Effect of Thermal and Non-thermal Treatments on Bell Pepper–pineapple Juice During Cold Storage

This study evaluated the effects of five preservation methods control, UV-C (254 nm, 40 min), mild thermal pasteurization (65 °C, 15 min), ultrasound (65 °C, 15 min), and chitosan addition (0.2 g·200 mL-1) on a 1:1 (v·v-1) bell pepper-pineapple juice blend stored at 4 ± 2 °C for 13 days. The untreated juice was rich in vitamin C, polyphenols, and flavonoids but prone to spoilage and oxidation. All treatments led to gradual declines in quality, though the chitosan group best preserved pH, total phenolic content (TPC), flavonoids (TFC), and DPPH antioxidant activity, and showed the lowest microbial growth. Ultrasound and UV-C provided moderate protection, whereas thermal treatment caused the most significant degradation of nutrients. The results highlight chitosan as the most effective strategy, supporting the use of non-thermal and bioactive-integrated technologies for extending the shelf life of antioxidant-rich juice blends in a sustainable manner. Keywords: Antioxidants, Bell pepper, Chitosan, Cold storage, Non-thermal preservation, Pineapple juice.