Starch nanoparticles: Isolation, characterization and applications

• Author / Creator

  Perez Herrera, Mariana

• Starch nanoparticles (SNP) were isolated by acid hydrolysis from starches varying in amylose content and crystalline type, and physicochemically characterized in terms of their morphology, particle size, crystallinity, molecular size distribution, chain length distribution, amylase resistance and thermal and rheological properties. Scanning electron microscopy and dynamic light scattering studies revealed that the SNP varied in size (50-500 nm) and shape (elliptical, oval, irregular, polygonal) according to the starch type. X-ray diffraction confirmed a crystalline transformation from B-type to A-type in B-type SNP, while A-type SNP remained the same as the native starch. The data indicated a positive correlation between the amylose content and SNP yield. A model for the release of SNP as individual amylopectin blocklets and the formation of recrystallized short chain amylose spherulites during the acid hydrolysis treatment was postulated. The average molecular weight and linear chain length distribution of SNP were determined by high performance size exclusion chromatography and high performance anion exchange chromatography with pulsed amperometric detector, respectively. Different eluting profiles and detectable degrees of polymerization were observed between waxy, normal, hylon V and hylon VII starches. The resistance of maize SNP towards amylolysis followed the order: hylon VII > hylon V > normal > waxy. The data showed the potential amylose involvement in the SNP structure of B-type high amylose maize starches. A rheological study confirmed that the variations in the starch source, morphology and thermal stability of SNP influence their viscosity and viscoelastic properties as a function of shear rate, frequency and temperature. Regardless of the starch source, all SNP suspensions at 5% (w/v) exhibited a viscosity profile similar to that of lyotropic liquid crystal polymers like cellulose nanocrystals. The data suggested that processing conditions such as heating temperature and shearing can alter the functional properties of SNP. The potential application of SNP as a texture modifier in different gum systems (λ-carrageenan, xanthan) was also investigated. Binary blends consisting of 0.5% (w/v) gum and different concentrations of SNP (waxy and hylon VII) were prepared. The effect of SNP source and concentration on the viscosity and viscoelastic behaviour varied with gum type. The addition of SNP helped maintain a stable viscoelastic behaviour in particular in gum systems with low viscosity and elasticity such as λ-carrageenan, whereas it did not significantly change the rheological behaviour of a high viscosity system like xanthan gum.

• Subjects / Keywords

  • Starch nanoparticles
  • Rheology
  • Molecular properties
  • Acid hydrolysis
  • Characterisation

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3HD7P50T

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.