Morphological characteristics, oxidative stability and enzymic hydrolysis of amylose-fatty acid complexes

•Morphology of complex was that of ordered lamellae separated from amorphous regions.•Amylose helices effectively protected the unsaturated fatty acids against oxidation.•Amylose-fatty acid complexes were fully bioavailable.

Complexes of amylose with fatty acids varying in carbon chain length and degree of unsaturation were prepared at 30, 50 or 70 °C by dissolving amylose in 0.1 N KOH and mixing with fatty acid potassium soap solution. The complexes were obtained in solid form as precipitates after neutralization. SEM microscopy revealed that the morphology of the complexes was that of ordered lamellae separated from amorphous regions whereas confocal laser scanning microscopy showed images of the topography of the guest molecules in the complex matrix. FTIR spectroscopy revealed that the absorption peak attributed to carbonyl group of free fatty acid was shifted when the fatty acid was in the form of amylose complex. Thermo-gravimetry showed that the unsaturated fatty acids were effectively protected from oxidation when they were complexed with amylose whereas enzymic hydrolysis experiments showed that the guest molecules were quantitatively released from the amylose complexes.