Parameter Analysis and Applications of Ultrasonic and Hydrodynamic Cavitation Techniques in Plant Protein Extraction

Cavitation-based processing techniques, such as ultrasonic cavitation (UC) and hydrodynamic cavitation (HDC), have gained significant attention for their low energy consumption and high efficiency in food processing. Cavitation involves the formation and collapse of bubbles, releasing energy that enhances processes like microbial inactivation, drying, freezing, and extraction of natural compounds. This study reviews the mechanisms of UC and HDC, the factors influencing their effectiveness, and their applications in extracting plant proteins. And the study also explores their impact on recovery rates, structural properties, functional characteristics, nutritional quality, and energy efficiency when extracting protein from plant materials. Before using these cavitation technologies for plant protein extraction, a response surface methodology was used to study the effects of ultrasonic parameters such as temperature, duration, and amplitude on cavitation efficiency. Results indicated that increasing ultrasonic amplitude and treatment duration improved cavitation efficiency, while higher temperatures reduced it. The optimal conditions were found at 29°C, 30 min, and 100% amplitude. Based on the results, 100% amplitude and room temperature were used in following experiments. Various cavitation techniques including ultrasonic bath (USB), ultrasonic plate (US-plate), ultrasonic probe (US-probe), and hydrodynamic cavitation (HDC) were tested for protein extraction from peas. The US-probe demonstrated the highest protein recovery rate among all lab-scale cavitation devices, while HDC showed significant potential for scaling up. Compared to conventional method, HDC improved the purity and recovery rate of pea protein isolates (PPI). Further structural analysis confirmed that cavitation preserved the primary structure of PPI while significantly altering their secondary and tertiary structures, especially under the US-probe treatment. The study also examined the impact of cavitation on the functional properties of plant proteins, using a combined ultrasonic and microwave extraction (UMSE) technology to extract lupin protein. UMSE treatments significantly outperformed conventional methods, exhibiting a synergistic effect, increasing the yield and recovery rate. Lower power combinations enhanced solubility and reduced particle size, while higher power combinations led to protein denaturation, affecting solubility and particle size. To explore the industrial potential of cavitation technology, the study scaled up protein extraction from oat hull using two HDC devices. The results showed a significant increase in protein extraction efficiency and energy efficiency using HDC compared to conventional methods. In addition, HDC-treated proteins exhibited higher digestibility, amino acid content, phenolic content, and antioxidant activity. Overall, the study highlights the advantages of cavitation-based technologies, such as UC, UMSE and HDC, for efficient and sustainable plant protein extraction. These methods offer improved recovery rates, structural and functional properties, and enhanced energy efficiency, making them potentially suitable for large-scale industrial applications.