Key Findings
Flaxseed protein is composed of two protein fractions: a salt soluble, high molecular weight (11S–12S) fraction; and a water soluble, low molecular weight (1.6S–2S) fraction. Flaxseed protein is rich in aspartic acid, glutamic acid, leucine and arginine. Its protein possesses functional properties, such as high emulsifying activity and foaming capacity. The study describes technologies to (1) optimise the extraction of a 90% flaxseed protein isolate (FPI) and maximise its yield, without compromising protein purity by minimizing the interference of flaxseed mucilage in protein extraction and (2) characterise the physiochemical properties (thermal stability, solubility, and electrostatic charge density) of the extracted FPI. The functional properties (emulsion activity index, emulsion stability index, water holding and fat absorption capacity emulsion droplet size and charge density) of FPI were found to be comparable to commonly used proteins, such as Gel, WPI, SC and SPI.
Abstract
Flaxseed protein isolate (FPI) was extracted from flaxseeds, and its amino acid composition and functional properties (solubility, thermal stability, emulsifying properties and electrostatic charge density, water holding and fat absorption capacities) were determined. The highest purity of FPI (90.6%) was achieved by extraction at 60°C. FPI had a low lysine to arginine ratio of 0.25, which is desired in heart-healthy foods and infant formulas. The denaturation temperature of FPI was 105°C. FPI had the highest emulsion activity index (375.51 m(2)/g), highest emulsion stability index (179.5 h) and zeta potential (-67.4 mV) when compared to those of other commonly used proteins, such as sodium caseinate (SC), whey protein isolate (WPI), gelatin (Gel) and soy protein isolate (SPI). The average emulsion droplet size of emulsions stabilized by these proteins was in the order SC<FPI<WPI<Gel<SPI. Water holding and fat absorption capacities of FPI were similar to those of the above mentioned proteins.
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