Preparation, characterization and functional properties of flax seed protein isolate
- Authors: Kaushik, Pratibha , Dowling, Kim , McKnight, Stafford , Barrow, Colin , Wang, Bo , Adhikari, Benu
- Date: 2016
- Type: Text , Journal article
- Relation: Food Chemistry Vol. 197, no. (2016/04/15/ 2016), p. 212-220
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- Description:
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 (375.51m2/g), highest emulsion stability index (179.5h) and zeta potential (−67.4mV) 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
Complex coacervation between flaxseed protein isolate and flaxseed gum
- Authors: Kaushik, Pratibha , Dowling, Kim , Barrow, Colin , Adhikari, Benu
- Date: 2015
- Type: Text , Journal article
- Relation: Food Research International Vol. 72, no. (2015), p. 91-97
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- Description:
Flaxseed protein isolate (FPI) and flaxseed gum (FG) were extracted, and the electrostatic complexation between these two biopolymers was studied as a function of pH and FPI-to-FG ratio using turbidimetric and electrophoretic mobility (zeta potential) tests. The zeta potential values of FPI, FG, and their mixtures at the FPI-to-FG ratios of 1:1, 3:1, 5:1, 10:1, 15:1 were measured over a pH range 8.0-1.5. The alteration of the secondary structure of FPI as a function of pH was studied using circular dichroism. The proportion of a-helical structure decreased, whereas both β-sheet structure and random coil structure increased with the lowering of pH from 8.0 to 3.0. The acidic pH affected the secondary structure of FPI and the unfolding of helix conformation facilitated the complexation of FPI with FG. The optimum FPI-to-FG ratio for complex coacervation was found to be 3:1. The critical pH values associated with the formation of soluble (pHc) and insoluble (pH
Φ1 ) complexes at the optimum FPI-to-FG ratio were found to be 6.0 and 4.5, respectively. The optimum pH (pHopt ) for the optimum complex coacervation was 3.1. The instability and dissolution of FPI-FG complex coacervates started (pHΦ2 ) at pH2.1. These findings contribute to the development of FPI-FG complex coacervates as delivery vehicles for unstable albeit valuable nutrients such as omega-3 fatty acids. © 2015.
Microencapsulation of flaxseed oil in flaxseed protein and flaxseed gum complex coacervates
- Authors: Kaushik, Pratibha , Dowling, Kim , McKnight, Stafford , Barrow, Colin , Adhikari, Benu
- Date: 2016
- Type: Text , Journal article
- Relation: Food Research International Vol. 86, no. (2016), p. 1-8
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- Description: Flaxseed oil, a rich source of omega-3 fatty acids, was microencapsulated in a novel matrix formed by complex coacervation between flaxseed protein isolate (FPI) and flaxseed gum (FG). This matrix was crosslinking with glutaraldehyde. Liquid microcapsules with three core (oil)-to-wall ratios (1:2, 1:3 and 1:4) were prepared and spray-dried or freeze-dried to produce powders. The microencapsulation efficiency, surface oil, morphology and oxidative stability of these microcapsules were determined. The spray-dried solid microcapsules had higher oil microencapsulation efficiency, lower surface oil content, smoother surface morphology and higher oxidation stability than the freeze-dried microcapsules. The highest microencapsulation efficiency obtained in spray-dried microcapsules was 87% with a surface oil of 2.78% at core-to-wall ratio 1:4 and oil load 20%. The oxidation stability obtained from spray-dried microcapsules at core-to-wall ratio of 1:4 was nearly double that of the unencapsulated flaxseed oil. © 2016 Elsevier Ltd.