Development and characterization of maize starch nanoparticles using acid hydrolysis

Raw starch was modified to improve its functional qualities. Modification was carried out by preparing starch nanoparticles using acid hydrolysis. Hydrolysis was done on a magnetic stirrer for 7 days at 40°C followed by ultrasonication for 5 min. Starch nanoparticles were then characterized on the basis of their morphology, particle size, crystallanity, pasting and functional properties. The starch nanoparticles obtained by acid hydrolysis were found in round and oval shapes as shown by Transmission electron microscope (TEM). X-ray diffractometer revealed the crystalline behaviour of starch nanoparticles compared to raw starch. The crystallanity of starch nanoparticles decreased due to the processing conducted with acid. Functional properties viz. water absorption index (WAI), water solubility index (WSI) and swelling power got improved in starch nanoparticles as compared to the raw starch. Prolonged acid treatment of maize starch caused the disintegration of starch molecules which reduced the pasting viscosity to the extent that the pasting properties could not be estimated on Rapid Visco analyzer.