Application of Lavender and Rosemary Essential Oils (EOs), Their Mixture and Eucalyptol (EOs Main Compound) on Cucumber Fruit Quality Attributes and Microbial Load

Abstract

Cucumber (Cucumis sativus L.), one of the most widely consumed vegetables, presents high perishability during storage and marketing if it is not handled and stored properly. Currently, there is an increased interest of the food industry to reduce waste (due to quality losses) and to utilize natural products for the preservation of fresh commodities. This study’s goal was to evaluate the effects of lavender (Lav) and rosemary (Ros) essential oils (EOs), their mixture (Lav + Ros, 1:1 v/v) and their main compound (eucalyptol) via vapor phase on cucumber’s postharvest quality. The outcomes of this study demonstrated that 200 μL/L of Lav and Ros EOs increased the respiration rate of cucumbers after 10 days of storage at 11 °C, while 100 μL/L of the EOs mixture and Eucalyptol (100 and 200 μL/L) had no effect on respiration, on the same day. The application of Eucalyptol (100 and 200 μL/L) resulted in less acceptable fruits (less pleasant aroma and unpleasant taste). A decrease in fruit firmness was found in cucumbers exposed to Lav 200 μL/L and Ros 100 μL/L. Interestingly, Eucalyptol was found to accelerate the fruit ripening index after five days of storage, and to decrease organoleptic properties of the fruit (i.e., aroma, taste) on the fifth day of storage. The fruit revealed increased oxidative stress (i.e., increased lipid peroxidation), especially at a high concentration (200 μL/L) of Eucalyptol after 10 days. This has resulted in the activation of other non-enzymatic antioxidant mechanisms such as the increase in fruit ascorbic acid content. Notably, no effects on fruit weight loss, total soluble solids and color were observed with the examined treatments. Overall, this study suggests that the investigated products (EOs and their main compound) have a putative role in postharvest storage for the preservation of cucumbers. However, further investigation is needed for the determination of the optimum application conditions (i.e., concentration, time and method of application) on cucumbers and other fresh produce.