Oregano Oil's Germ-Fighting Power Enhanced by Cellulose Nanofiber Emulsions

Jim Crocker
1st July, 2024

Oregano Oil's Germ-Fighting Power Enhanced by Cellulose Nanofiber Emulsions

Essential oil from Oregano (Origanum vulgare, pictured), when encapsulated in a stable Pickering emulsion using cellulose nanofibers, demonstrated excellent antimicrobial activity against pathogenic bacteria and fungi.

Photo adapted from: Елена Кизилова / CC BY (Source)

Key Findings

  • Researchers at the University of Campinas (UNICAMP) used cellulose nanofibers (CNF) from cassava peel to stabilize oregano essential oil (OEO) emulsions
  • The CNF-stabilized emulsions showed excellent antimicrobial activity against bacteria and the fungus Alternaria alternata
  • Mixing OEO with sunflower oil improved the stability of the emulsions, making them more cost-effective and heat-resistant
Essential oils are known for their antimicrobial properties but often face challenges regarding their stability and availability. A recent study conducted by researchers at the University of Campinas (UNICAMP) explored a novel solution to these challenges by using Pickering-type emulsions to deliver oregano essential oil (OEO)[1]. The emulsions were stabilized using cellulose nanofibers (CNF) derived from cassava peel, a food industry waste, through enzymatic hydrolysis. This approach not only enhances the antimicrobial effect of OEO but also provides an environmentally sustainable method for emulsion stabilization. The study focused on how different properties of CNF affect the stability of emulsions. The researchers varied the composition of the dispersed phase by mixing different ratios of OEO and sunflower oil (SO) to target applications in biodegradable active coatings. Even at a very low concentration of 0.01% w/w, CNF was able to form kinetically stable emulsions with small droplet sizes using these oil mixtures. The stabilization mechanism was found to be not purely Pickering, as there was a reduction in interfacial tension. Previous studies have shown that cellulose-based nanomaterials can be effective stabilizers for Pickering emulsions. For instance, cellulose nanocrystals (CNCs) have been demonstrated to stabilize water-in-water emulsions[2]. Additionally, TEMPO-mediated oxidized cellulose nanofibers (TOCN) and chitin nanofibers have been used to form stable Pickering emulsions, with their effectiveness being influenced by concentration, surface wettability, and zeta-potential[3]. The current study expands on these findings by using CNF derived from a sustainable source and applying it to essential oil emulsions. The researchers at UNICAMP observed that the emulsions exhibited excellent antimicrobial activity against bacteria and the fungus Alternaria alternata. This suggests that these emulsions could be effectively used in active systems such as coatings and films. The study also found that using a mixture of oils improved the stability of emulsions, which is advantageous in terms of cost and stability to heat treatments, while maintaining the desired antimicrobial activity for the final application. The use of CNF as an emulsion stabilizer is particularly noteworthy due to its environmental sustainability. CNF was produced from cassava peel, a food industry waste, making it a cost-effective and eco-friendly option. This aligns with the increasing concern about developing biobased colloid particles for Pickering stabilization due to environmental and health-safety needs[3]. In another related study, cellulose nanofibers obtained from cassava peel through acid hydrolysis or TEMPO-mediated oxidation showed high negative zeta potential values and gel-like behavior in aqueous suspensions[4]. This indicates their potential use as reinforcement for nanocomposites or as thickening agents. The current study builds on this by demonstrating that CNF can also be used to stabilize essential oil emulsions effectively. Furthermore, the study's findings on the effect of different oil phases on emulsion stability align with earlier research that investigated how oil composition affects the stability of myofibrillar protein microgel particles stabilized Pickering emulsions[5]. Sunflower oil, with its low content of super-long-chain and saturated fatty acids, was found to enhance emulsion stability due to its lower viscosity. Similarly, the current study found that mixing OEO with SO improved emulsion stability, suggesting a broader applicability of these findings. In summary, the study conducted by UNICAMP researchers demonstrates a promising approach to stabilizing essential oil emulsions using cellulose nanofibers derived from food industry waste. This method not only enhances the antimicrobial properties of the emulsions but also offers an environmentally sustainable solution. By leveraging previous research on cellulose-based stabilizers and oil phase effects, this study provides valuable insights into the formulation of stable, cost-effective, and eco-friendly emulsions for various applications.

HerbsMedicineBiochem

References

Main Study

1) Antimicrobial potential of oregano essential oil vehiculated in Pickering cellulose nanofibers-stabilized emulsions.

Published 28th June, 2024

https://doi.org/10.1016/j.ijbiomac.2024.133457

Related Studies

2) Stabilization of Water-in-Water Emulsions by Nanorods.

https://doi.org/10.1021/acsmacrolett.5b00953

3) Comparison of cellulose and chitin nanofibers on Pickering emulsion stability-Investigation of size and surface wettability contribution.

https://doi.org/10.1016/j.ijbiomac.2023.123754

4) Rheological behavior of cellulose nanofibers from cassava peel obtained by combination of chemical and physical processes.

https://doi.org/10.1016/j.carbpol.2020.116744

5) Effect of oil phases on the stability of myofibrillar protein microgel particles stabilized Pickering emulsions: The leading role of viscosity.

https://doi.org/10.1016/j.foodchem.2023.135653


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