## 4 Discussion  
In China, the yields of red jujube fruits and bamboo shoots are very high. Red jujube fruits are usually dried to extend their shelf life, but the extremely low moisture content greatly affects the taste of the dried red jujube fruits. Meanwhile, bamboo shoots are usually caused due to their short shelf life. These limitations greatly affect their off-season consumption and full utilization of nutritional values. In recent years, plant-based beverages, as an alternative to acid dairy products, have become more popular, and they provide an option for making full use of the nutrients of red jujube fruits and bamboo shoots in all seasons, suggesting the great potential of these two materials with a short shelf life for beverage development. Red jujube is an excellent raw material for improving the flavor and antioxidant activity of the beverage, and bamboo shoot is rich in dietary fibers, thus being beneficial to the human intestines. [PERSON] et al. [35] studied the effects of red jujube pulps on the quality characteristics and antioxidant activity of goat milk yogurt, and they found that adding red jujube pulps could significantly reduce the flavor, improve the sensory acceptance, and increase the antioxidant activity of yogurts. [PERSON] and [PERSON] [36] introduced the rich nutrients of bamboo shoot and considered it as a portion of health food. Eating foods high in dietary fibers can reduce harmful cholesterol in the blood, maintain digestive health, and improve constipation. The beverage prepared by combining the nutritional values of the two raw materials and the fermentation of _L. plantarum_ will have potential market value. Fermentation may be an effective method for inhibiting the growth of potentially pathogenic bacteria in foods, which can improve the safety of products. [PERSON], [PERSON], and [PERSON] [37] developed a quinoa fermented beverage using _L. plantarum_ DSM 9843 and quinoa, with a significant decrease in the pH value of the beverage and an obvious increase in the content of lactic acid after 48 h of fermentation. In the present study, it was shown that _L. plantarum_ TUST-232 can not only use the nutrients in the beverage for rapid growth, but also produce a large amount of lactic acid. Meanwhile, the final pH value of the beverage was also lower than 4, which is one of the crucial characteristics for the safety of a beverage [38]. When the pH value is lower than 4, the growth of pathogenic bacteria can be inhibited in the beverage, thereby extending shelf life and improving safety [39]. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **L*** & **a*** & **b*** & \(\Delta\text{L*}\) & \(\Delta\text{A*}\) & \(\Delta\text{B*}\) & \(\Delta\text{E*}_{\text{ab}}\) \\ \hline Before & 38.47 \(\pm\) 0.40 & 14.42 \(\pm\) 0.19 & 45.00 \(\pm\) 0.20 & - & - & - & - \\ After & 38.50 \(\pm\) 0.19 & 14.32 \(\pm\) 0.09 & 44.81 \(\pm\) 0.12 & 0.03 \(\pm\) 0.59 & \(-\)0.10 \(\pm\) 0.28 & \(-\)0.19 \(\pm\) 0.32 & 0.89 \\ \hline \hline \end{tabular}  
* \(\Delta\text{E}^{*}_{\text{ab}}\), the change in color; L* (lightness); +L*, brighter; \(-\text{L*}\), darker; a* (red/green component); +a*, redder; \(-\text{a*}\), greener; b* (yellow/blue component); +b*, yellower; \(-\text{b*}\), bluer. The error bars indicate means \(\pm\) SD (\(n=3\)); the differences between groups were analyzed by a two-tailed paired Student’s _t_-test.  
\end{table} 
Table 4: Changes in color before and after fermentation of the R–B mixed juice with _L. plantarum_ TUST-232. Although the lower pH value is beneficial to improve the shelf life of the beverage, it is necessary to adjust the sour taste in the beverage by adding sugars such as xylitol in the future, so that it can be accepted by more consumers. Due to hydrolysis of glycan and oligosaccharidesacharide by enzymes secreted by _L. plantarum_, only sucrose, glucose, and fructose were selected for determination in the R-B mixed juice before and after fermentation in this study [40]. The viable cell count of the beverage fermented by _L.