Imaging inclusion complex formation in starch granules using confocal laser scanning microscopy

The tendency of amylose to form inclusion complexes with guest molecules has been an object of wide interest due to its fundamental role in food processing. Here we investigated the features of starch granules from several botanical sources using confocal laser scanning microscopy (CLSM) and uncovered the interactions between amylose and fluorescent lipophilic molecules below gelatinization temperature. In natural starch granules, we reveal complexation of lipophilic molecules labeled with fluorescein with amylose located at the periphery of the granules, appearing as a bright well-defined luminescent rim. This phenomenon is occurring below the gelatinization point for very low concentration of aliphatic chains. Control experiments performed with the fluorescein dye show staining of the whole granule, evidencing non-specific interactions. Similarly, experiments performed with waxy granules show a broader luminescent rim when interacting with the lipid-dye molecules.