March 07, 2025 -- Clove essential oil is a promising antibacterial substance. In a new study, researchers from Dongguk University explore a sustainable way to create carbon quantum dots (CQDs) from clove residue left after extracting essential oil. These CQDs were tested for their ability to form Pickering emulsions, which are more stable and have enhanced antibacterial properties compared to traditional emulsions using Polysorbate 80. Thus, the proposed emulsions are promising for food and cosmetic applications.

Foodborne diseases pose a significant challenge to achieving the United Nations Sustainable Development Goal 3 of Good Health and Well-Being. Such ailments typically occur due to bacterial contamination during food production, processing, transportation, and storage and can even prove fatal. Therefore, it is imperative to prevent contamination due to microbes at all stages. 

In this regard, the food industry currently utilizes chemicals such as benzoate and nitrate. Unfortunately, these preservatives are not deemed as safe and effective natural antibacterial agents. Scientists have recently proposed essential oils, volatile substances produced through the secondary metabolism of plants, as promising alternatives. 

In a breakthrough, a team of researchers led by Jun-Won Kang, an Assistant Professor in the Department of Food Science and Biotechnology at Dongguk University, has come up with a novel clove essential oil-based Pickering emulsion formulation with enhanced antibacterial properties. Their findings were made available online on 3 December 2024 and published in Volume 503 of the Chemical Engineering Journal on 1 January 2025. 

According to Dr. Kang, “Clove essential oil is known to exhibit excellent antibacterial properties. However, its application has been limited by 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 carbon quantum dots (CQDs), promising solid particles for food applications, derived from clove essential oil residue. Specifically, they synthesized four kinds of CQDs using ultrapure distilled water and ethanol, finding that CQDs with 40% ethanol demonstrated the highest emulsifying efficacy. 

CQDs increase the surface roughness of the emulsion, enhancing bacterial adhesion and leading to stronger antibacterial activity compared to conventional emulsions. The present approach not only enhances the antibacterial efficiency of emulsions but also offers a green and eco-friendly alternative to traditional chemical surfactants such as Polysorbate 80. It showcases the upcycling of essential oil extraction byproducts into valuable emulsifying agent nanomaterials, contributing to sustainable material development and waste valorization.

This work is expected to find several interesting applications across numerous fields. The developed Pickering emulsion can be used in food preservation and packaging to enhance shelf life by naturally preventing bacterial contamination. Additionally, since essential oils are already widely used in skincare products, the proposed emulsion could be used in natural cosmetics and topical antimicrobial formulations.

Moreover, the antimicrobial properties of emulsion suggest potential applications in wound dressings, antiseptic formulations, or drug delivery systems. The formulation could also be applied to biopesticides or plant protection products that require stable emulsions with antimicrobial action.

“To summarize, the novelties of our clove essential oil-based technology include reduction of chemical surfactants, health benefits, sustainability, waste reduction, circular economy promotion, advanced antimicrobial features, medical applications, and potential for widespread industrial adoption,” concludes Dr. Kang.

Here’s hoping that this research soon leads to new regulatory standards favouring eco-friendly, bio-based, and non-toxic emulsifiers over synthetic ones, shaping the landscape of multiple industries!