Emerging technologies in watermelon juice Processing: Innovations in preservation and quality enhancement

Watermelon juice is recognized as a functional beverage due to its high concentrations of lycopene, β-carotene, vitamin C, amino acids, and polyphenols. However, its high perishability, driven by microbial spoilage, enzymatic browning, and oxidative degradation, and due to its high-water activity and low acidity presents significant challenges for commercial storage and distribution. Traditional preservation approaches such as thermal pasteurization ensure microbial safety but severely compromise sensory quality and nutritional integrity, leading to substantial losses of bioactive compounds and volatile flavor compounds. Consequently, the demand for innovative, minimally invasive processing technologies has intensified. In recent years, emerging technologies have been effectively evaluated in many research laboratories for the processing of watermelon juice. They are ultra-high temperature (UHT), continuous flow high-pressure homogenization (CFHPH), ultrasound and microwave-assisted processing, thermosonication, ozone, ultra-high pressure (UHP) treatments, and membrane filtration techniques applied for watermelon juice preservation. This review comprehensively explores the effect of these techniques on nutrient & bioactive retention, microbial and enzyme inactivation. The CFHPH at 300 MPa preserves higher levels of ascorbic acid, lycopene, and free amino acids while effectively inactivating polyphenol oxidase (PPO) and peroxidase (POD) activities. Ultrasound and microwave-assisted processes enhance antioxidant activity and shelf life by optimizing cell disruption and mass transfer effects. Ozone achieves microbial reductions comparable to pasteurization without inducing significant nutrient degradation. Comparative evaluation indicates that emerging technologies outperform conventional thermal methods in preserving nutritional attributes, sensory characteristics, antioxidant stability, and extending shelf life.