With the recent trend toward “clean” eating—choosing food products that contain no chemical additives like artificial colors, flavors, thickeners, or preservatives—essential oils have found significantly increased popularity among food manufacturers and packagers. Not only do consumers perceive essential oils to be natural, but most of the major bottlers and marketers of the oils in the United States take the step of certifying them as organic by the U.S. Department of Agriculture (USDA), making them appropriate for use in products labeled as “natural” or organic.
Essential oils can be found in the ingredient lists for many candies, chewing gums, ice creams, baked goods, pudding, gelatins, chocolates, frostings, marinades, salad dressings, herbal teas, and even soups and other canned products. These oils are not packaged in the same way as the ones consumers buy for aromatherapy: they have nutritional information on their bottles, a requirement for any ingredient to be used in the food processing industry. They also may contain vegetable glycerin or propylene glycol, organic compounds that make them easier to blend into foods on the scale of a manufacturing and packaging facility. This does not make the oils any less organic or natural—it simply adapts them to the needs of the industry. The FDA supplies food manufacturers with instructions for the use of each oil, including how much of the oil is safe as a food additive and which oils can be used in this manner.
Essential oils packaged for use in food in consumer households are available from selected essential oil bottlers (LorAnn Oils is the best known of these), and they come with specific instructions for their use in food, to be sure that consumers do not overuse the oil and end up with unpleasant results.
Recently, the food manufacturing industry has made significant investments in research to determine if any of the claims about essential oils’ antimicrobial properties could be true. The results have led some food packagers to begin replacing synthetic preservatives with specific essential oils that have shown promise. A list of oils grown and harvested in Italy and tested by Pellegrini et al. (2018) turned up some “interesting biological potentiality,” suggesting that they may be candidates for “natural biopreservatives,” with coriander, fennel, garlic, oregano, peppermint, rosemary, salvia, savory, and thyme in the lead for this. A study (Ballester-Costa et al., 2017) found that of the many varieties of thyme essential oil on the market, two species—Thymus zygis and Thymus capitatus—demonstrated antibacterial activity when tested on beef. Hsouna et al. (2017) found that citrus lemon essential oil showed antioxidant activity against Listeria monocytogenes bacteria in beef and actually inhibited the bacteria’s development.
A study by Houda Banani et al. (2018) discovered that apples treated with thyme or savory essential oils showed resistance to a gray mold, Botrytis cinerea, a common nuisance in the apple industry. Banani concluded that the oils sparked the apple’s own defenses against the mold, making it produce a gene to protect itself. Additional research on thyme and savory oils by Santoro et al. (2018) found that treating peaches and nectarines with a vapor containing these two oils could control brown rot, improving the storage quality of the fruit.
A study (Nowotarska et al., 2017), published in the journal Foods, examined the antimicrobial abilities of cinnamon and oregano essential oils against Mycobacterium avium paratuberculosis, a pathogen that infects both livestock and humans and is found in milk, cheese, and meat. The study determined that the oils targeted the cell membrane of the pathogen to begin the destruction of the bacteria, providing insight into how these essential oils’ antimicrobial properties work. This could be a useful step in determining if these and other oils can be useful as food preservatives.
So why not just throw out all the chemical preservatives and use essential oils instead? The transition is not so simple as that, because food production uses heat, light, and air—three things that can degrade essential oils rapidly and rob them of their effectiveness. The industry continues to explore ways to make use of the oils’ antimicrobial properties, including actually adding the oils to the food packaging rather than to the recipes. Creating edible films and coatings that protect the food with their antioxidant and antimicrobial properties may be one solution, especially if such a thing takes nothing away from the flavor or appearance of the food itself. Research is ongoing, with new discoveries and innovations expected.