Essential Oils and Food Safety
Happy New Year! Peer-reviewed 2016 studies are just beginning to appear. But already we see a trend developing.
You will surely recall the recent E. coli outbreak from chicken salad at Costco warehouses in seven states. By November 23, 2015, 19 people were infected with the sometimes deadly E. coli 0157:H7. Apparently the culprit was not the chicken but a celery and onion mix.
- Our first study is from food safety experts at the University of Santiago de Chile, Santiago, Chile. They report that “An important issue in food technology is that antimicrobial compounds can be used for various applications, such as the development of antimicrobial active packaging materials. Yet most antimicrobial compounds are volatile and require protection.”1
Not being food scientists, we will just tell you that the essential oil component (unfortunately not mentioned in the abstract) was kept in place with 2-nonanone (2-nn) with β-cyclodextrin (β-CD). The essential oil antimicrobial action was thus not lost through volatility, and the study concludes: “Antimicrobial tests for mycelial growth reduction under atmospheric conditions proved the fungistatic behaviour of the inclusion complexes against Botrytis cinerea.”2 (This fungus loves wine grapes and is called “botrytis bunch rot.” Horticulturalists call it grey mold.)
- Oregano essential oil stars in a bioactive fish gelatin/chitosan nanoparticle composite film that has antimicrobial particles. The Origanum vulgare L. essential oil actually made the film matrix less resistant and more flexible. The 2016 study states: “The FC/CSNPs [fish gelatin/chitosan nanoparticles] bioactive films exhibited distinctive antimicrobial activity against four test food pathogens, namely Staphylococcus aureus, Listeria monocytogenes, Salmonella enteritidis, and Escherichia coli.”3
- Food science terminology is getting more and more technical! Our third study takes advantage of the antimicrobial power of cinnamon essential oil (CEO). It is added to a beta-cyclodextrin inclusion complex into polylactic acid nanofibers via electrospinning technique. The abstract tells us that the “mild electrospinning process was more favorable for maintaining greater CEO [cinnamon essential oil] in the obtained film.”4 In view of the terrible breach of the last-resort antibiotic in China (November 2015), the conclusion of this study should be taken to heart by those pork-loving folks. “The PLA/CEO/β-CD nanofilm can effectively prolong the shelf life of pork, suggesting it has potential application in active food packaging.”5 [Emphasis added]
- Our final 2016 study investigates how best to retain the health benefits of thymol and carvacrol in cooking. Again, we have Chilean food scientists but this time from the Universidade Austral de Chile in Valdivia, Chile.
They report that “Oregano and thyme possess beneficial properties for human health, mainly attributable to monoterpenes such as thymol and carvacrol.”6 The food scientists’ objective was to assess the impact of boiling and baking in starchy foods on both the essential oil and ground leaves of these two important food spices.
Their results indicate that bio-accessibility is weakly dependent on cooking and delivery modes (either essential oil or leaves). “Boil cooking presented 20% more retention than baking for both compounds. When essential oil was added to the food matrix, thymol was retained almost 25% more when compared with ground leaves addition. Conversely, carvacrol was retained 39% more when ground leaves were added.”7
When researchers are telling us that the breach of the last-resort antibiotic, colistin, means a return to the pre-antibiotic era—we know we are in trouble. Essential oils are complex entities that have been shown time and time again to be too complex for many bacterial strains to conquer. Now these precious oils will be used in food packaging to protect us from harm. Hats off to essential oils!
- Abarca RL, et al. Characterization of beta-cyclodextrin inclusion complexes containing an essential oil component. Food Chem. 2016 Apr 1;196:968-75. [Epub ahead of print]
- Hosseini SF, et al. Development of bioactive fish gelatin/chitosan nanoparticles composite films with antimicrobial properties. Food Chem. 2016 Mar 1;194:1266-74. [Epub ahead of print]
- Wen P, et al. Fabrication of electrospun polylactic acid nanofilm incorporating cinnamon essential oil/β-cyclodextrin inclusion complex for antimicrobial packaging. Food Chem. 2016 Apr 1;196:966-1004. [Epub ahead of print]
- Aravena G, et al. The impact on cooking and delivery modes of thymol and carvacrol on retention and bioaccessibility in starchy foods. Food Chem. 2016 Apr 1;196:848-52. [Epub ahead of print]