Effects of enzymatic modifications and botanical source on starch–stearic acid complex formation

Linear starch forms inclusion complexes with hydrophobic compounds, and the complexation is affected by many factors, such as the degree of polymerization (DP) of linear starch. Enzymatic modification of starch may create more linear starch with favorable DPs that could enhance starch‐inclusion complexation. Starches from different botanical sources, including potato, common corn, and high amylose corn starch (Hylon VII, ∼70% amylose), were modified enzymatically using isoamylase alone or combined with β‐amylase prior to complexing with stearic acid, and the resultant modified starches and their complexes were characterized. Debranching significantly increased iodine affinity (IA) of potato and common corn starch, but had no effect on Hylon VII; the additional β‐amylase treatment further increased IA of potato and common corn starches, but decreased IA of Hylon VII. The highest amount of complexed stearic acid as measured by gas chromatography was formed by the debranched and β‐amylase‐treated potato starch. All the starch complexes displayed a mixture of the B‐ and V‐type X‐ray diffraction patterns, with the debranched and β‐amylase‐treated starch complexes exhibiting more of the V‐type pattern. These results indicate that an additional β‐amylase treatment significantly increased complexation between starch and stearic acid for debranched potato and common corn starches, but debranching alone was sufficient to increase Hylon VII and stearic acid complexation under the present experimental conditions.