## 2 Results and Discussion
### Effects of HPP and TS Processing on Quality Properties during Different Storage Conditions
#### 2.2.2 Color Changes  
Tables S1 and 3 show the changes in L*, a*, b*, and \(\Delta\)E values in the HPP and TS marinated lotus root slices during storage at 45 \({}^{\circ}\)C, 25 \({}^{\circ}\)C, and 4 \({}^{\circ}\)C. The quality of the lotus root is mainly reflected by the changes in color, specifically in lightness and yellowness [42]. The L* values of both HPP and TS marinated lotus root slices decreased continuously with storage time, indicating that the color darkened during storage. There was a significant decrease in b* values for marinated lotus root slices during storage, indicating that the yellow hue in marinated lotus root slices degraded significantly. This result was similar to that of a previous study on HPP carrots and thermally processed strawberry pure [30; 43]. The \(\Delta\)E values of marinated lotus root slices significantly increased during storage, indicating that the color quality declined as the storage period increased. The color changes observed in marinated lotus roots during storage may be due to a variety of causes, such as enzymatic or non-enzymatic browning reactions and microbial spoilage [44; 45]. However, the \(\Delta\)E values of the HPP samples were consistently lower than those of the TS samples of the same period at the same storage temperature. Similar results were also found for marinated radish and cloudy kiwifruit juice [1; 46]. Therefore, HPP can maintain the original color of the marinated lotus root slices better than the TS process.  
In addition, the color of marinated lotus root slices was also affected by storage temperature. HPP and TS samples stored at 4 \({}^{\circ}\)C showed more stable color quality than samples stored at 25 \({}^{\circ}\)C, with the worst quality being observed in samples stored at 45 \({}^{\circ}\)C. The rate of increase in the \(\Delta\)E values increased with increasing storage temperature, indicating that the rate of browning reactions was accelerated at high storage temperatures. [PERSON] et al. [42] reported similar results for freshly cut lotus root. This is because low temperatures reduce enzymatic browning reactions by decreasing enzyme activity and also reduce non-enzymatic browning reactions such as the Maillard reactions and ascorbic acid degradation [35; 42; 47]. Based on previously published reports, it is unclear whether the effect of storage temperature on the color of HPP samples differs from that of thermally processed samples. Studies performed on orange juice [48] and aloe vera-lithi mixed beverage [49] showed that the color change of HPP samples was more affected by storage temperature than that of thermally processed samples. Opposite results have been reported for clear and cloudy Se-enriched kiwifruit juice [45]. In our study, the color changes of HPP and TS marinated lotus root slices were similarly affected by storage temperature. Therefore, appropriate storage temperatures combined with optimal processing technology help to better preserve the appearance of marinated lotus root slices.  
Figure 2: Changes in hardness of HPP and TS marinated lotus root slices during storage: (**A**) storage at 45 \({}^{\circ}\)C, (**B**) storage at 25 \({}^{\circ}\)C, (**C**) storage at 4 \({}^{\circ}\)C. Different letters indicate significant differences during storage (\(p<0.05\)) for the HPP (uppercase letters) and TS (lowercase letters) marinated lotus root slices. * \(p<0.05\). HPP, high-pressure processing; TS, thermal-and-soaking.