In this study, carotenoid-loaded nanoemulsions were prepared after extracting carotenoids from Gracilaria dura, Sargassum acinarium and Ulva rigida macroalgae collected from Türkiye seas by ultrasound-assisted enzymatic extraction for the first time. The extract added in oil phase and nanoemulsion prepared by high pressure homogenizator.
First, encapsulation efficiency, average particle size, zeta potential, visual appearance, color and creaming characteristics of emulsions were determined to optimize emulsion conditions. Then, thermal stability, pH stability, ionic strength stability, and color measurement were investigated for determination of physical stability of the nanoemulsified carotenoids (NCs). To determine storage stability, NCs were stored at 4 °C for 28-storage days and creaming index and oxidative stability assays of NCs were performed. According to the results of the study, the mean particle diameter of NCs ranged from 0.176±0.01 to 0.189±0.01 nm and the particle charges varied between -17.6±1.18 and -24.35±0.92 mV. NC remained stable against coalescence over a wide pH values ranged from 3 to 7. Among NCs, the concentration of NaCl at which the net charge decreased the most was the emulsion containing 200 mM NaCl. All NCs were stable between 30-80 °C. Color discoloration of NCs occurred during the storage period of 28-days. NCs of S. acinarium with the smallest particle size showed minimal creaming and an anticipated lower creaming index because smaller oil droplet size was linked to a lower creaming index. On the other hand, NCs of U. rigida continuously had the lowest zeta potential of all the nanoemulsions during the storage period, suggesting an early creaming trend. On the 5th day of storage, the lipid hydroperoxides production of NCs increased significantly, and this increase continued throughout the storage period (p<0.05).