Encapsulation strategies for controlled iron delivery and designing functional foods

To address iron-deficiency anaemia, recently colloidal systems and cyclodextrins have been of research interest. Cyclodextrins or the designed colloidal systems with these cyclic oligosaccharides enable inclusion complex formation with micronutrients or nutraceuticals, while providing the possibility of simultaneous delivery of several hydrophobic/hydrophilic bioactive ingredients, masking their undesired taste, increasing their solubility and bioavailability, and achieving their targeted and controlled release. The present work discusses colloidal multiple emulsions stabilized by synthetic and biopolymeric stabilizers such as poly/oligosaccharides and their complexes with proteins for controlled delivery/co-delivery of different iron compounds (i.e. ferric sodium EDTA and ferrous sulphate) and a nutraceutical (i.e. curcumin) with potential applications in food fortification. Modelling approaches based on experimental results facilitated the design of stable delivery systems with enhanced iron and curcumin bioaccessibility which provided insights into the kinetics of release, diffusion mechanism of the compounds, and chemistry of ingredients impacted by the selected oil, emulsifiers, phase ratios, and positioning of the encapsulated compounds. Inclusion complex formation between cyclodextrins and different iron sources could be optimized through the control of factors showing synergistic or antagonistic effects on the inclusion rate (IR%), such as the types and concentrations of cyclodextrin and co-solvent, and operating conditions including mixing duration. The optimized delivery systems of β-cyclodextrin and its inclusion complex with ferrous ammonium phosphate, resulted in a high IR% of iron (∼96%) with enhanced thermal stability, demonstrated by a significant increase in melting temperature (T_m) from ∼172 to ∼294 °C. The system is potentially applicable to iron delivery in foods processed at elevated temperatures.