosity has the potential to deliver acceptable mouthfeel and texture when included in the diet in a significant amount to show health benefits. Soluble flaxseed gum (SFG) was reported to have low viscosity, thus has potential in applications as a fibre fortifier. In the present work, SFG extracted from flaxseed hulls was fractionated into a neutral fraction gum (NFG) and an acidic fraction gum (AFG) using ion exchange chromatography. The protein content in SFG (11.8%) and AFG (8.1%) were completely removed by protease to obtain two more protein-free fractions, SFGnP and AFGnP; NFG contained no protein. The uronic acid content in NFG (1.8%) was mostly eliminated, whereas in AFC increased to 38.7%. NFG consisted of high molecular weight (MW) (1470 kDa) arabinoxylans and exhibited pseudoplastic flow behaviour; whereas AFG was mainly composed of rhamnogalacturonans with a higher MW fraction (1510 kDa) and a lower MW fraction (341 kDa) and showed Newtonian flow behaviour. The ranking of intrinsic viscosities (mL g_1) in decreasing order was SFG (446.0) > NFG (377.5) > AFG (332.5). AFG was expected to have higher chain flexibility for its lower value of Huggins constant (0.16) compared to that of NFG (0.54) and SFG (0.48). In comparison with SFGnP, AFGnP and NFG, SFG and AFG showed better surface activities and emulsifying stabilities due to the presence of protein in both fractions. (Authors abstract)
Flax mucilage (soluble flaxseed gum, SFG) occurs mainly at the outermost layer of hull which releases mucilaginous material (soluble gum) easily when soaked in water. Investigating the composition, structure, physicochemical and rheological properties of SFG from hulls will assist in exploring its potential for the food industry. In this current study, the gum (SFG) extracted from flaxseed hulls was further separated into neutral (NFG) and acidic (AFG) fraction gums using ion exchange chromatography (IEC). The chemical (neutral monosaccharide composition, uronic acid and protein content), physical (molecularweight distribution and heat stability), rheological (viscosity, viscoelasticity, intrinsic viscosity and critical concentration,) and functional (surface tension and emulsification) characteristics of SFG and its two fractions are reported.
Soluble flaxseed gum was extracted from hulls before separating the gum extracts into neutral and acidic fractions. Soluble dietary fibre with low viscosity has the potential to deliver acceptable mouthfeel and texture when included in the diet in a significant amount to show health benefits. Soluble flaxseed gum (SFG) was reported to have low viscosity, thus has potential in applications as a fibre fortifier. In comparison to locust bean gum, guar gum and xanthan gum at a concentration of 0.3% (w/v), soluble flaxseed gum exhibited much lower viscosity. Low viscosity � such as that of flax gum � is favoured in the dietary fibre fortification of food, as it does not lead to the problem of �over-texturization� when a significant concentration of fibre is required to show health benefits. The authors noted that the protein content in the soluble flax gums were completely removed by protease to obtain two more protein-free fractions. Only the complete soluble fibre and acidic fibre contained protein, with neutral fibre containing no protein from the beginning. Neutral flaxseed gums consisted of high molecular weight (MW) (1470 kDa) arabinoxylans and exhibited pseudoplastic flow behaviour; whereas acidic flaxseed gum was mainly composed of rhamnogalacturonans with a higher MW fraction (1510 kDa) and a lower MW fraction (341 kDa) and showed Newtonian flow behaviour. In comparison with gums that had no, or removed protein, the full soluble flaxseed gum extract, and the initial acidified fractions showed better surface activities and emulsifying stabilities due to the presence of protein in both fractions. (Editors comments)
Flax mucilage (soluble flaxseed gum, SFG) occurs mainly at the outermost layer of hull which releases mucilaginous material (soluble gum) easily when soaked in water. Investigating the composition, structure, physicochemical and rheological properties of SFG from hulls will assist in exploring its potential for the food industry. In this current study, the gum (SFG) extracted from flaxseed hulls was further separated into neutral (NFG) and acidic (AFG) fraction gums using ion exchange chromatography (IEC). The chemical (neutral monosaccharide composition, uronic acid and protein content), physical (molecularweight distribution and heat stability), rheological (viscosity, viscoelasticity, intrinsic viscosity and critical concentration,) and functional (surface tension and emulsification) characteristics of SFG and its two fractions are reported.
Soluble flaxseed gum was extracted from hulls before separating the gum extracts into neutral and acidic fractions. Soluble dietary fibre with low viscosity has the potential to deliver acceptable mouthfeel and texture when included in the diet in a significant amount to show health benefits. Soluble flaxseed gum (SFG) was reported to have low viscosity, thus has potential in applications as a fibre fortifier. In comparison to locust bean gum, guar gum and xanthan gum at a concentration of 0.3% (w/v), soluble flaxseed gum exhibited much lower viscosity. Low viscosity � such as that of flax gum � is favoured in the dietary fibre fortification of food, as it does not lead to the problem of �over-texturization� when a significant concentration of fibre is required to show health benefits. The authors noted that the protein content in the soluble flax gums were completely removed by protease to obtain two more protein-free fractions. Only the complete soluble fibre and acidic fibre contained protein, with neutral fibre containing no protein from the beginning. Neutral flaxseed gums consisted of high molecular weight (MW) (1470 kDa) arabinoxylans and exhibited pseudoplastic flow behaviour; whereas acidic flaxseed gum was mainly composed of rhamnogalacturonans with a higher MW fraction (1510 kDa) and a lower MW fraction (341 kDa) and showed Newtonian flow behaviour. In comparison with gums that had no, or removed protein, the full soluble flaxseed gum extract, and the initial acidified fractions showed better surface activities and emulsifying stabilities due to the presence of protein in both fractions. (Editors comments)
