Comparative effects of curcumin when delivered in a nanoemulsion or nanoparticle form for food applications: Study on stability and lipid oxidation inhibition

Recently, many published studies focus on optimizing synthesis of curcumin-nanocarriers by improving physicochemical properties and functionality. The comparative ability of nanocarriers to prevent deterioration of curcumin under processing and storage, particularly within food matrix, is addressed. Nanoemulsions and nanoparticles with entrapped curcumin were synthesized at the same level of surfactant concentration. The stability and functionality of emulsified or nanoentrapped-curcumin were determined relative to curcumin in nanosuspended form. All systems were subjected to conditions relevant to commercial applications. Protection of curcumin against degradation in varying pH and thermal treatments was better in zein nanoparticles, but these particles precipitated in the presence of salt. Nanoemulsions were more stable, but their surface charge decreased dramatically under thermal processing. The effect of nanoparticles on curcumin stability was less pronounced after 15 days storage compared with the nanoemulsions. The release of entrapped curcumin under phosphate buffer saline was sustained for 72 h for both nanosystems. When added to milk, both nanostructures had the potential to inhibit lipid oxidation, as indicated by an insignificant color change of the fortified milk after 5 days. This study provides insights which can help choose the most suitable nanocarrier for delivering curcumin as a food additive in different commercial products.