Flaxseed gums and their absorption on whey protein-stabilized oil-in-water emulsions
Flaxseed gums and their absorption on whey protein-stabilized oil-in-water emulsions
Year: 2009
Authors: Khalloufi, S. Corredig, M. Goff, D.H. Alexander, M.
Publication Name: Food Hydrocolloids
Publication Details: Volume 23; Pages 611-618.
Abstract:
The effect of the addition of flaxseed gum on the physicochemical properties of whey protein-stabilized (WPI) oil-in-water emulsions at pH 3.5 was investigated. Two different varieties (Emerson and McDuff) were tested at concentrations ranging from 0% to 0.33% (w/v), by measuring droplet size, z-potential, phase separation behavior, microstructure and apparent viscosity. With addition of flaxseed gum the zpotential of the droplets decreased from around 30 mV to a negative value (-10 mV) at concentrations >0.2%. These results indicated that the negatively charged polysaccharide fraction from flaxseed interacted with the protein adsorbed at the interface. An increase in apparent particle size was also noted with increasing flaxseed concentration, with destabilization becoming visually evident at concentrations higher than 0.1% (w/v). Microscopy, rheological data and size distribution analysis demonstrated for the first time that flaxseed gum interacts with protein-stabilized oil droplets at low pH, causing bridging flocculation. No significant differences were noted between flaxseed gums extracted from the Emerson and McDuff varieties. This research demonstrated that the electrostatic interactions between flaxseed gums and protein-stabilized emulsions need to be controlled when designing novel acidic beverages containing these polysaccharides. (Author's abstract)
Flaxseed gums are commonly employed in the cosmetic industry as texturing agents; however, in the food industry, their application has not yet been extensively examined. Polysaccharides extracted from flaxseed have shown promise as a novel food ingredient, however, very little is understood on its effect when added to food emulsions. Flaxseed gum can be extracted with water either from the fiber portion or from the whole seed. The extraction yield, the level of protein, and the physicochemical properties of gum are a function of temperature, pH, ratio of water to seeds, duration of the extraction and variety of the raw material. A better understanding of the interactions between flax polysaccharide and other ingredients is required before considering the use of flaxseed gum in food systems. The objective of this study was to assess the behaviour of flaxseed gums when mixed with a whey protein-stabilized oil-in-water emulsion at acidic pH. The choice of the two varieties of flaxseed gums used in this work, Emerson and McDuff, was based on their differences in terms of acidic and neutral fractions. The paper describes the various characteristics of flaxseed gums and the varietal differences that were found. (Editor's comments)
