Natural antimicrobial compounds and their roles in improving food safety, security, and quality

Abstract

Food systems are nutrient-dense materials made up of macromolecules and small molecules. The different classes of macromolecules include carbohydrates, proteins, and lipids. The small molecules within food systems include vitamins, minerals, colors, flavor compounds, free monosaccharides, free amino acids, and free fatty acids. Chemically, foods are complex colloidal systems where the macromolecules are arranged in the form of emulsions, foams, gels, and sols. Food systems are also prone to extreme microbial degradation due to the growth of different types of microorganisms including spoilage and pathogens. As per the US Centre for Disease Control and Prevention, the top five microbes causing foodborne illnesses include Norovirus, Salmonella spp., Clostridium perfringens, Campylobacter spp., and Staphylococcus aureus. The leading microbes responsible for hospitalizations include Salmonella (non-typhoidal), Norovirus, Campylobacter spp., Toxoplasma gondii, and Escherichia coli O157: H7. The major microbes which cause death through food systems include Salmonella (non-typhoidal), Toxoplasma gondii, Listeria monocytogenes, Norovirus, and Campylobacter spp. In order, to protect food systems, different types of food processing technologies are available including high temperature, high pressure, pulsed electric field, ultrasound, atmospheric cold plasma, and radio frequency processing. However, these techniques are very expensive and require extensive maintenance costs. Therefore, in order to protect food systems, novel approaches need to be applied. One viable option is by the use of natural antimicrobial compounds. These antimicrobial agents can be classified based on their source: plant-based and animal-based. The important plant-based antimicrobial agents include flavonoids, polyphenols, terpenes, alkaloids, coumarins, polysaccharides, essential oils, antimicrobial peptides, saponins, anthraquinones, and organic acids. The major antimicrobial compounds obtained from animal sources include lactoperoxidase, lactoferrin, and lysozyme. Flavonoids are a class of physiologically active substances that possess bacteriostatic and antioxidant properties. Flavonoids can be classified into flavones, flavonols, dihydroflavonoids, isoflavones, and double flavonoids. The polyphenols family includes a host of molecules include flavonoids, phenolic acids, chromones, tannins, lignin, quinine, procyanidin, catechin, curcumin, tea polyphenols, and apple polyphenols. The terpene groups include different types of molecules such as isoprene, monoterpene, diterpene, hemiterpene, steroid, carvacrol, linalool, acetate, and piperitone. Alkaloids can be divided into various groups, including isoquinolines, quinolines, indoles, piperidines, terpenes, steroids, and more. Coumarins can be divided into several groups such as simple coumarins, furocoumarins, furocoumarins, and other coumarins. Some of the promising polysaccharides that demonstrate antimicrobial activities include alginate, fucoidan, and kelp polysaccharides. Essential oils are a diverse group of molecules that exhibit broad-spectrum antimicrobial activity which includes chemical groups such as ketones, aldehydes, esters, ethers, acids, and lactones. Some of the important essential oil components include thymol, eugenol, carvacrol, cinnamaldehyde, limonene, geraniol among many other molecules. The major antimicrobial peptides of plant-based sources include defensins, lipid transfer proteins, snakins, heveins, knottins, cyclotides, and thionins. Our lab has primarily focused on the synthesis, characterization, and application of biodegradable food packaging systems functionalized with antimicrobial agents from plant sources. A major focus of our research has been directed towards the application of essential oils in the preparation of such bioactive food packaging systems. The application of plant and animal-derived antimicrobial compounds can serve as robust materials for the overall improvement of food safety, security, and quality.