ARS | Publication request: Influence of pH and temperature on the rheological properties of aqueous dispersions of starch-sodium palmitate complexes

Submitted to: Carbohydrate Polymers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 22, 2011
Publication Date: March 17, 2012
Citation: Byars, J.A., Fanta, G.F., Kenar, J.A., Felker, F.C. 2012. Influence of pH and temperature on the rheological properties of aqueous dispersions of starch-sodium palmitate complexes. Carbohydrate Polymers. 88:91-95.

Interpretive Summary: Steam jet cooking is used as a method to prepare materials that can replace more expensive gums or chemically modified starches. This work shows that if high amylose corn starch is jet cooked with sodium palmitate, gels can be formed. Changing the pH produces materials with a wide range of physical properties. These materials are inexpensive replacements for gums, and can be used in applications such as thickeners and dispersants for lipids in foods, lotions and water-based lubricants.

Technical Abstract: Aqueous dispersions of high-amylose corn starch were steam jet cooked and blended with aqueous solutions of sodium palmitate to form amylose inclusion complexes. The rheology of dispersions of these complexes was examined. Acetic acid was added to reduce the pH, converting complexed sodium palmitate to palmitic acid. Associations of the complexed palmitic acid and reduced electrostatic repulsion resulted in a sharp increase in the linear viscoelastic properties of the gels. Further reduction of the pH led to precipitation of palmitic acid complexes and a decrease in the gel strength. Temperature ramps showed a sharp, reversible decrease in the elastic modulus. The temperature at which this decrease occurred depended on both the concentration and pH.