Dual-functional ultrasound-activated sonosensitizer for microbial inactivation and sprouts quality enhancement

The increasing demand for safe, ready-to-eat sprouts highlights the need for effective and environmentally friendly disinfection methods. Curcumin is a natural compound with potent sonosensitizing properties, capable of generating reactive oxygen species (ROS) under ultrasound (US) irradiation to inactivate microorganisms. In this study, the combined effects of ultrasound and a curcumin-based emulsion labelled as curcumin-lecithin-propyl gallate-zein (CLPGZ) on the inactivation of Salmonella enterica serovar Typhimurium, and the growth performance of mung bean and pea sprouts were investigated. The results showed that a curcumin concentration of 0.17 mg/mL combined with 15 min of ultrasound treatment (345 W/cm²) achieved more than 99.5% bacterial reduction meanwhile maintaining a germination rate above 85% and producing the longest shoot length compared to other treatments. Physicochemical characterization confirmed that the CLPGZ emulsion remained stable over 60 days, with a consistently low polydispersity index of approximately 0.2. Beyond microbial inactivation, the combined treatment also significantly improved the nutritional and antioxidant profiles of sprouts, as reflected by increased reducing sugars, proteins, and antioxidant enzyme activities. In particular, relative to the control group, the combined treatment increased total phenolic content by 22.5% in mung bean sprouts and 45.8% in pea sprouts, with corresponding increases of 12.2% and 9.7% in DPPH radical scavenging activity (P < 0.05). In addition to reducing seed surface contamination, the treatment decreased wash water microbial loads to below the detection limit (< 2.0 log CFU/mL), underscoring its potential to reduce the risk of cross-contamination during postharvest handling. The integration of this food-grade sonosensitizing emulsion with ultrasound represents a practical approach for improving microbial safety and quality attributes in sprout processing.