Changing essential oils increases the emulsification efficiency and antibacterial properties of clove oil

Clove essential oils are promising antibacterial substances. In a recent study, researchers at the University of Tokyo explore sustainable ways to create carbon quantum dots (CQDs) from the clove residue left after extracting essential oils. These CQDs were tested for their ability to form Pickering emulsions that enhance their antibacterial properties more stably compared to conventional emulsions using polysorbate 80.

Food-borne diseases pose major challenges to achieving the United Nations Sustainable Development Goal 3 of Health and Happiness. Such diseases usually occur due to bacterial contamination during food production, processing, transport and storage, and can even prove fatal. Therefore, it is essential to prevent microorganism contamination at all stages.

In this regard, the food industry is currently using chemicals such as benzotate and nitrates. Unfortunately, these preservatives are not considered safe and effective natural antibacterial agents. Scientists have recently proposed a promising alternative to volatiles, essential oils produced through secondary metabolism in plants.

In their research, a team of researchers led by Jun Wong Kang, an assistant professor in the Faculty of Food Science and Biotechnology at Dongguk University, came up with a new clove essential oil-based Pickering emulsion formulation with enhanced antibacterial properties. Their findings were published in the Journal of Chemical Engineering on January 1, 2025.

According to Dr. Kang, “Clover essential oils are known to exhibit excellent antibacterial properties. However, their applications are limited by their low water solubility. To overcome this, we decided to explore oil-based Pickering emulsions.”

In this study, the researchers developed a sustainable Pickering emulsion using promising carbon quantum dots (CQDs) with promising solid particles for food applications derived from residues of clove essential oils. Specifically, we synthesized four types of CQDs using ultrapure distilled water and ethanol, and found that CQDs with 40% ethanol showed the best emulsifying effect.

CQD increases the surface roughness of the emulsion, promotes bacterial adhesion, and has a stronger antibacterial activity than conventional emulsions. The current approach not only increases the antibacterial efficiency of emulsions, but also provides an environmentally friendly alternative to traditional chemical surfactants such as polysorbate 80. Upcycling essential oil extraction byproducts contributes to sustainable material development and waste disposal.

This work is expected to find several interesting applications in many areas. The developed Pickering emulsion can be used for food storage and packaging to enhance shelf life by naturally preventing bacterial contamination. Furthermore, essential oils are already widely used in skin care products, so the proposed emulsions can be used in natural cosmetics and topical antibiotics.

Furthermore, the antibacterial properties of emulsions suggest potential applications in wound dressings, preservative formulations, or drug delivery systems. The formulations can also be applied to biopesticides or plant protection products that require stable emulsions with antibacterial properties.

“In summary, novelties in clove essential oil-based technologies include reductions in chemical surfactants, health benefits, sustainability, waste reduction, promotion of circular economy, advanced antibacterial functions, medical applications, and the potential for widespread industrial adoption,” concludes Dr. Kang.

Researchers hope that the study will soon lead to new regulatory standards that support environmentally friendly, bio-based, and non-toxic emulsifiers than synthetics, and shape the landscape of multiple industries.