Effects of Three Emerging Non-thermal Pretreatments on Drying Kinetics, Physicochemical Quality, and Microstructure of Garlic Slices

Three emerging non-thermal pretreatment methods, including cold plasma, ultrasound, and ozone water, were utilized to pretreat garlic slices before drying process. The garlic slices were then dried by hot air drying at 60 degrees C. The study investigated the drying kinetics, color, rehydration ratio (RR), allicin content (AC), total phenolic content (TPC), antioxidant activity, and microstructure of the garlic slices. The results showed that ultrasound and ozone water pretreatment can significantly enhance drying kinetics. In comparison to untreated samples, garlic slices pretreated with ultrasound for 20 min exhibited a 55.96% increase in moisture effective diffusivity (Deff). Garlic pretreated with ultrasound exhibited the best rehydration properties, yet it retained the lowest levels of allicin content and antioxidant activity. Encouragingly, samples treated with ozone water demonstrated the best nutritional quality properties, with approximately 7.85% higher AC, 25.90% higher TPC, and 12.31% higher antioxidant activity compared to untreated samples. The study also emphasizes notable alterations in the microstructure of garlic resulting from various pretreatments. This research provides valuable insights into optimizing garlic drying processes using emerging non-thermal pretreatment techniques, showcasing their potential for industrial applications and quality enhancement.