The physical stability and digestibility of β-carotene in oil-in-water sodium caseinate nanoemulsion

Consumption of carotenoids may reduce the risk of certain chronic diseases, but their use in foods is currently limited because of their low bioavailability and physicochemical instability. The purpose of this research was to evaluate the physical stability of beta-carotene (beta-CE) in oil-in-water sodium caseinate nanoemulsion under the conditions of pH, temperature, ion strength and storage time. beta-CE nanoemulsion is liable to aggregation at pH values close to the isoelectric point of the casein (pH 4-5). The beta-CE nanoemulsion shows preferable physical stability under the conditions of heat at 80 A degrees C for 90 min and ion strength (100-500 mmol/L). The physical stability of nanoemulsion in digestion model was also evaluated.Confocal images as well as droplet characterization in terms of size and charge indicate that the negative charge and Z-average of droplet size in different digestion stages are variant. beta-CE nanoemulsion became highly aggregated when exposed to gastric condition. The extent of the FFA release is increased with the increase of lipolysis time. These results have significant implications for using proteins to fabricate emulsion-based delivery system for beta-CE.