Compositional changes during commercial processing of flaxseed

Abstract Compositional changes occurring during processing of flaxseed are of primary importance in adding value to flaxseed products. The physicochemical characteristics of flaxseed products at four stages of commercial processing, cleaning, flaking, pressing and solvent extraction, were determined to improve the functional properties of flaxseed products. The effect of industrial oil extraction on proximate composition, protein extractability, gel electrophoretic profiles, in vitro protein digestibility and viscosity of eight flaxseed products was assessed. The processes of flaking, heating, solvent extraction and solvent removal significantly increased the contents of protein, ash and soluble carbohydrate, and decreased oil content, total phenolics and protein solubility. Pepsin digestibility ranged from 11 to 72%, and generally increased with processing. Sodium dodecyl sulphate–polyacrylamide gel electrophoresis of solubilized proteins showed the presence of four major polypeptide components, with only minimal changes in the protein profiles among the samples as a result of processing. The viscosity of the slurry was largely unaffected but shear thinning indices increased with processing. Multiple-regression analysis showed that protein content was related to carbohydrate content, cyanogenic content, and viscosity, but not associated with protein solubility and digestibility.

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