## 2 Results and Discussion
### Changes in the Composition of Volatile Compounds in Strawberries
The concentration of 4-methoxy-2,5-dimethyl-3(2H)-furanone of bright-red strawberries (B0h, 156 \(\mathrm{\SIUnitSymbolMicro\text{$\text{$9\text{$ \text{$0\text{$ \text{$1\text{$ \text{$2 \text{$ \text{$3\text{$ \text{$4\text{$ \text{$5\text{$ \text{$6\text{$ \text{$7\text{$ \text{$8\text{$ \text{$9\text{$\text{$0\text{$\text{$1}$\text{$2}$\text{$3}}}}}}}}}}\)/kg) increased 35.3-folds after 9 d storage (B9D, 1,137 \(\mathrm{\SIUnitSymbolMicro\text{$\text{$4\text{$\text{$5\text{$\text{$6\text{$\text{$7 \text{$\text{$8\text{$\text{$9\text{$\text{$0\text{$\text{$1\text{$\text{$2 $\text{$3\text{$\text{$4\text{$\text{$5\text{$\text{$6}$\text{$7}$\text{$8}}}}}}}}}\)/kg). For the CO\({}_{2}\) treatment groups, the 4-methoxy-2,5-dimethyl-3(2H)-furanone concentrations also increased but were lower compared to the control groups (H9D (711 \(\mathrm{\SIUnitSymbolMicro\text{$\text{$9\text{$\text{$0\text{$\text{$1\text{$\text{$2\text{$\text{$3\text{$\text{$4\text{$\text{$5\text{$\text{$6\text{$\text{$7\text{$\text{$8\text{$\text{$9\text{$}}$0\text{$}}$1 $}}$2}$}}$3}$}}$4}}}}}}}}}\)/kg\) vs. HT9D (411 \(\mathrm{\SIUnitSymbolMicro\text{$}}$5\text{$}}$6\text{$}}$7\text{$}}$8 \text{$}}$9\text{Figure 3.00\text{Figure 3.01\text{Figure 3.02\text{Figure 3.03 Figure 3.04\text{Figure 3.05\text{Figure 3.06\text{Figure 3.07}}}}}Figure 3.08}Figure 3.09}Figure 3.10}}}}}}}\)/kg); B9D (1,137 \(\mathrm{\SIUnitSymbolMicro\text{Figure 3.11\text{Figure 3.12\text{Figure 3.13\text{Figure 3.14 \text{Figure 3.15\text{Figure 3.16\text{Figure 3.17\text{Figure 3.18\text{Figure 3.19 Figure 3.20\text{Figure 3.21Figure 3.22\text{Figure 3.23}}}}Figure 3.24}Figure 3.25}Figure 3.26\text{Figure 3.27\text{Figure 3.28\text{Figure 3.29\text{Figure 3.30 \text{Figure 3.31\text{Figure 3.32\text{Figure 3.33\text{Figure 3.34\text{Figure 3.35 Figure 3.36\text{Figure 3.37\text{Figure 3.38\text{Figure 3.39}Figure 3.40}}Figure 3.41}}}}}}}}}\)/kg)). Thus, CO\({}_{2}\) treatment may inhibit the production of 4-methoxy-2,5-dimethyl-3(2H)-furanone during storage. High CO\({}_{2}\) treatment of strawberries may induce a decrease in alcohol acetyltransferase activity, which is responsible for ester biosynthesis from acetyl CoA [33]. Thus, short-term CO\({}_{2}\) treatment of half-red and bright-red strawberries may inhibit the production of esters during storage. In a previous study, CO\({}_{2}\) treatment of strawberries inhibited  
Figure 3.42 Comparisons of relative concentrations of characteristic volatile compounds in control and CO\({}_{2}\)-treated strawberries at varying stages of ripening stored at 10 \(\mathrm{\SIUnitSymbolCels  
the production of glucose, which is a carbon source for 4-hydroxy-2,5-dimethyl-3(2H)-furanone [34; 35]. The concentrations of furanones, such as 4-methoxy-2,5-dimethyl-3(2H)-furanone, increased during postharvest ripening possibly because of an increase in _Fragaria \(\times\) ananassa_ O-methyltransferasef transferase (FaOMT) activity that changes methylated 4-hydroxy-2,5-dimethyl-3(2H)-furanone into 4-methoxy-2,5-dimethyl-3(2H)-furanone [36; 37]. Thus, CO\({}_{2}\) treatment may also inhibit furanone accumulation during storage by decreasing the glucose concentration, which is responsible for furanone biosynthesis and decreasing FaOMT activity during storage. Acetaldehyde is responsible for the pungent aroma, which is the off-odor in strawberries [38]. The acetaldehyde concentration of half-red strawberries (H0h, 899 \(\upmu\)g/kg) was similar to that of bright-red strawberries (B0h, 881 \(\upmu\)g/kg). The acetaldehyde concentration of half-red strawberries (H0h, 899 \(\upmu\)g/kg) increased after 9 d of storage (H9D, 986 \(\upmu\)g/kg). In the case of bright-red strawberries, the acetaldehyde concentration (B0h, 881 \(\upmu\)g/kg) increased after 9 d of storage (B9D, 988 \(\upmu\)g/kg). The acetaldehyde concentration of H9D (986 \(\upmu\)g/kg) was 2.0-fold higher than that of HT9D (505 \(\upmu\)g/kg). The acetaldehyde concentration of B9D (988 \(\upmu\)g/kg) was 2.2-fold higher than that of BT9D (440 \(\upmu\)g/kg).