Flaxseed gum a versatile natural hydrocolloid for food and non-food applications

Flaxseed (Linum usitatissimum L.) gum (FG) is a by-product of the flax oil industry which can be easily prepared from flaxseed meal, flaxseed hull and/or whole flaxseed. FG has many potential food and non-food applications as it imparts marked solution properties and is proposed to have nutritional values as dietary fiber. However, FG is underutilized due to constituents with non-consistent physicochemical and functional properties. The present review provides an update of recent research into FG composition including its major constituents, proteins and polysaccharides. The review also describes findings related to FG solution physico-chemical properties including rheological, gelation, and emulsification properties that potentially determine FG applications. Possible FG structural modifications (crosslinking, esterification, and etherification) and interactions with proteins are also reviewed to elucidate strategies for FG utilization through manipulation of controllable properties. Flaxseed cultivars exhibit substantial genotypic variation with respect to monosaccharide and polysaccharide composition, molecular weight, and protein contents. Thus, selection of flaxseed genotype can help to optimize FG composition and benefit FG product design where specific functional and nutritional properties are required. Structural modification of FG polysaccharides offers another way for targeted tuning of FG properties and to minimize the inherent drawbacks of FG polysaccharides. Moreover, FG-protein interactions can also be engineered. Based on the mechanistic understanding of FG-protein interaction, FG-protein complexes can be utilized as texture modifiers, emulsifiers, and matrixes for bioactive nutrients encapsulation etc. to impart desired properties to foods, cosmetics, pharmaceutics, and medicines.