# Marination as a Hurdle to Microbial Pathogens and Spoilers in Poultry Meat Products: A Brief Review
## 3 Antimicrobial Activity of Natural Compounds
### Essential Oils and Extracts from Aromatic Herbs  
Although most studies reporting the antimicrobial activity of aromatic herbs delve into EOs, studies employing plant extracts have also been conducted. However, there is still a lack of knowledge on how the extraction processes affect the bioactivity of most aromatic plant extracts. Nonetheless, the plant extracts from common aromatic herbs such as oregano and thyme have shown antimicrobial activity against foodborne pathogens and spoilage bacteria. [PERSON] et al. (2021) studied the inhibitory and bactericidal activity of two polyphenich wild thyme extracts against seven foodborne pathogens. Of all the tested bacteria, _Enterococcus faecalis_ was the most susceptible to inhibition from the tested extracts, with a minimum inhibitory concentration (MIC) of 0.313 mg/mL. Moreover, _L. monocytogenes_ and _Bacillus cereus_ presented the highest tolerances, with MIC values of 0.625 mg/mL for both organisms. _Staphylococcus aureus_ and _Yersinia enterocolitica_ were considerably less susceptible to the inhibitory effect of the wild thyme extracts (MIC 1.25 mg/mL). Regarding the bactericidal effect, _L. monocytogenes_ proved to be the most susceptible of all the tested microorganisms, with a minimum bactericidal concentration (MBC) of 2.5 mg/mL. On the other hand, _S. aureus_ and _Y. enterocolitica_ showed the highest resistance to the extracts, with an MBC value of 10 mg/mL ([PERSON], 2013). [PERSON] et al. (2013) evaluated the antimicrobial activity of oregano extracts and the EOs obtained through hot water extraction against seven foodborne pathogens and spoilage bacteria. The tested extracts inhibited the growth of the tested bacteria. Nonetheless, the EOs inhibited the growth (MIC value \(<\) 5 mg/mL) and reduced the levels of the tested microorganisms ([PERSON], 2013). Essential oils are volatile and aromatic oily liquids extracted from plant components (e.g., leaves or seeds, fruits, stems, roots, and buds) and possess hundreds of low molecular weight secondary metabolites ([PERSON], 2013). Among all the compounds in EOs, we can distinguish two noteworthy classes of active compounds: terpenes and phenols. Although terpenes and terpenoids are the most prevalent class in EOs (KThe mechanisms behind the antimicrobial activity of EOs vary, either leading to a bacteriostatic effect, where the bacterial growth inhibition occurs, or to a bactericidal action, where EOs kill the bacterial cells. Essential oils most commonly target the cytoplasmic membrane, damaging it while disrupting efflux pumps and other proteins embedded into the cell membrane, leading to leakage of intracellular components and subsequent membrane rupture and cell death [2; 79]. Carvacrol, thymol, and garlic extracts were shown to exert this mechanism of antimicrobial action [80; 81]. Essential oils can also exhibit antibacterial activity through other means. For instance, andrographolide, a terpene, can interfere with protein and DNA synthesis [82], while quercetin inhibits the biosynthesis of unsaturated fatty acids [83]. The United States Food and Drug Administration (FDA) classifies several EOs as generally recognised as safe (GRAS). However, as with any other compound, using EOs as antimicrobials in meat products has certain limitations. Meat is a complex matrix that encompasses high quantities of saturated fatty acids and proteins, which may decrease the activity of EOs due to their high binding capacity of volatile compounds present in the EO. Consequently, they lead to the need to administer higher concentrations of EOs in meat products, raising another question; adding high concentrations of EOs to meat products creates powerful and unpleasant aromas and off-flavours, making them unacceptable to the consumer. The use of EOs in edible coatings, active packaging, microencapsulation, and nanoparticles has been proposed [84; 85; 86; 87].