*4.2. Post-Harvest Applications*

In addition to their potential to control pre-harvest insect pests, the influence of extracts from *Omimum* spp. plants on the control of post-harvest insect pests was also investigated (Table 4). It was discovered that the essential oils of basils (*O. basilicum* and *O. tenuiflorum*) had volatile toxicity against stored-grain pests such as *Sitophilus oryzae*, *Rhyzopertha dominica*, *Cryptolestes* pusillus, *Sitophilus zeamais*, *Tribolium castaneum,* and *Acanthoscelides obtectus* [16,17,91–93] as well as the stored dates pests (*Ectomyelois ceratoniae* and *Ephestia kuehniella*) [94]. The powder form of the dried sweet basil plant has been used to repel *Sitophilus zeamais* Motschulsky, a post-harvest pest causing considerable damage to maise grain in most stores in Africa [95]. In addition to its ability to control insects, the role of essential oils as a natural post-harvest fungicide was also well recognised. From previous studies, the vapour of essential oils has the potential to inhibit post-harvest microorganisms [96,97], such as the harvested avocado fruit disease fungus (*Cercospora purpurea*) [98] and the peach and nectarine disease fungus (*Monilinia laxa*) [99]. The substances with low molecular weight and low polarity of essential oil play a role in the loss of cell membrane integrity of the pathogen by altering the pH in the cell, thereby inhibiting the growth as well

as inducing programmed cell death [100]. The essential oils from *Ocimum* spp. were able to inhibit the fungi causing the post-harvest diseases of the tropical fruits [10,13,14,101]. This also includes *Colletotrichum* spp., the fungus that causes anthracnose disease in common tropical fruits. Linalool is the most active substance in the *O. basilicum* essential oil that could inhibit the diseases of the stored seeds of lettuce and tomatoes caused by *F. oxysporum*, *Penicillium* spp., and *C. gloeosporioides* [102]. The crown rot pathogens that infected cut bananas during farm-level handling and packhouses were positively controlled by the combination of aluminium sulphate and basil oil in the modified atmosphere packaging during cold storage (12–14 ◦C) [103].

**Table 3.** Uses of volatile organic compounds from the studied *Ocimum* species against pests of horticulture crops.


**Table 4.** Uses of volatile organic compounds from the studied *Ocimum* species during post-harvest managemen<sup>t</sup> of horticultural produce.




#### **5. Techniques for Enhancing the Essential Oil Efficiency**

Encapsulation is a widely used process for generating an external membrane or coating material that protects or preserves sensitive bioactive, volatile, and quickly degradable substances from biochemical and thermal degradation [104]. Encapsulation is a technique that is commonly used in the flavour and fragrance industries to enhance both taste and scent. This technology also increases the efficacy of pesticides, fertilisers, and other toxic agrochemicals in agriculture, thereby improving productivity and food security. The active substances are encapsulated to regulate the release under accurate conditions (e.g., humidity, temperature, pH, and time) and to be active for a specific object (e.g., organisms or parts of the organisms). Moreover, encapsulation in agriculture can minimise harmful chemicals [105,106] and increase the efficiency of the natural extracts' action [66]. The encapsulation can be performed by coating with the material, creating core materials, filing in the internal phase or payload, and the substance's characteristics can be pure or mixed.

The coating materials are packing material, capsule, wall material, film, membrane, carrier, or outer shell [107]. They are usually made of natural or modified polysaccharides, gums, proteins, lipids, and synthetic polymers [108]. The organic flavour and the aroma of interest are low molecular weight compounds that are relatively volatile and very sensitive to open conditions (air, heat, light, and moisture). Depending on the applied encapsulation technique, the encapsulated essential oil products can be in powder, paste, or liquid forms [109,110]. Numerous techniques are available for encapsulating essential oils for agricultural uses, depending on the nature of the environment in which the products are applied.
