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FLAXSEED (Linum usitatissimum L.) GUM AND ITS DERIVATIVES: PHYSICOCHEMICAL PROPERTIES AND POTENTIAL INTERACTIONS WITH FOOD MACROMOLECULES

Date

2016-04-19

Authors

Journal Title

Journal ISSN

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Publisher

ORCID

Type

Degree Level

Doctoral

Abstract

Flaxseed (Linum usitatissimum L.) gum (FG) is a material with many potential food and non-food applications. Consistent performance is critical for FG utilization and this is possible through selection of genotype, characterization and optimization of constituents, and chemical modification. Physico-chemical and functional properties of FG aqueous solutions from six Canadian flaxseed cultivars were investigated. FG yield, carbohydrate composition, protein content, and zeta potential (ζ) varied among these cultivars. FG solution properties were also affected by temperature, solution pH, NaCl concentration, and sucrose concentration. Detailed studies were conducted on CDC Bethune FG (FGB) proteins that were separated by 2D-gel electrophoresis. Conlinin was identified as the major protein. Protease treatment decreased FGB solution emulsification properties suggesting that conlinin might enhance emulsification. Formation of BSA-FGB coacervates was monitored by turbidimetric analysis as a function of solution pH, biopolymer mixing ratio, NaCl and urea. Coacervates were stabilized primarily by attractive electrostatic forces and secondarily by hydrogen bonds. Further, anionic carboxymethyl ether moieties were introduced to FGB structure through ether forming reactions using monochloroacetic acid (MCA) to produce products with uniform properties. The highest degree of substitution (DS) was obtained at 70 °C, 7.0 M NaOH, and a molar ratio of MCA to FGB of 10:1 over 3 h. Carboxymethylated FGB (CMFG) exhibited both modified surface morphology and thermal behaviour. Solutions of CMFG demonstrated shear-thinning behaviour and apparent viscosity decreased with increased DS. A more liquid-like flow behaviour was observed for CMFG as DS increased. Findings here will introduce and expand FG applications in food or related fields with targeted performance.

Description

Keywords

Flaxseed gum, Flaxseed cultivars, Compositional analysis, Physico-chemical properties, Rheological properties, Conlinin, Emulsification properties, Complex coacervation, Carboxymethylation

Citation

Degree

Doctor of Philosophy (Ph.D.)

Department

Food and Bioproduct Sciences

Program

Food Science

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DOI

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