*5.6. Nanoprecipitation*

The process of hydrophobic component encapsulation using the nanoprecipitation (solvent displacement or interfacial deposition) technique involves first dissolving the essential oil in an organic solvent together with the polymers. The solution is then added to the water that is being stirred at the proper speed. The solution is then supersaturated, nucleated, and then it expands and coagulates [125]. This technique is suitable during post-harvest to increase the insecticidal efficiency against stored-grain insect pests [126]. There is, however, limited study on insect pest control during post-harvest and handling of tropical fruits.

Tangpao et al. [66] studied the Oriental fruit fly-attracting ability of methyl eugenol plant-based essential oils and encapsulated the oil using an adapted complexation with the paste method of different wall materials. The holy basil essential oil was found to have the ability to attract the Oriental fruit flies, and encapsulation with maltodextrin and gum Arabic at a ratio of 75:25 could enhance its effectiveness in attracting the flies in mango orchard. For this purpose, the paste method is the economical and straightforward technique to encapsulate the essential oil using the chemical and mechanical reaction between the core and wall materials [127]. In addition, the encapsulation of basil essential oil by freeze-drying technique is encouraged to prevent the loss of such heat-sensitive active volatiles that are unstable in aqueous solution [128].

The antimicrobial properties of essential oils have led to research interest in their applications during the post-harvest and storage of fruits. However, the downside is that the strong scents from essential oils could interfere with the true aroma of the produce. This is generally mitigated by the nanoemulsion technique with sodium alginate or pectin-based edible coating and the high-pressure homogenisation technique [112]. All in all, several considerations should be taken into account when applying the essential oil in agricultural productions, such as its volatilisation nature [129] and the activity losses due to the exposure to ultraviolet light, temperature, humidity, and oxygen [130]. More importantly, the releasecontrol rate of the products needs to be investigated [131,132]. Scheme 1 illustrates the possible encapsulation approaches to increase the efficiency of the essential oil during tropical fruit production.

**Scheme 1.** Enhancing the efficiency of basil volatile organic compounds during pre- and postproduction of the tropical fruits.
