Hot water dipping treatments on Tarocco orange fruit and their effects on peel essential oil

Abstract

The most common and serious diseases which affect citrus fruit after harvest in Italy are induced by Penicillium digitatum Sacc. and Penicillium italicum Weh., responsible respectively for green and blue mold rots. This paper deals with the effectiveness of hot water dipping (HWD) treatments as alternative means to control postharvest decay on Tarocco orange fruit [Citrus sinensis (L.) Osbeck], and their effect on fruit quality with special regard to peel essential oils. Selected treatments were HWD at 52°C for 180s and at 56°C for 20s. These treatments were compared with an effective fungicide standard treatment (Imazalil) and an untreated control. The results showed that HWD at 56°C for 20s was more effective in inhibiting P. digitatum spore germination than HWD at 52°C for longer exposure time. In addition, HWD treatment at 56°C significantly increased the level of alcohols, esters and aliphatic (fatty) aldehydes. Therefore, the lowest values of decay incidence recorded in HWD fruit treated at 56°C may be due to the increase in oxygenated monoterpenes, esters and aldehydes. Finally, HWD treatments did not cause surface damage or color change and did not influence internal quality parameters.