## 3 Results and Discussion
### Estimating Antimicrobial Effectsof COS on Known Wine spoilage Microorganisms  
As COS showed greater antimicrobial effects than SO\({}_{2}\) on our own separated wine spoilage microorganisms, including six types of bacteria and three types of fungi, its antimicrobial effects onknown wine spoilage microorganisms were also evaluated. Among known wine spoilage  
\begin{table}
\begin{tabular}{c c c} \hline
**Additive** & **Concentration (mg/L)** & **Colony Count (CFU/mL)** \\ \hline / & / & \((2.17\pm 0.32)\times 10^{7}\) \\ COS & 500 & \((1.73\pm 0.57)\times 10^{4}\) \\  & 50 & \((1.86\pm 0.21)\times 10^{7}\) \\ SO\({}_{2}\) & 100 & \((1.34\pm 0.31)\times 10^{4}\) \\  & 200 & \((1.43\pm 0.38)\times 10^{3}\) \\ \hline \end{tabular}
\end{table}
Table 2: Comparative analysis of antimicrobial effects on the mixture of different wine spoilage organisms among using 500 mg/L COS and 50, 100, and 200 mg/L SO\({}_{2}\) as additives.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Colony Count (CFU/mL)**} \\ \cline{2-4}
**Wine spoilage Organisms** & **No COS** & **500 mg/L COS** & **100 mg/L SO\({}_{2}\)** \\ \hline _Enterococcus_ & \((1.81\pm 0.39)\times 10^{3}\) & \((6.60\pm 2.05)\times 10^{2}\) & \((1.6\pm 0.47)\times 10^{2}\) \\ _Bacillus cereus_ & \((1.49\pm 0.62)\times 10^{3}\) & \((5.90\pm 1.93)\times 10^{2}\) & \((6.33\pm 0.30)\times 10^{2}\) \\ _Paenibacillus_ & \((2.14\pm 1.01)\times 10^{3}\) & \((3.20\pm 1.06)\times 10^{2}\) & \((5.50\pm 3.69)\times 10^{2}\) \\ _Alkaliphilus_ & \((1.94\pm 0.37)\times 10^{3}\) & \((1.92\pm 0.74)\times 10^{2}\) & \((5.20\pm 2.28)\times 10^{1}\) \\ _Pantoa_ sp. & \((1.10\pm 0.20)\times 10^{2}\) & \((3.33\pm 1.52)\times 10^{1}\) & \((4.96\pm 1.30)\times 10^{1}\) \\ _Lactococcus_ & \((1.77\pm 0.52)\times 10^{4}\) & \((1.83\pm 0.09)\times 10^{2}\) & \((9.03\pm 0.22)\times 10^{3}\) \\ _Aspergillus flavus_ & \((1.39\pm 0.16)\times 10^{3}\) & \((6.56\pm 2.81)\times 10^{2}\) & \((9.96\pm 2.25)\times 10^{2}\) \\ _Aureobisidium pullulans_ & \((7.10\pm 3.11)\times 10^{3}\) & \((2.10\pm 0.71)\times 10^{2}\) & \((2.33\pm 0.45)\times 10^{2}\) \\ _Penicillium_ & \((1.63\pm 0.45)\times 10^{3}\) & \((2.26\pm 0.59)\times 10^{2}\) & \((8.13\pm 0.15)\times 10^{2}\) \\ \hline \hline \end{tabular}
\end{table}
Table 3: Comparative analysis of antimicrobial effects on nine different wine spoilage organisms between using 500 mg/L COS and 100 mg/L SO\({}_{2}\) as additives.  
microorganisms [33], _Pediococcus damnosus_, _Acetobacter aceti_, _Lactobacillus plantarum_, and _Lactobacillus brevis_ were selected for evaluation. As shown in Table 4, the colony counts of spoilage microorganisms grew during the first few days and then dropped rapidly owing to the increasing ethanol content. Neither SO\({}_{2}\) nor COS completely killed the microbes, but an inhibited microbe growth was observed. As ethanol resistance was different among these four wine spoilage microorganisms, their survival times during fermentation were different. The growth curve of each type of bacteria with 500 mg/L COS was always slightly below those with 100 mg/L SO\({}_{2}\) and far below those with no additive, as determined by the colony count from each time point (Table 4). Therefore, 500 mg/L COS showed stronger antibacterial effects comparable to 100 mg/L SO\({}_{2}\).