Synthesis and characterization of amylose–zinc inclusion complexes

• The amylose–zinc inclusion complex was synthesized.
• The effect of parameters on the zinc content and conversion rate was studied.
• Zinc was mainly coordinated to the oxygen atoms of the glucose unit 6-CH2OH.

Amylose–zinc inclusion complexes were synthesized using zinc chloride and amylose, which is obtained by completely debranching potato starch using pullulanase. Based on the zinc content (W–Zn) and zinc conversion (C–Zn), the reaction parameters, such as reaction time, reaction temperature, pH value and amount of zinc chloride added, were evaluated. The W–Zn and C–Zn of the zinc-loaded amylose, which was prepared under optimal conditions, were 128 mg/g and 82.05%, respectively. The Raman spectra showed that amylose formed a special single helix structure after complexing with zinc. X-Ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC) results showed that starch and zinc could formate the inclusion complexes. Moreover, the formation of amylose–zinc inclusion complexes was confirmed by the results of X-ray photoelectron spectroscopy (XPS) and 13C CP/MAS NMR, which suggests that zinc was mainly coordinated to the oxygen atoms of the glucose unit, 6-CH2OH. Thermal properties of the complexes were influenced by the zincatation process. This approach not only enlarged the number of fields for amylose use but also exhibited the extensive potential applications for zinc nutrition fortifier research. The study suggested that potato amylose might be a good carrier of zinc for nutritional supplementation purposes.