*4.6. Vitamin C*

Vitamin C is classified as a natural antioxidant compound and has a potential role in reducing the risk of cancer by scavenging ROS in the human body [50]. However, vitamin C is rapidly degraded in fresh fruit and vegetables by several factors including storage [17]. Therefore, there is a need to minimize the decrease in vitamin C during refrigerated storage. Our results showed that the applied treatments of essential oil, ethanol and AsA presented a higher vitamin C value only towards the end of the storage period (9 and 12 d) The same results have been observed in previous studies for treated loquat fruit [18] with ethanol and litchi fruit with AsA [40].

The effect of postharvest treatment of TTO on vitamin C content of fruit and vegetable is not identified well due to limited research on this application. For example, a higher concentration of vitamin C was observed in lettuce plants treated before harvest with TTO

and stored for 20 d at −2 ◦C [51]; however, it was mentioned that no significant difference was observed after 3 d of storage. The difference in our study could be due to the difference in time of application and different concentration of TTO, also due to the difference in plant spices.

Our results shown in Figure 2A are in concurrence with previous work by Naeem et al. [48], who found that application of PMO acting as a semi-permeable coating around the samples' surfaces resulting in a reduction of vitamin C loss. The reduction in vitamin C loss by EOs application could be explained by the antioxidant properties of EOs resulting in a reduction in oxygen diffusion and respiration rate [52].
