## 3 Essential Oils, Terpenes and Terpenoids in Agrifood  
The constantly increasing worldwide need for food and the consequent necessity for well-preserved crops and edibles have dictated the need to seek effective, sustainable, and biocompatible preservation methods. Currently, essential oils (EOs) have emerged as a highly promising alternative. Their antimicrobial properties enable them to effectively address issues caused by pests, weeds, fungi, and bacteria without harming  
Figure 2: Toxicity of organic ligands and corresponding MOFs based on Fe, based on IC\({}_{50}\) data [110,114] Reprinted with permission from Ref. [110] ©Elsevier 2023.  
crops or causing bioaccumulation, a significant concern with commonly used chemical synthetic compounds. More specifically, EOs are secondary metabolites produced by various plants in order to survive under extreme environmental conditions, such as high or low temperatures and non-optimal pH levels. These oils are rich in bioactive low molecular weight compounds, such as terpen, aldehydes, ketones, esters, oxides, and alcohols (Figure 3) [113]. The chemical composition of EOs varies significantly across plant families and even within the same species, according to external environmental factors [116]. For centuries, EOs are known for their antimicrobial properties and for this they have been studied in depth. Their diverse chemical nature enables them to be effective against various pathogens, such as bacteria, fungi, and viruses. For example, thyme (_Thymus vulgaris_) [117], oregano (_Origanum vulgare_) [118], and cinnamon (_Cinnanomum zeylanicum_) are known for their antibacterial [119] and antifungal activities [120]. This antimicrobial activity can be attributed to EOs' ability to disrupt cell membranes, interfere with ion transport within microorganisms, and induce leakage of cellular contents, that leads to cell death [68; 69; 121]. Furthermore, due to their natural origin, EOs do not present the risk of bioaccumulation, and for this reason the GRAS (Generally Recognized As Safe) status by the United States Food and Drug Administration has been attributed to them, making them a promising alternative in various agrifood sectors, including food preservation and sustainable biopesticles [122]. However, despite their potential, several challenges hinder their wider application as antipathogenic agents. To name a few, their intense aroma, high volatility, hydrophobicity, and potential interactions with food components can negatively impact organoleptic properties [123]. Additionally, their instability and limited solubility reduce their effectiveness as preservatives. It is important to note that in agricultural applications, biomass availability, chemical stability, formulation, and phytotoxicity present significant obstacles [124]. Figure 3: Bioactive low molecular weight components of Essential Oils. These promising characteristics necessitate scientific efforts to overcome these limitations, offering safe, economical, and environmentally friendly alternatives that address health hazards and contribute to food security in the face of a growing global population. To mitigate these challenges, advanced delivery strategies such as nanoencapsulation, active packaging, and polymer-based coatings have been developed. Through these methods the EO stability is enhanced along with solubility, and controlled release, improving bio-efficacy and minimizing impacts on food sensory attributes [73; 74]. In agriculture, novel application methods have been introduced. For example, seed coating with EOs, has demonstrated potential for inducing durable plant defenses with long-term effects using small amounts of EOs [124]. The aforementioned inherent challenges associated with the wider utilization of EOs, primarily their volatility and chemical instability, can be effectively addressed through encapsulation within porous materials. This route offers a multifaceted approach to enhancing the applicability of EOs across various sectors including that of agrifood.