Application of Nanoliposome-Encapsulated Olive Seed Protein Hydrolysate to Improve the Physicochemical and Antioxidant Properties of Orange Juice during Storage

Abstract The incorporation of bioactive compounds into fruit juices is often limited by their instability and interactions with the food matrix. Encapsulation systems have emerged as an effective strategy to enhance the stability and functionality of these compounds. This study investigated the effects of free and nanoliposome-encapsulated olive seed protein hydrolysate (OSPH) on the physicochemical properties of orange juice during 30 days of storage. Orange juice was fortified with OSPH at two concentrations (2% and 4%, v/v) in free and encapsulated forms. Antioxidant activity, ferric reducing antioxidant power (FRAP), browning index, clarity, turbidity, cloudiness, phase separation, titratable acidity, color difference (ΔE), and viscosity were evaluated during storage. Antioxidant activity and FRAP decreased gradually, while browning index, turbidity, cloudiness, titratable acidity, phase separation, and ΔE increased over time. Samples containing OSPH, especially in encapsulated form, showed higher retention of antioxidant activity and FRAP, with lower changes in pH, acidity, color, and phase separation compared with control and free OSPH treatments. Although free OSPH increased browning, turbidity, and cloudiness, nanoliposome encapsulation reduced these negative effects and improved visual stability. All samples exhibited non-Newtonian shear-thinning behavior, while encapsulated treatments, particularly at 4% OSPH, demonstrated higher viscosity and improved rheological stability. Overall, nanoliposome encapsulation of OSPH effectively enhanced the physicochemical stability, antioxidant preservation, and quality of orange juice, highlighting its potential for developing functional beverages with improved nutritional value.