Effects of Ultrasound on Spoilage Microorganisms, Quality, and Antioxidant Capacity of Postharvest Cherry Tomatoes.

Mature-green cherry tomato fruits (Lycopersicon esculentum cv. Jinyu) were exposed to different power densities of ultrasound (66.64, 106.19, and 145.74 W/L) at 25 °C to study ultrasound non-thermal effects on the storage properties. Among the three levels of ultrasound irradiation, 106.19 W/L ultrasound was effective in reducing the spoilage microorganisms, delaying postharvest ripening through inhibiting ethylene production and respiration rates, and consequently maintaining fruit firmness, flavor, enzyme activities, antioxidants (total phenolics, total flavonoids), and the total antioxidant capacity of cherry tomatoes. The 66.64 W/L ultrasound had similar effects but to a lesser extent. Meanwhile, although 145.74 W/L ultrasound resulted in higher content of ascorbic acid (AA), it showed many negative effects on the storage quality of fruits. These results demonstrated that ultrasound of appropriate power density had great potentials in inhibiting decay, maintaining flavor and nutritional quality of cherry tomatoes. Recently, ultrasound has been considered as a multifunctional pretreatment method for the preservation of postharvest fruits and vegetables. Although the preservation effects were slight because of the screening of the thermal effects, its non-thermal effects presented potentials in improving storage quality of cherry tomato. Further studies are needed to explore the combinations between ultrasound with heating as well as other postharvest preservation technologies to enhance the effects of ultrasound. These explorations would facilitate the large-scale application of ultrasound in the preservation of fresh fruits and vegetables.