Chemical Composition of Essential Oils and Their Potential Applications in Postharvest Storage of Cereal Grains

Insect infestation and microbial, particularly mold contamination, are the major causes of stored grain deterioration during postharvest storage, which results in a significant loss in grain quality and quantity, and the formation of toxic chemicals such as mycotoxins. Pesticides, together with physical protection strategies, have been widely used to control insects and molds in stored grains, but their uses present significant environmental and health problems. This has led to the exploration of safer pesticide alternatives. Essential oils (EOs) are highly concentrated materials extracted from leaves, stems, flowers, seeds, roots, fruit rinds, resins, or barks. They are multifunctional due to their complex chemical composition. Thus, EOs are frequently used for their therapeutic, antimicrobial, odoriferous, and flavor properties in a wide range of products like medicine, cosmetics, and foods. This review provides comprehensive information on the chemical compositions of EOs commonly used in the food industry, factors influencing EO composition, and recent studies on the potential of EOs as alternatives to synthetic pesticides and fungicides for stored grain protection. The relationship between chemical compositions of EOs and their anti-insects and antimicrobial potentials, as well as current approaches/technologies of using EOs for food preservation, are also covered. However, this review also highlights the need for research on the development of feasible and affordable methodologies to apply effective EOs or encapsulated EOs in grain storage settings, particularly for organic grain protection.