Meat and meat products are highly prone to microbial contamination since they are intrinsically prone to spoiling, rich in essential nutrients and perishable.
As demand grows for minimally processed, ready-to-eat meat products that are also all-natural and clean-label, plant-derived essential oils (EOs) offer a compelling all-natural (and low sodium) alternative to synthetic food additives as effective antimicrobial agents, according to research compiled by Dinesh D. Jayasena and Cheorun Jo at the Department of Animal Science and Biotechnology, Chungnam National University, Daejeon, Korea.
EOs are the aromatic, volatile oily extracts obtained from aromatic and medicinal plant materials, including flowers, buds, roots, bark, and leaves. Phenolic compounds, such as carvacrol (active in oregano), eugenol (clove), and thymol (thyme), are mainly responsible for the antimicrobial activity of EOs.
For the study, titled 'Essential oils as potential antimicrobial agents in meat and meat products: A review,' Jayasena and Jo cited numerous studies examining the effects of EOs obtained from such plants as oregano, rosemary, thyme, sage, basil, turmeric, coriander, ginger, garlic, nutmeg, clove, mace, savory, and fennel, when used alone or in combination with other EOs and/or preservation methods to improve the sensory qualities and extend the shelf life of meat and meat products.
“In brief, EOs can degrade the cell wall, disturb the phospholipid bilayer of the cytoplasmic membrane, and damage the membrane proteins leading to increased permeability of the cell membrane and loss of cellular constituents,” the authors wrote.
In particular, EOs from “oregano, rosemary, thyme, clove, balm, ginger, basilica, coriander, marjoram, and basil have shown a greater potential to be used as an antimicrobial agent,” they noted.
Herb EOs in particular show promise
Among the findings cited, incorporation of oregano EO in meat and meat products has been found to be effective against spoilage microflora (Salmonella Enteritidis) on meat products such as minced mutton, salted fish roe and beef fillets.
Thyme EOs were found to inhibit E. Coli in minced beef, while thyme and balm EOs reduced the natural microflora counts present in chicken breast meat. The addition of rosemary or thyme EOs to fine paste meat products, such as bologna-type sausages, has been effective against aerobic bacteria and LAB.
Minced mutton treated with clove EOs also exhibited restricted growth of L. monocytogenes.
Ginger- and basil EO-treated beef patties showed improved stability. Clove, cinnamon, pimento, and rosemary EOs effectively inhibited the growth of meat spoilage bacteria. Further, cumin, garlic, oregano, and black pepper EOs considerably inhibited the growth of meat spoilage organisms.
But, there are limitations
Despite the plethora of promising antimicrobial activities for many EOs, the authors found that use of EOs is sometimes limited because of their often intense aromas. Additionally, the interaction of certain EOs with food ingredients could decrease their effectiveness—indeed, the presence of fat, carbohydrates, proteins and salts in meat and meat product food systems could result in reduced activity of EOs.
“For instance, mint and cilantro EOs were not effective against L. monocytogenes in products containing high levels of fat, such as pâté and a coating for ham containing canola oil,” the authors found.
It also could be hard to maintain quality consistency, as individual EO composition can vary based on factors such as time of harvesting, variety and the part of the plant used.
But advanced technologies—such as encapsulation of EOs in polymers of edible coatings or combining them in lower concentrations with other preservative technologies—could improve both microbial stability and sensory quality.
“Essential oils as potential antimicrobial agents in meat and meat products: A review, doi: 10.1016/j.tifs.2013.09.002
Authors: Jayasena, D.D., Jo, C.