Process-induced compositional changes of flaxseed.
Flaxseed has been used as an edible grain in different parts of the world since ancient times. However, use of flaxseed oil has been limited due to its high content of polyunsaturated fatty acids. Nonetheless, alpha-linolenic acid, dietary fiber and lignans of flaxseed have regained attention. New varieties of flaxseed containing low levels of alpha-linolenic acid are available for edible oil extraction. Use of whole flaxseed in foods provides a means to utilise all of its nutrients and require minimum processing steps. However, the presence of cyanogenic glucosides and diglucosides in the seeds is a concern as they may release cyanide upon hydrolysis. In addition, the polyunsaturated fatty acids may undergo thermal or autooxidation when exposed to air or high temperatures that are used in food preparation. Studies todate on oxidation products of intact flaxseed lipids have not shown any harmful effects when flaxseed is included, up to 28%, in the baked products. Furthermore, cyanide levels produced as a result of autolysis are below the harmful limits to humans. However, the meals left after oil extraction require detoxification but, by solvent extraction, to reduce the harmful effects of cyanide when used in animal rations. Flaxseed meal is a good source of proteins; these could be isolated by complexation with sodium hexametaphosphate without changing their nutritional value or composition. In addition, the effect of germination on proteins, lipids, cyanogenic glycosides, and other minor constituents of flaxseed is discussed.
Wanasundara
P K
PK
Department of Biochemistry, Memorial University of Newfoundland, St. John's, Canada.
Shahidi
F
F
D000596:Amino Acids / Q000302:isolation & purification; D002241:Carbohydrates / Q000302:isolation & purification; D003486:Cyanides / Q000302:isolation & purification; D004042:Dietary Fats, Unsaturated / Q000302:isolation & purification; D019597:Flax / Q000737:chemistry*; D005504:Food Analysis; D005511:Food Handling; D018525:Germination; D006027:Glycosides / Q000302:isolation & purification; D006358:Hot Temperature; D008903:Minerals / Q000302:isolation & purification; D010084:Oxidation-Reduction; D010636:Phenols / Q000302:isolation & purification; D010833:Phytic Acid / Q000302:isolation & purification; D010940:Plant Proteins / Q000302:isolation & purification; D012639:Seeds / Q000737:chemistry*; D012997:Solvents; D014815:Vitamins / Q000302:isolation & purification
D000596:Amino Acids; D002241:Carbohydrates; D003486:Cyanides; D004042:Dietary Fats, Unsaturated; D006027:Glycosides; D008903:Minerals; D010636:Phenols; D010940:Plant Proteins; D012997:Solvents; D014815:Vitamins; D010833:Phytic Acid