## 3 Results and Discussion
### Post-Harvest Evaluation of Citral-Treated Table Grapes during Storage  
The sensory evaluation of VQ was not significantly affected by citral treatment on each storage day, although, during the experiment, a significant reduction in VQ was scored in all treatments, as a consequence of decay. As for the citral odor perception in fruits, it was highly perceived in the treated fruits after 15 days (mean score of about 4), whereas, at the end of storage, a lower odor score was attributed (mean score around 3) to the treated samples. Anyway, the perception of citral was notable only after the opening of the bags, after which (around 30 min at air) the citral odor was lost. Regarding the determination of citral in the head space of the plastic trays containing the table grape samples, the HS-SPME/GC-MS method allowed us to evaluate the concentrations of two isomeric forms of citral, i.e., (Z)-citral and (E)-citral, in the head space of the plastic trays containing the grape samples. A reduction in the content of (Z)-citral and (E)-citral of 62 and 58%, respectively, was observed after only 1 day of storage for the samples treated with 0.0125 \(\upmu\)L/cm\({}^{3}\). An almost total reduction (99%) in both molecules was registered after 15 storage days, even if their presence was perceived by the panelists because of the gas diffusion into the plant tissue. In the case of samples treated with 0.05 \(\upmu\)L/cm\({}^{3}\), a lower reduction in citral content with respect to samples treated with 0.0125 \(\upmu\)L/cm\({}^{3}\) was observed. Specifically, a reduction in (Z)-citral of 27, 40, and 79% at 1, 7, and 15 sampling days was measured. Similarly, it was observed a decrease in (E)-citral of 29, 56, and 83% on the same sampling days. These results indicate that, by using 0.05 \(\upmu\)L/cm\({}^{3}\), a higher content of both isomers of citral was found in the head space of the used plastic tray. It is worth underlining that citral was found as one of the main compounds detected in seedlings grapes at the end of ripening [51] and this could increase the acceptability by the consumer. However, the sensory attributes of other fruits stored in packaging functionalized with citral were not affected by treatment [52; 53]. Overall, the decay incidence recorded in the treated samples was significantly lower than that of the control grape samples (\(p<0.05\)), regardless of the applied citral doses (Figures 2 and 3). Starting from day 10 of storage, in berries treated with 0.0125 \(\upmu\)L/cm\({}^{3}\), rotting increased by reaching 25.5% of incidence, on average, at the end of the trial; the treatment with the highest citral dose resulted in values significantly (\(p<0.05\)) lower than those registered with the lowest dose (incidence of rot by 3.6 and 17.2% at days 10 and 15 of incubation, respectively) (Figure 2). By contrast, the control sample showed rotting that linearly increased with storage time and reached average decay percentages of 64.2% already from day 5. Quite similar values were previously reported in table grapes treated with modified atmosphere packaging (MAP) in combination with eugenol or thymol concentrations higher than those used in the present work [54]. As expected, _R. oryzae_ ITEM 18876 growth in the untreated samples showed slight increments at 12 \({}^{\circ}\)C (Figure 4); however, the counts of _R. oryzae_ ITEM 18876 on the inoculated grape clusters and alternatively treated with the two citral doses were, on average, lower than those registered for the control clusters over the period of incubation. Indeed, simple main effects showed that both doses of citral had a higher and significant (\(p<0.001\)) inhibitory effect on _R. oryzae_ viability starting from day 10 in comparison to the control samples (Figure 4). In addition to that demonstrated for other fruits [55], our results confirm the efficacy of the low doses of citral also in counteracting _R.