Plant essential oil nanoemulsions can be formulated using low- and high-energy methods. These nanometric delivery systems can be incorporated into food and beverage systems to increase the antimicrobial activity, reducing the amount of the antimicrobial compound required and, therefore, minimizing the impact on the quality of the final product. Nanoemulsion-based delivery systems, fabricated by ultrasonication or high-pressure homogenization with food grade ingredients, are able to protect the essential oil components. Nanoemulsion requires a lower concentration of oil and surfactant compared with conventional emulsion formulation. The emulsion penetrates into the membrane of the bacterial cell wall and activates passive transport through the cell membrane, thus increasing antimicrobial activity. © 2016 by Elsevier, Inc.. All rights reserved.

Amitava Mukherjee

Centre for Nanobiotechnology

Vellore Campus

Chandra Sekaran N

Sugumar S

Ghosh V

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Essential Oil-Based Nanoemulsion Formation by Low- and High-Energy Methods and Their Application in Food Preservation against Food Spoilage Microorganisms

Essential Oils in Food Preservation, Flavor and Safety

The plant derived essential oil nanoemulsion was prepared using a mixture of components containing eucalyptus oil as organic phase, water as continuous phase, and non ionic surfactant, Tween 80, as emulsifier at a particular proportion of 1:1 v/v%. The ultrasonication was applied for varied processing time from 0 to 30 min to study the effect of time on the formation of nanoemulsion and physical stability of formulation by this method. The transparency and stability of emulsion was enhanced when the sonication time was increased compared to hand blender emulsion. The most stable nanoemulsion was obtained in 30 min sonication having the mean droplet diameter of 3.8 nm. The antibacterial studies of nanoemulsion against Staphylococcus aureus by time kill analysis showed complete loss of viability within 15 min of interaction. Observations from scanning electron microscopy of treated bacterial cells confirmed the membrane damage compared to control bacteria. Furthermore, the wound healing potential and skin irritation activity of the formulated nanoemulsion in Wistar rats, suggested non-irritant and higher wound contraction rate with respect to control and neomycin treated rats. These results proposed that the formulated system could be favourable for topical application in pharmaceutical industries. © 2013 Elsevier B.V. All rights reserved.

Fulltext

Ultrasonics Sonochemistry

Ultrasonic emulsification of eucalyptus oil nanoemulsion: Antibacterial activity against Staphylococcus aureus and wound healing activity in Wistar rats

Oil-in-water nanoemulsion was formulated using sesame oil, non-ionic surfactant (Tween20/Tween80) and water by ultrasound cavitation method. Development of nanoemulsion was optimized for process parameters such as surfactant type, surfactant concentration and emulsification time to obtain lower droplet diameter with greater stability. Increase in surfactant concentration and emulsifi{ligature}cation time resulted in nanoemulsion with minimized droplet diameter. Tween80 was more effective in reducing droplet size when compared to that of Tween20. Selected formulation with optimized process parameter (with oil-surfactant mixing ratio of 1:3 v/v and Tween80 as surfactant) was used for delivery of eugenol. Eugenol-loaded nanoemulsion was formulated with droplet diameter of 13. nm and was stable for more than 1 month. Sesame oil blended eugenol-loaded nanoemulsion demonstrated lower droplet size and higher stability than only-eugenol (without sesame oil) nanoemulsion. Eugenol-loaded nanoemulsion S3E3 exhibited antibacterial activity against Staphylococcus aureus. Inactivation kinetics of S. aureus showed time and concentration killing of bacteria upon treatment with S3E3 nanoemulsion. Fluorescence microscopy results demonstrated that S3E3 nanoemulsion treatment resulted in alteration of membrane permeability. In situ assessment of S3E3 in orange juice exhibited a significant reduction in the native bacteria population. © 2013 Elsevier B.V.

Colloids and Surfaces B: Biointerfaces

Eugenol-loaded antimicrobial nanoemulsion preserves fruit juice against, microbial spoilage

The current study deals with the formulation and characterization of bio-based oil in water nanoemulsion and its potential antibacterial activity. A typical v/v% of eucalyptus oil (16.66%), Tween 80 (16.66%), and water (68.68%) was prepared by ultrasonication method. The mean droplet size was 17.1nm as confirmed by dynamic light scattering. Different concentrations of the formulation ranging from undiluted to 10-, 100-, and 1000-fold dilutions were used to check the antibacterial activity in three different microorganisms, namely, Bacillus cereus, Staphylococcus aureus (Gram-positive), and Escherichia coli (Gram-negative). All three species showed a 100% bactericidal at the 10-fold dilution of the nanoemulsion formulation in the following order: B. cereus at 0th min, S. aureus at 15min and E. coli at 1h, respectively. A 10-fold dilution of the nanoemulsion showed that, the cytoplasmic content leakage from the bacterial species was high for S. aureus when compared to B. cereus and E. coli as determined by UV-Vis spectroscopic method. Fluorescence microscopic technique further confirmed this study. © 2013.

Journal of Basic Microbiology

Bio-based nanoemulsion formulation, characterization and antibacterial activity against food-borne pathogens

Cinnamon oil (extracted from Cinnamomum zeylanicum) nanoemulsion was formulated using Tween 80 and water by ultrasonic emulsification. Process of nanoemulsion formulation was optimized for parameters such as surfactant concentration, oil-surfactant mixing ratio and emulsification time. Surfactant concentration was found to be inversely related to droplet size and directly related to stability. Increase in emulsification time resulted in decrease in droplet diameter. Stable cinnamon oil formulation (CF3) having droplet diameter of 65 nm was formulated after sonication for 30 min. Formulated nanoemulsion was evaluated for bactericidal efficacy against Bacillus cereus. Time and concentration dependent killing of B. cereus cells was observed upon treatment with nanoemulsion. Even at a higher dilution of CF3, significant reduction in bacterial population was observed. Alteration in membrane permeability of interacted samples was suggested by quantifying the release of UV absorbing materials. Bacterial staining with acridine orange/ethidium bromide supported kinetics of killing data and also substantiated the above findings of alteration in membrane permeability. FTIR illustrated disappearance of peak corresponding phosphate vibration at 1078 cm-1 and 536 cm-1, and peak associated with vibration of acyl chains of lipid at 2852 cm-1 was shifted to 2854 cm-1 which suggested deformation of membrane phospholipids in nanoemulsion treated cells. SEM observations demonstrated membrane distortion leading to cell lysis. These results propose the potential use of cinnamon oil nanoemulsion for preservation of minimally processed food. Copyright © 2013 American Scientific Publishers All rights reserved.

Journal of Nanoscience and Nanotechnology

Cinnamon Oil Nanoemulsion Formulation by Ultrasonic Emulsification: Investigation of Its Bactericidal Activity

Basil oil (Ocimum basilicum) nanoemulsion was formulated using non-ionic surfactant Tween80 and water by ultrasonic emulsification method. Process of nanoemulsion development was optimized for parameters such as surfactant concentration and emulsification time to achieve minimum droplet diameter with high physical stability. Surfactant concentration was found to have a negative correlation with droplet diameter, whereas emulsification time had a positive correlation with droplet diameter and also with intrinsic stability of the emulsion. Stable basil oil nanoemulsion with droplet diameter 29.3 nm was formulated by ultrasonic emulsification for 15 min. Formulated nanoemulsion was evaluated for antibacterial activity against Escherichia coli by kinetics of killing experiment. Fluorescence microscopy and FT-IR results showed that nanoemulsion treatment resulted alteration in permeability and surface features of bacterial cell membrane. © 2012 Elsevier B.V. All rights reserved.

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