Complexation induced changes of rheological properties of starch systems at different moisture levels

• Published in: Journal of rheology (New York : 1978) Vol. 39; no. 6; pp. 1497 - 1518
• Main Authors: Conde‐Petit, Béatrice, Escher, Felix
• Format: Journal Article
• Language: English
• Published: 01.11.1995
• Subjects: Viscoelasticity; GELS; GRANULAR MATERIALS; Starch; COMPLEXES; TRIGLYCERIDES; VISCOSITY; EMULSIFIERS; Lipid‐amylose complexes, rheology of; MOISTURE; Extensional flows; Amylose complexes, rheology of; EXTRUSION
• ISSN: 0148-6055; 1520-8516
• DOI: 10.1122/1.550612

Starch, especially the linear amylose fraction, is able to form helical inclusion compounds or complexes with molecules like flavor compounds, fatty acids, and emulsifiers. The effects of starch complexation on rheological properties were studied (a) in aqueous dispersions of 1%–4% starch content, (b) in high‐concentration gels of 40% starch content, and (c) in extrusion cooked low moisture starch blends. Complexation was followed by iodine binding capacity of starch and by differential scanning calorimetry. Rheological characterization was based on dynamic and steady shear measurements and on uniaxial force deformation tests. At low starch concentrations, the addition of complexing emulsifiers and flavor compounds induced gelation, provided that enough amylose was solubilized and swollen granules were present. Likewise, freshly prepared high‐concentration starch gels with the addition of complexing ligands exhibited higher moduli of deformability than control samples without additives. The sequence of moduli of elasticity became inverse during storage as complexation lowered the rate of amylose retrogradation. Melt viscosity during cooking extrusion increased with the addition of both complexing emulsifiers and noncomplexing triglycerides, while paste viscosity of ground extrudates increased with emulsifiers but not with triglycerides. Influence of starch complexation seems to be parallel for all moisture levels indicating that the main feature is the formation of insoluble amylose complexes which in turn lead to the formation of a firmer network between the dispersed starch granules.