Researchers of Valencia’s Polytechnic University (UPV) and of the Agrochemistry and Food Technology Institute (IATA), a centre of the Spanish National Research Council (CSIC), have studied the effectiveness of new antimicrobial systems based on the use of essential oils extracted from plants such as thyme or cinnamon to improve the preservation of foods.
Consumers are becoming more and more demanding with the food they eat. On one hand, they want it to have a long shelf life that facilitates its home storage for a lengthy period of time. But they also prefer that preservation technologies applied to this end do not modify the nutritional and sensorial properties of the foods, which is common with thermal processes, and also that they do not add additives. Taking on these limitations therefore requires the development of new microbial stabilisation techniques, which include new antimicrobial agents.
The novelty of this work consists on the chemical immobilisation of the essential oil on platforms that are authorised for being used with foods, in a way that they keep the traditional antimicrobial activity of essential oils without reaching the food.
To this date, they have been applied to treat the microorganisms that alter wine, and managed to stunt their growth. Based on the results of this work, there is currently new research being carried out which suggests that the antimicrobial systems developed can be used to microbiologically stabilise wines, thus decreasing the amount of additives such as sulphites.
The design of new antimicrobial systems comes from a prior collaboration between the groups of researchers from the UPV’s Food Technology Department and members of the Molecular Recognition and Technological Development Institute (IDM-UPV), a development which is protected with a patent.
No smell or taste
“Currently, the use of essential oils entails a strong smell and taste, low stability and interaction with the food matrix that decreases its antimicrobial effect. Our system prevents these drawbacks, so that the consumer perceives the product as if it had not been processed – while the removal of altering microorganisms is complete,” highlights María Ruiz, researcher at the UPV’s Food Technology Department.
The systems used in this study by the UPV and IATA researchers are based on the covalent immobilisation of components of the essential oils on silica and cellulose microparticles as well as cellulose membranes . This way, the antimicrobials can’t reach the food, and its smell can therefore not be perceived by the consumer. “Furthermore, if the immobilisation conditions are properly controlled, you can get the essential oil components to preserve or even increase their antimicrobial properties,” explains María Ruiz.
The antimicrobial systems developed by UPV and IATA researchers could be used as new food additives to microbiologically stabilise other products, in order to replace or reduce the addition of synthetic chemical preservatives. They could also be used for the design of a new cold pasteurisation process for liquid foods.
García-Ríos, E., Ruiz-Rico, M., Guillamón, J. M., Pérez-Esteve, É., & Barat, J. M. (2018). Improved antimicrobial activity of immobilised essential oil components against representative spoilage wine microorganisms. Food Control, 94, 177-186 https://doi.org/10.1016/j.foodcont.2018.07.005