Changes in characteristics of nanoemulsion of cinnamon oil and their relationships with instability mechanisms during storage

Abstract

Development of nano‐structured food delivery systems containing essential oils are finding growing interest due to their unique physicochemical and potential functional properties such as high stability, optical transparency, and improved bioactivity. Cinnamon oil of bark of Cinnamomum burmannii was formulated into nanoemulsion systems and their characteristics during storage were evaluated to obtain their relationships with possible destabilization mechanisms. Nanoemulsion was prepared using a phase inversion technique incorporating cinnamon oil (5% and 10%) and non‐ionic emulsifier (75% of the oil). The emulsions were kept at 20, 30, 40°C and their physical characteristics were analyzed over time during 8 weeks storage. Average droplet sizes of 192.6 and 184.3 nm were produced at the beginning of storage and they tended to increase during storage. Droplet sizes and polydispersity index exhibited the same increase trends, while the absolute value of zeta potential and viscosity showed decrease trends in general. Creaming appeared to dominate the destabilization of nanoemulsion accompanied by Ostwald ripening and followed by oil sedimentation. Practical applications Consumers become more aware of the uses of natural ingredients in food formulation in‐line with the increase trends in back‐to‐nature lifestyle. Cinnamon oil has been used for food flavoring and preservation but its incorporation into aqueous‐based formulation is still difficult due to its hydrophobicity. Development of nanoemulsion is a prospective approach to the dispersity problem. This study provides valuable information in formulating nanoemulsion suitable for the food delivery system. Identification of changes in nanoemulsion characteristics during storage gives the feature of coarsening behavior useful in designing approaches to control their instability.

Production of clove oil nanoemulsion with rapid and enhanced antimicrobial activity against gram‐positive and gram‐negative bacteria

“…Still a visual phase separation after 60 days indicating a complete loss of colloidal stability. Similar results were found in another work that studied the instability mechanisms of cinnamon oil NE during storage (Yuliani & Syakir, ). The NEs were prepared using only essential oil and ionic emulsifier and creaming appeared to dominate the destabilization of NE accompanied by Ostwald ripening and followed by oil sedimentation.…”

“…Generally, the authors use only surfactants to stabilize essential oils NE and minimize droplet destabilization (Ghosh et al, ; Gundewadi, Jyoti, Gaur, & Singh, ; Sharma et al, ; Sugumar et al, ; Yuliani & Syakir, ). However, the use of an ultrahydrophobe like crodamol, frequently used for miniemulsion polymerization reactions (Cardoso, Araújo, & Sayer, ; Katharina Landfester, ; Machado, Cardoso, Feuser, Sayer, & Araújo, ), improves the dispersed phase osmotic pressure and counteracts the Laplace pressure responsible for diffusional degradation, consequently acting as a costabilizer (Asua, ; K Landfester, ).…”

“…The results presented in Figure show that NE with just essential oil and surfactant in formulation undergoes diffusional degradation known as Ostwald ripening, probably due to the water‐soluble part of the CO main component (eugenol) providing the access to Ostwald ripening in oil‐in‐water NE (McClements, ; Nazarzadeh, Anthonypillai, & Sajjadi, ; Yuliani & Syakir, ). In the Ostwald ripening, the smaller droplets present a higher Laplace pressure resulting in an increased water‐solubility of the compounds that present water solubility to some extent, like eugenol.…”

“…The NEs were stored under refrigeration during 30 and 60 days and results of Dp and PdI are presented in Figure 1. (Yuliani & Syakir, 2018). The NEs were prepared using only essential oil and ionic emulsifier and creaming appeared to dominate the destabilization of NE accompanied by Ostwald ripening and followed by oil sedimentation.…”

Development of nano-emulsions based onAyapana triplinervisfor the control ofAedes aegyptilarvae

“…The narrowest emulsions were produced in HLB 16, and their particle size ranged from 88.830 nm to 99.463 nm for the Morphotype A essential oil, and between 99.637 nm to 99.420 nm for the Morphotype B essential oil between days 0 and 21, as shown in the particle size distribution in Fig 2. Emulsions with particle diameters between 20 and 200 nm are called nano-emulsions and possess stability against cremation, flocculation, and sedimentation, but are susceptible to Ostwald ripening over time [43–44].…”