## 3 Results and Discussion  
### Effect of TP and TS on Salmonella Populations and Wax Gourd Firmness  
_Salmonella_ populations in fresh-cut wax gourd pieces treated with TP and TS were monitored using plate count, and the results are shown in Figure 1. It is evident that both TP and TS treatment can effectively reduce the population of _Salmonella_ in fresh-cut wax gourd. In general, TP treatments (TS treatment time = 0) reduced the _Salmonella_ population by about 0.3-0.7 log CFU/g, and higher concentrations of TP resulted in greater reductions in most cases. However, as TP concentration increased from 1% to 1.5%, the bacteriostatic effect did not improve proportionately. TS treatments (TP concentration = 0) could reduce _Salmonella_ population by about 1.5-4.7 log CFU/g, depending on the temperature and time used. Higher temperature and longer time had a greater effect on the reduction of _Salmonella_ population. The combination of TP and TS treatments showed better inactivation efficacy than each treatment independently. In this study, the best effect was observed with the combination of TP (1.5%) and TS (3 min at 60 \({}^{\circ}\)C), which reduced _Salmonella_ population by about 5.5 log CFU/g. Figure 1: Effect of thermosonication treatment with different treatment temperature (30, 40, 50, and 60 \({}^{\circ}\)C), treatment time (0, 1, 2, and 3 min), and tea polyphenols concentration (0, 0.5, 1.0, and 1.5%) on _Salmonella_ population (log CFU/g). Colors of bars represent treatment time, (Black) 0 min, (Dark grey) 1 min, (Light grey) 2 min, and (White) 3 min. Panels represent _Salmonella_ population treated with (**A**) 30 \({}^{\circ}\)C, (**B**) 40 \({}^{\circ}\)C, (**C**) 50 \({}^{\circ}\)C, and (**D**) 60 \({}^{\circ}\)C. In each panel, different letters on bars of various colors indicate significant differences at \(p\) < 0.05 using Student’s \(t\) test. The firmness of the wax gourd samples was evaluated using a digital texture analyzer, and the results were shown in (Supplementary Materials Figure S1). The results indicated that the firmness of wax gourd was primarily affected by the storage temperature and had little correlation with the TP and TS treatments. The higher the storage temperature, the faster the hardness decreased, particularly when stored at 25 \({}^{\circ}\)C, where the firmness of the wax gourd rapidly decreased. After six days of storage, the wax gourd became unmeasurable due to severe spoiling and softening. Further research is needed to fully understand the impact of TP and TS on the quality and sensory properties of wax gourd. TS has been widely used for pasteurization and _Salmonella_ inactivation in various food products. An earlier study evaluating the effect of TS on the survival of _Salmonella_ enterica in intact eggs found that the killing effect of TS was temperature dependent, with higher temperatures having a higher killing effect [37]. Another study found that TS at 60 \({}^{\circ}\)C had a higher inactivation effect than at 50 \({}^{\circ}\)C, and 5 min TS treatment at 60 \({}^{\circ}\)C could kill all _Salmonella Enteritidis_ cells in mango juice [38]. It was reported that 5 min TS at 60 \({}^{\circ}\)C could reduce _Salmonella enterica_ serovar Typhimurium on fresh-cut bell peppers by 2-3 log CFU/g [34]. Consistent with previous findings, our results suggested that TS Treatment at 60 \({}^{\circ}\)C had a higher inactivation efficacy against _Salmonella enterica_. Furthermore, a 3 min TS treatment at 60 \({}^{\circ}\)C could reduce _Salmonella enterica_ in fresh-cut wax gourd by about 4.5 log CFU/g, which is better than that in bell pepper but less effective than in mango juice. These differences in the effectiveness of TS treatment may be due to variations in food material matrix, such as state (solid or liquid), pH, organic acids, osmotic pressure, etc. TP has been used for the preservation of fresh-cut fruit and vegetables, as well as meat and fish products.