Porous Coatings to Control Release Rates of Essential Oils to Generate an Atmosphere with Botanical Actives

Abstract

Essential oils have been used in diverse areas such as packaging, agriculture and cosmetics, for their antimicrobial and pesticide activity. The organic volatile compounds of the essential oils are involved in its activity. Controlling their release helps to prolong their functionality. In this study, a functionalized calcium carbonate porous coating was employed to control the release of thyme and rosemary oil in a confined space. The release rate was evaluated at 7 °C and 23 °C, gravimetrically. It was shown that the capillary effect of the porous coating slowed down the release of the volatiles into the headspace compared to the bulk essential oil. A linear drive force model was used to fit the obtained data from both essential oils. The model showed that rosemary reached the asymptotic mass loss equilibrium faster than thyme. This result can be explained by the diverse composition and concentration of monoterpenoids between the two essential oils. Temperature and degree of loading also played important roles in the desorption of the essential oils. It was observed that at high degrees of loading and temperatures the desorption of essential oils was higher. The above-described technology could be used for applications related to food preservation, pest control among others.

Essential Oils of Mentha arvensis and Cinnamomum cassia Exhibit Distinct Antibacterial Activity at Different Temperatures In Vitro and on Chicken Skin

“…This phenomenon, along with the antibacterial mechanism of menthol, requires a deeper investigation. Apart from the MEO effects on the viability of S. typhimurium cells, our results are consistent with the general principle that more EO evaporates at higher temperatures; thus, the killing of bacteria is faster at higher temperatures [55]. However, the actions of EOs are not always predictable, even based on the boiling temperatures of the components; the mechanisms of EOs are more complicated and still require elucidation [16].…”

Encapsulation of Eucalyptus largiflorens Essential Oil by Mesoporous Silicates for Effective Control of the Cowpea Weevil, Callosobruchus maculatus (Fabricius) (Coleoptera: Chrysomelidae)

“…For example, Milićević et al [ 67 ] indicated that zeolite adsorbs the droplets of clove bud essential oil due to its porosity; the insecticidal, antifungal, and antibacterial effects of essential oils were augmented by loading in this porous material. In a study by Hettmann et al [ 68 ], a functionalized calcium carbonate porous coating was used for controlled release of rosemary and thyme essential oil. The authors found that thyme essential oil required almost double the time required by rosemary essential oil to reach the saturation point, which can be explained by diverse chemical composition and concentration of monoterpenes between the two essential oils.…”

“…Essential oil evaporates from the pores of porous materials and distributes to the air. The study by Hettmann et al [ 68 ] mainly focused on physical influences, including degrees of loading and temperature, on release of essential oils from porous materials.…”