Preparation and characterization of corn starch-β-carotene composites

Starch-β-carotene composites were generated by drop-wise addition of ethanol comprising varying β-carotene contents (5, 10, or 20 mg) into starch pastes (1, 3, or 5% w/v) to improve water-dispersibility and stability of β-carotene. The mean diameter of the composites was less than 900 nm, allowing particles to be homogeneously dispersed in aqueous media for over two weeks without sedimentation. X-ray diffraction and differential scanning calorimetry analysis confirmed the composite mainly consisted of Vh-amylose, amorphous starch matrices, and starch-β-carotene ordered structures. Both amorphous matrices and Vh-amylose structures in the composite were readily digested within 20 min in vitro digestion, while highly ordered structures, which melted between 132 and 159 °C, exhibited inhibited and/or delayed enzymatic digestion. As more β-carotene was incorporated into the composite, the β-carotene content of the ordered structure was increased. Formation of starch-β-carotene composites also appeared to enhance the stability of β-carotene against chemical oxidation.