Unveiling the mechanism of ultrasound-assisted phenolic extraction from Psidium cattleianum leaves: Kinetic, mass transfer, and thermodynamic insights

Strawberry guava leaves (Psidium cattleianum) are an attractive phenolic-rich byproduct for food and pharmaceutical production, with potential benefits for human health due to their exceptional antioxidant activity among plant-based resources. However, there are no systematic studies on sonochemical phenolic extraction from this material. Therefore, the goal of this study was to unveil the mechanism of ultrasound-assisted extraction (UAE) for phenolic recovery from Psidium cattleianum leaves. Pseudo-second-order kinetic modeling, Biot number, and thermodynamic analysis were introduced to describe the extraction mechanisms and then kinetic parameters such as saturation concentration (C_s), extraction rate (k), diffusion coefficient (D_eff), and mass transfer coefficient (K_T) compared with conventional shaking extraction (CSE) to establish the process intensification benefits. The result of pseudo-second-order kinetic analysis revealed a biphasic extraction mechanism consisting of initial rapid release, followed by diffusion-controlled mass transfer, with internal mass transfer identified as the rate-limiting step (Bi > 50). The UAE process was spontaneous (ΔG^o < 0), endothermic (ΔH^o = 3.8151 kJ/mol), and entropy-driven (ΔS^o > 0). The presence of ultrasound technology enabled UAE to demonstrate superior performance compared to CSE, which significantly increased C_s, k, D_e and K_T. Taken together, the integration of kinetic and thermodynamic analyses offers a robust framework for understanding sonochemical processes and fundamental insights into the nature of UAE from Psidium cattleianum leaves, thereby overcoming scale-up challenges and facilitating industrial applications.