A Three Component Interaction among Starch, Protein, and Free Fatty Acids Revealed by Pasting Profiles

A three way interaction among starch, protein, and lipid that affects the Rapid Viscoanalyzer (RVA) paste viscosity profile was revealed using a model system composed of isolated sorghum starch, whey protein isolate, and free fatty acids (FFAs) (20:2:1, w/w/w). A prominent cooling stage viscosity peak in the RVA profile was produced when all three components were present in the system, while there was no viscosity peak when either protein or FFA alone was combined with starch. The magnitude of the cooling stage viscosity peak differed with addition of palmitic, oleic, or linoleic acids to starch and protein. Amylose was the major functional molecule of the starch component. Addition of both protein and FFA to starch substantially reduced starch solubility after gelatinization, while solubility was less affected by single addition of FFA and was not affected by protein. Nonspecificity of this interaction phenomenon was demonstrated by similar results using maize starch and other soluble proteins. Keywords: Starch; protein; free fatty acid; interaction; paste viscosity