Look up “essential oils” on the Internet and you mostly get sites about aromatherapy. Wikipedia states, “An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetherolea, or simply as the ‘oil of’ the plant from which they were extracted, such as oil of clove. An oil is ‘essential’ in the sense that it contains the characteristic fragrance of the plant from which it is taken. Essential oils do not form a distinctive category for any medical, pharmacological, or culinary purpose. They are not essential for health.” Essential oils may not be essential for health, but they are proving to have benefits when it comes to keeping food safer to eat.
“Have you ever taken a bite into one of your favorite foods just to regret it later, as your stomach cramped up from food poisoning?” asks Erica Robinson. “Foodborne illness is very common,” she adds, “especially when handling and eating raw foods. One in six people every year get food poisoning in the United States. The good news is that researchers have found that cinnamon might reduce the chances of developing these illnesses.” [“Cinnamon Cassia Oil’s Antibacterial Properties Make It Good For Preventing Foodborne Illness,” Medical Daily, 19 July 2014] She explains:
“A new study conducted by two Washington State University scientists shows that just a few drops of cassia cinnamon oil can kill harmful pathogenic bacteria in as little as 24 hours. ‘The oil can be incorporated into films and coatings for packaging both meat and fresh produce,’ said co-author Lina Sheng, a graduate student in the School of Food Science, in a press release. ‘It can also be added into the washing step of meat, fruits, or vegetables to eliminate microorganisms.’ The study found that the oil was able to kill the top six strains of Shiga toxin-producing Escherichia coli (STEC). The study was part of an effort to find natural ways of eliminating pathogens from food.”
Cassia oil is derived from the Chinese cinnamon, an evergreen tree originating in southern China, and widely cultivated there and elsewhere in southern and eastern Asia (India, Indonesia, Laos, Malaysia, Taiwan, Thailand, and Vietnam). But it is not the only essential oil being researched for its anti-pathogenic properties. Farm and Dairy reports that researchers from the College of Agricultural Sciences at Penn State are also experimenting with essential oils in packaging. “Using films made of pullulan — an edible, mostly tasteless, transparent polymer produced by the fungus Aureobasidium pullulans — researchers evaluated the effectiveness of films containing essential oils derived from rosemary, oregano and nanoparticles against foodborne pathogens associated with meat and poultry.” [“Research suggests antimicrobial edible films inhibit pathogens in meat,” 17 June 2014] Like the Washington State University research, scholars at Penn State are looking at essential oil use in both packaging and food preparation. Catherine Cutter (@drkitty92), a professor of food science at Penn State, stated that the results of their work demonstrated that “bacterial pathogens were inhibited significantly by the use of the antimicrobial films. … She hopes the research will lead to the application of edible, antimicrobial films to meat and poultry, either before packaging or, more likely, as part of the packaging process.” Cutter’s methodology is described below:
“In the study, which was published online in the Journal of Food Science, researchers determined survivability of bacterial pathogens after treatment with 2 percent oregano essential oil, 2 percent rosemary essential oil, zinc oxide nanoparticles or silver nanoparticles. The compounds then were incorporated into edible films made from pullulan, and the antimicrobial activity of these films was determined against bacterial pathogens inoculated onto petri dishes. Finally, fresh and ready-to-eat meat and poultry products were experimentally inoculated with bacterial pathogens, treated with the pullulan films containing the essential oils and nanoparticles, vacuum packaged and evaluated for bacterial growth following refrigerated storage for up to three weeks. ‘The results from this study demonstrated edible films made from pullulan and incorporated with essential oils or nanoparticles have the potential to improve the safety of refrigerated, fresh or further-processed meat and poultry products,’ said Cutter. ‘The research shows we can apply these food-grade films and have them do double duty — releasing antimicrobials and imparting characteristics to protect and improve food we eat.’”
Phakawat Tongnuanchan and Soottawat Benjakul are also studying how essential oils can be used to extend the shelf-life of the foods we eat. In the abstract for their paper, which was published in the Journal of Food Science, they wrote, “Essential oils are a good source of several bioactive compounds, which possess antioxidative and antimicrobial properties. In addition, some essential oils have been used as medicine. Furthermore, the uses of essential oils have received increasing attention as the natural additives for the shelf-life extension of food products, due to the risk in using synthetic preservatives. Essential oils can be incorporated into packaging, in which they can provide multifunctions termed ‘active or smart packaging.’ Those essential oils are able to modify the matrix of packaging materials, thereby rendering the improved properties.” [“Essential Oils: Extraction, Bioactivities, and Their Uses for Food Preservation,” Journal of Food Science, 2 June 2014] Tongnuanchan and Benjakul provide the following table showing which parts of plants are used to produce essential oils.
|Leaves||Basil, bay leaf, cinnamon, common sage, eucalyptus, lemon grass, citronella, melaleuca, mint, oregano, patchouli, peppermint, pine, rosemary, spearmint, tea tree, thyme, wintergreen, kaffir lime, laurel, savory, tarragon, cajuput, lantana, lemon myrtle, lemon teatree, niaouli, may chang, petitgrain, laurel, cypress|
|Seeds||Almond, anise, cardamom, caraway, carrot celery, coriander, cumin, nutmeg, parsley, fennel|
|Wood||Amyris, atlas cedarwood, himalayan cedarwood, camphor, rosewood, sandalwood, myrtle, guaiac wood|
|Bark||Cassia, cinnamon, sassafras, katrafay|
|Flowers||Blue tansy, chamomile, clary sage, clove, cumin, geranium, helichrysum hyssop, jasmine, lavender, manuka, marjoram, orange, rose, baccharises, palmarosa, patchouli, rhododendron anthopogon, rosalina, ajowan, ylang-ylang, marjoram sylvestris, tarragon, immortelle, neroli|
|Peel||Bergamot, grapefruit, kaffir lime, lemon, lime, orange, tangerine, mandarin|
|Root||Ginger, plai, turmeric, valerian, vetiver, spikenard, angelica|
|Fruits||Xanthoxylum, nutmeg, black pepper|
They note that the use of essential oils in the food industry is limited because they can change the taste and smell of some foods. “Essential oils from plants have been known to act as natural additives,” they write, “for example, antimicrobial agents, antioxidant, and so on. Their activities vary with source of plants, chemical composition, extraction methods, and so on. Due to the unique smell associated with the volatiles, this may limit the use of essential oil in some foods since it may alter the typical smell/flavor of foods.” Nevertheless, they conclude:
“Essential oils from different sources can be exploited as the natural additives in foods. Essential oils with other bioactivities or functions from new sources should be further searched. New technology for lowering the unique and undesirable smell of essential oil, which can limit their use in foods, such as encapsulation, and so on, must be implemented. As a consequence, essential oil can be widely used without any negative effect on sensory property of foods. The development of release system for essential oil from packaging or fuming system inside packaging should be conducted to maximize the activity of active compounds in essential oils. Therefore, it can serve as the convenient packaging, which effectively extends the shelf life of foods.”
In other words, essential oils probably aren’t going to be used by home food preparers to extend the shelf-life of their foods or to prevent food poisoning; but, they are likely to be more widely in the future by food manufacturers.