Cinnamon Oil Nanoemulsion Research Articles

Nanoemulsion of cinnamon oil to combat colistin-resistant Klebsiella pneumoniae and cancer cells

This study aimed to investigate the potential of cinnamon oil nanoemulsion (CONE) as an antibacterial agent against clinical strains of colistin-resistant Klebsiella pneumoniae and its anticancer activity. The prepared and characterized CONE was found to have a spherical shape with an average size of 70.6 ± 28.3 nm under TEM and a PDI value of 0.076 and zeta potential value of 6.9 mV using DLS analysis. The antibacterial activity of CONE against Klebsiella pneumoniae strains was investigated, and it was found to have higher inhibitory activity (18.3 ± 1.2–30.3 ± 0.8 mm) against the tested bacteria compared to bulk cinnamon oil (14.6 ± 0.88–20.6 ± 1.2) with MIC values ranging from 0.077 to 0.31 % v/v which equivalent to 0.2–0.82 ng/ml of CONE. CONE inhibited the growth of bacteria in a dose and time-dependent manner based on the time-kill assay in which Klebsiella pneumoniae B-9 was used as a model among the bacterial strains under investigation. The study also investigated the expression of the mcr-1 gene in the Klebsiella pneumoniae strains and found that all strains were positive for the gene expression and subsequently its presence. The level of mcr-1 gene expression among the B-2, B-4, B-9, and B-11 control strains and that treated with colistin was similar, but it was different in both B-5 and B-2. However, all strains exhibited a significant downregulation in gene expression (ranging from 3.97 to 8.7-fold) after their treatment with CONE. Additionally, the CONE-treated bacterial cells appeared with a great deformation compared with control cells under TEM. Finally, CONE exhibited selective toxicity against different cancer cell lines depending on comparison with the normal cell lines.

Enhancing functional properties of active chitosan film incorporated with cinnamon oil nanoemulsion using argon dielectric barrier discharge cold plasma treatment

The effects of cold plasma treatment (CPT) and cinnamon oil nanoemulsion (CN) on the functional properties of chitosan film were investigated. CN with particle size of 72.20 nm was prepared by ultrasonication method before incorporating into chitosan. Chitosan film (CS) and CS incorporated with CN (CS–CN) were monitored for surface roughness, tensile strength (TS), elongation at break (EAB), optical properties, water vapor permeability (WVP), oxygen transmission rate (OTR), contact angle, and antimicrobial activity against E. coli and S. aureus. CS-CN had lower OTR and contact angle than CS due to the molecular structure reorientation of the CS polymer matrix caused by CN. CS-CN had better antimicrobial activity than CS due to the bioactive compounds from the CN. Depending on the CPT time, CPT could improve roughness, TS, wettability and antimicrobial activity of both CS and CS-CN through the formation of the oxygen-containing groups such as –OH, and –CO and the occurrence of the etching effect of high energy plasma on the film surface, as evident by the analyses of fourier transform infrared spectroscopy, atomic force microscopy, and scanning electron microscopy. Moreover, crosslinking induced by CPT could improve oxygen barriers of films. The increase of antimicrobial activity of CS-CN was potentially because CPT generated reactive species damaged the bacterial cell, facilitated the diffusion of CN through the film matrix, and enhanced the release of CN from the film surface. The CPT-treated CS-CN has potential to be used as active film for food.

Green active coating from chitosan incorporated with spontaneous cinnamon oil nanoemulsion: Effects on dried shrimp quality and shelf life

Green active film from chitosan (C) incorporated with spontaneous emulsified cinnamon oil nanoemulsion (CONE; droplet size of 79.27 nm and polydispersity index of 0.27) was developed. The obtained chitosan film containing CONE (C + CONE) had tensile elongation and light protective effect higher than C film due to the incorporation of bioactive compounds from cinnamon oil as proven by Fourier Transform Infrared Spectroscopy. The effect of C + CONE as active edible coating on the physical, chemical, and microbiological properties of dried shrimp was then investigated. The quality of samples coated with C + CONE (DS + C + CONE) was compared to those coated with C (DS + C) and without coating (DS). In this study, C + CONE could enhance astaxanthin content and reduce lipid oxidation in dried shrimp. During 6 weeks of storage, C + CONE was found to be an effective antimicrobial coating that significantly inhibited growth of bacteria, delayed lipid oxidation and retarded the production of volatile amines in dried shrimp. DS + C + CONE had lower malonaldehyde equivalents (0.52 mg/kg oil), trimethylamine (11.74 mg/100 g), total volatile base nitrogen (84.33 mg/100 g) and total viable count (4.80 Log CFU/g), but had higher astaxanthin content (12.53 ± 0.12 μg/g) than DS and DS + C. The results suggested that the developed C + CONE coating has potential to be used as active coating for preserving food quality.

Inhibitory effect of some probiotic strains and essential oils on the growth of some foodborne pathogens.

Bacillus cereus and Yersinia enterocolitica are implicated in foodborne diseases that have major effects on human health; therefore, it is considered universal public health disorders. Essential oils and essential oils nano emulsions have a sufficient antibacterial performance against a variety of bacteria, especially multi-drug resistant bacteria. Probiotics showed several health benefits via moderating the GIT microbiota and their metabolites. The study was designed to evaluate the biocontrol ability of cinnamon essential oil (CEO) nano emulsion and probiotics as natural antibacterial additives and reveal their bactericidal mechanism. 250 random samples (50 raw milk, 50 rice pudding, 50 kariesh cheese, 50 yogurt, and 50 ice cream) were purchased separately from different areas in Mansoura city, Egypt, and exposed to bacteriological analysis. Bacillus cereus was found with the highest mean value of 66 × 107 ± 1.3 × 108 CFU/g in raw milk and the lowest mean value of 28 × 107 ± 2.6 × 107 CFU/g in kariesh cheese while Y. enterocolitica was found in 64% of the total inspected samples with the highest incidence (84%) in yogurt. The toxinogenic potential of the tested pathogens has been evaluated by multiplex PCR pointing nhe A and ces genes for B. cereus isolates while targeting in Y. enterocolitica 16s rRNA, and YST gene. Different concentrations (0.17%, 0.25%, 0.5%, 0.8%, 1%, 1.5%, and 2%) of cinnamon oil nano emulsion were employed in this study. CEO nano emulsion had the highest reduction rate at a concentration of 1.5% in the case of B. cereus and 2% in the case of Y. enterocolitica. Among different types of probiotics, the best one which showed inhibitory potential against B. cereus and Y. enterocolitica was L. plantarum. Lactobacillus plantarum and CEO nano emulsion at a concentration of 2% have the highest reduction rate against Y. enterocolitica, while L. plantarum and CEO nano emulsion at a concentration of 1.5% has the best antibacterial effect against B. cereus. In conclusion, more attention is required for both safety and quality in dairy products through the application of natural additives such as essential oils and probiotics.

Development and evaluation of clove and cinnamon oil-based nanoemulsions against adult fleas (Xenopsyllacheopis)

Adult fleas is one of the important vector borne insects which transmitting many diseases to mammals (cats, dogs, rodents, and humans) and birds worldwide. Because of the impact of climatic changes, the distribution of transmitted vector-borne pathogens may change, as well as the host ranges and the spread of diseases. Rat flea, Xenopsylla cheopis, can transmit Plague, a dangerous infectious disease caused by the bacterium Yersinia pestis. As the widespread use of synthetic insecticides to control fleas for a long time led to the development of insect resistance, and adverse health effects on humans, animals, and the ecosystem. This is the first work for formulating and evaluating clove and cinnamon oil nanoemulsions and studying their effect on adult flea. Clove and cinnamon nanoformulations were prepared and subjected to physicochemical and stability studies. Results showed that the small droplet size of nanoformulations was 158.4 nm and 282.5 nm of clove and cinnamon oils at a ratio of 1:2 of oil: tween 80 with 15 min as the sonication time. Cinnamon nanoemulsions have high insecticidal activity against flea compared to clove nanoemulsions. The LC50 account for 14.50 μg/ml and 26.42 μg/ml with a 39.90% increase in cinnamon nanoemulsion activity compared to clove nanoemulsion, respectively. Cinnamon nanoformulation is solvent-free and did not have any toxic effects on experimental animals and EC50 more than 100 mg/l (EC50 > 100 mg/l) on Vibrio fischeri bacteria. Therefore, it considers an eco-friendly green nano-insecticide for controlling Xenopsylla cheopis flea.

Cinnamon oil nanoemulsion as a novel nanocarrier for bleomycin amplifies its apoptotic effect on SKOV-3 ovarian cancer cells

Loading the chemotherapeutic agents in nanoemulsions system has recently gained attraction in medicine due to their ability to improve the drug’s efficacy and reduce its adverse effects. In this context, here, we loaded bleomycin (BLM) in nanoemulsion (NE) consisting of cinnamon oil in order to evaluate its antineoplastic effect on the SKOV-3 cells. The produced NE formulas were physically characterized by the zetasizer. The cytotoxic activities of BLM and NE formulas were examined by CCK-8 kit, Coomassie blue staining for the visualization of the morphological changes, Annexin V-FITC for identifying apoptosis and cell death detection ELISA plus kit for DNA fragmentation measurement. The average droplet diameter of the blank NE (450.90±1.57 nm) was increased when loaded with BLM (522.57±0.85 nm) while the magnitude of the negative zeta potential of the loaded formula (0.381±0.003 mV) was less than the blank NE (1.01±0.020 mV). The potential cytotoxicity of the BLM-NE was significantly greater than the toxicities of the free BLM and blank NE. The blank NE and BLM-NE have the greatest apoptotic effect and higher enrichment factor compared to free BLM. Loading BLM in NE based on cinnamon oil has considerably improved its efficacy as an anticancer drug on the SKOV-3 cells.

Preparation, characterization, and antimicrobial activity of cinnamon essential oil and cinnamaldehyde nanoemulsions

ABSTRACT Cinnamomum verum essential oil and its main component, cinnamaldehyde, were incorporated into nanoemulsions to improve their stability and activity. Oil-in-water (O/W) nanoemulsions were prepared using the high-energy ultra-sonication method. Cinnamon oil nanoemulsion exhibited a more vigorous DPPH radical scavenging activity (IC50 = 1.81 mg/L) than the standard α-tocopherol (IC50 = 9.16 mg/L). Cinnamaldehyde nanoemulsion exhibited the highest antibacterial action against Salmonella typhimurium and Staphylococcus aureus (MIC = 175 and 150 mg/L, respectively). It was also displayed the highest inhibition against Candida albicans (EC50 = 19.92 mg/L). Cinnamaldehyde nanoemulsion was the most active against mycelial growth of Aspergillus flavus and A. niger (EC50 = 38.20 and 134.80 mg/L, respectively). It also presented the highest activity against spore germination. This study describes antimicrobials and antioxidants based on nanoemulsions made from natural products that can be used to treat microbial infections.

Effect of the edible coating containing cinnamon oil nanoemulsion on storage life and quality of tomato (Lycopersicum esculentum Mill) fruits

Tomato is one of the fruit vegetables that had perishable properties so that it needs good postharvest handling to increase their shelf life. One of among other technologies, surface coating of tomatoes with edible ingredients added with natural antimicrobials is potential to be applied. Currently, nanotechnology represents an important area and an efficient option for extending the shelf life of foods. The research aimed to investigate the effect of edible coating, containing cinnamon oil nanoemulsion, to extend the storage life and quality of tomato fruits. Treatments given were (a) dipping time in the edible coating formula (1 and 3 minutes), and the storage period of tomatoes, namely 3, 6, 9, 12 and 15 days at room temperature (27°C). As a control treatment, the inspection was also applied on non-coated tomatoes. The results showed that coating treatment was significantly able to delay changes in the quality attributes of tomatoes and longer shelf life compared to fruit that was not coated with an edible coating. Tomato edible coating has better in maintaining physicochemical characteristics (weight loss of 1.83%, TSS 0.34 Brix, vitamin C 59.8 mg/100g and total plate count of 7.88 × 106 CFU/g) than control throughout the storage period. The study concludes that cinnamon oil nanoemulsion coating could be a good alternative to preserve the quality and extend the storage life of tomatoes.

Lemongrass and cinnamon oil nanoemulsions: Formulation and study of their physical stability and activity against Zygosaccharomyces bailii.

The optimal conditions for elaborating oil/water nanoemulsions of lemongrass (LG), cinnamon bark (CB) and cinnamon leaves (CL) essential oils and their antimicrobial activity against Zygosaccharomyces bailii at pH 4.00 were studied. The effect of the emulsification methodology on the physical stability and antimicrobial activity of the nanoemulsions were also evaluated. Furthermore, the sensory impact of nanoemulsions added to an apple juice was tested. LG and CL nanoemulsions were elaborated by ultrasonication and CB nanoemulsion, by high-speed homogenization. They were stable for at least 120 days at 25 °C. They exhibited antimicrobial activity against Z. bailii being CB the most effective since it showed the smallest MIC value (156.3 mg/l), followed by LG (468.8 mg/l) and CL (1250.0 mg/l). A slight increase in growth rate was observed due to ultrasonication. An additive interaction in relation to the inhibitory effect between LG and CB nanoemulsions against Z. bailii was observed. While nanoemulsions obtained would be used as natural antimicrobial agents in food and beverage products, only LG nanoemulsion at MIC concentration diluted was acceptable in juice showing the sensory impact of essential oils on foods.

Shelf life extension of muffins coated with cinnamon and clove oil nanoemulsions.

Clove and cinnamon based nanoemulsions (NE) were prepared with different levels of soy lecithin as a surfactant employing ultrasonication treatment. Increase in surfactant levels decreased the particle size (PS), polydispersity index (PDI) and zeta potential in both the NE. Cinnamon and clove based nanoemulsions were optimized at 1.5 and 2.0% SL, respectively based on their PS and PDI value. Nanoemulsions having the highest thermo stability were further selected to coat the muffin samples. NE Coated and uncoated muffins were evaluated for changes in density, moisture content, water activity, weight loss, texture, antioxidant activity, microbial activity and sensory scores during storage. NE coating significantly increased antioxidant activity of muffins by 26.89% (Cinnamon oil NE) and 37.31% (Clove oil NE). Furthermore during storage, coating of NE maintains the texture of the muffins, reduce the weight loss, density and moisture content to a greater extent in comparison to uncoated muffins. Antioxidant activity and total plate count of clove oil NE coated muffins were significantly higher than cinnamon oil NE coated muffins and while both the NE coating also effectively facilitated in extending the shelf life up to 6days without any quality deterioration, which facilitated their use as a functional ingredient.

Physical, morphological, and storage studies of cinnamon based nanoemulsions developed with Tween 80 and soy lecithin: a comparative study

The aim of this study was to characterize the ultrasonically formulated cinnamon oil nanoemulsions and to evaluate the effect of type of surfactants [tween 80 (synthetic) and soy lecithin (natural)] and their concentration (oil:tween 80−1:1, 1:2, 1:3 and 1:4 and oil:soy lecithin-1:1, 1:1.5 and 1:2) on the physiochemical properties and stability of nanoemulsions. The physical parameters including particle size, poly dispersity index (pdI), zeta potential, viscosity and turbidity were assessed. Surfactant concentration was found to be inversely correlated with the average particle size as well as pdI of the nanoemulsions. With an increase in the level of surfactant, turbidity of the nanoemulsions was observed to be less due to the smaller average particle size of the developed nanoemulsions. The formulated nanoemulsions were stored at 25 oC and 4 oC and analyzed for turbidity, pH and phase separation upto 90 days. Results revealed that the type and concentration of the surfactant significantly influenced the particle size and stability of nanoemulsions, the least size being attained with tween 80 @1:4 (22.68 nm) and for soy lecithin@ 1:1.5 (75.61 nm). Emulsions formulated with tween were found to be more viscous in comparison to those prepared with soy lecithin. The storage study revealed that prepared tween 80 and soy lecithin based nanoemulsions (stored at 4 oC and 25 oC) remained stable for 3 months without any phase separation.

Phase inversion temperature-fabricated cinnamon oil nanoemulsion as a natural preservative for prolonging shelf-life of chilled Asian seabass (Lates calcarifer) fillets

Phase inversion temperature (PIT)- fabricated cinnamon oil nanoemulsion was investigated for its antimicrobial and antioxidant efficacy to preserve quality and extend shelf-life of Asian seabass (Lates calcarifer) fillet during chilled storage (4 ± 2 °C). The fillets were treated with low and high concentrations of cinnamon oil nanoemulsion (CN) and bulk cinnamon oil (BO), marked as LC-CN, HC-CN, LC-BO, and HC-BO, respectively. The comparative studies were made with the use of commercially used sanitizer, sodium hypochlorite solution (Na-HPW), and untreated samples. During storage, cinnamon oil nanoemulsion was found to be effective in inhibiting the growth of bacteria by 1–3 log CFU/g compared to the control. Cinnamon oil nanoemulsion was also more effective in delaying the production of total volatile basic nitrogen (TVB-N) and lipid oxidation in samples, hence, preserving the sample qualities, especially for color and texture when compared to BO and Na-HPW. The shelf-life of the fillets was 2–4 days for the control and at least 6–8 days for the CN-treated samples. These results indicated that cinnamon oil nanoemulsion could effectively be used as a natural preservative for maintaining quality and extending shelf-life of fish fillets.

Plant Essential Oils Based Nanoemulsion Formulations and Its Antibacterial Effect on Some Pathogens

Antibiotic resistance is the most challenging problem of concern globally and this is invigorating the need of newer antimicrobial products with potential antimicrobial properties. Plant products, especially plant essential oils produce a large array of secondary metabolites as natural antimicrobials. Use of nanotechnology can add advantages to enhance the antibacterial properties of these essential oils. Present study is focused on development of nanoemulsions from plant essential oils and to study their antibacterial activities. Tea Tree Oil, Thyme Oil, Clove leaf and Cinnamon Essential Oils nanoemulsion was formulated using Tween 20 and Tween 80 respectively using probe ultrasonicator. All the formulated Nanoemulsions were then subjected to physicochemical characterization, stability studies and tested for antibacterial activities using Agar-well diffusion method. Stable nanoemulsion formulation with maximum antibacterial activity then subjected to droplet size measurements and polydispersibility index study. Increase in surfactant concentration resulted in reduction in droplet size when ultrasonication time was constant. Cinnamon oil nanoemulsion 20C4 & 80C4 with pdi index 0.573 and 0.382 and droplet size 272.3nm and 133.6 nm respectively demonstrated maximum antibacterial activity in Agar-well diffusion method against S.aureus, E.coli, and S.typhi. When both nanoemulsions were exposed to bacterial growth curve inhibition study. No potential rise in optical density of test pathogens were observed. The inhibition of bacterial growth may be due to killing action of cinnamon oil nanoemulsion formulations to initial bacterial inoculum added to nutrient broth. The study suggests that nanoemulsion formulations from plant essential oils can be used as natural antimicrobials in variety of products.

Cinnamon and clove oil nanoemulsions: novel therapeutic options against vancomycin intermediate susceptible Staphylococcus aureus

Antibiotic resistance is one of the most important public health concerns worldwide. Essential oils especially as micro- and nanoemulsion formulations are emerging as potential agents to target resistant pathogens and as drug delivery vehicles. Cinnamon and clove oils were formulated into nanoemulsions using Brij 35 or Tween 20. Based on the physicochemical characteristics and stability, CiB-3, ClB-3, CiT20-5 and ClT20-5 were identified as optimised emulsions and their anti-Staphylococcal properties were determined. Hydrodynamic diameter of the oil droplets was < 15 nm. The emulsions have only 5% of oil, and there was an 83–166-fold improvement in static MIC over the bulk oil. Inocula ranging from 105 to 107 CFU mL−1 of both MSSA and VISA strains did not significantly affect the activity of all four nanoemulsions. Tween 20 containing nanoemulsions had higher anti-biofilm activity (66–76%) and the activity was comparable between MSSA and VISA. ClT20-5 decreased the viable counts of both strains below detectable limits by 24 h. There was a statistically significant difference in leakage of 260-nm-absorbing cellular components between MSSA and VISA at 30 min (CiB-3: P = 4.67e−013, ClB-3: P = 2.49e−010, CiT20-5: P = 0.00028, ClT20-5: P = 0.00056) and at 60 min (CiB-3: P = 1.37e−014, ClB-3: P = 4.14e−014, CiT20-5: P = 5.30e−012, ClT20-5: P = 2.82e−009). The SEM images of the treated and untreated cells show significant damage and alteration in the morphology of the emulsion treated cells. This study demonstrates the significant anti-Staphylococcal activity of cinnamon and clove oil against MSSA and VISA strains.

Antimicrobial activity of cinnamon oil nanoemulsion against Listeria monocytogenes and Salmonella spp. on melons

Listeria and Salmonella related recalls and outbreaks are of major concern to the melon industry. Cinnamon oil has shown its usefulness in antimicrobial food treatment. However, its applications are limited due to poor solubility of cinnamon oil in water. Utilization of Cinnamon oil nanoemulsion may offer effective antimicrobial treatment to the melon industry. Different formulations of cinnamon oil nanoemulsion were made by ultrasonication using Tween 80 as an emulsifier. The particle size of emulsion was determined by dynamic light scattering. Microbroth dilution assay was performed on Listeria monocytogenes and Salmonella spp. to find out the antimicrobial efficacy of cinnamon oil nanoemulsion. Honeydew and cantaloupe were artificially inoculated with the bacterial strains mentioned above followed by treatment in nanoemulsion (control, 0.1%, 0.25%, and 0.5%) for 1 min. The average diameter of our nanoemulsion was 9.63 ± 0.3 nm. Minimum inhibitory concentration (MIC) of cinnamon oil nanoemulsion for Listeria monocytogenes and Salmonella spp. strains was 0.078% v/v and 0.039% v/v, respectively. Compared to the water control, 0.5% nanoemulsion showed up to 7.7 and 5.5 log reductions in Listeria monocytogenes and Salmonella spp., respectively. The data suggests that cinnamon oil nanoemulsion can be used as an effective natural microbial control agent for melons.

Antimicrobial activity and chemical stability of cinnamon oil in oil-in-water nanoemulsions fabricated using the phase inversion temperature method

The water-dispersibility and antimicrobial activity of cinnamon oil is enhanced by encapsulating it within oil-in-water nanoemulsions. This study investigated the impact of oil phase composition on the minimum inhibitory concentration (MIC) of cinnamon oil nanoemulsions against Escherichia coli, Salmonella enterica serovar Typhimurium (S. Typhimurium), Staphylococcus aureus and Vibrio parahaemolyticus. The nanoemulsions were fabricated using the phase inversion temperature (PIT) method, which simply involves heating a mixture of surfactant, oil, and water about the PIT and then quench cooling with stirring. The antimicrobial activity of cinnamon oil is largely due to cinnamaldehyde, which is highly susceptible to chemical degradation. For this reason, the decrease in cinnamaldehyde content and increase in a major reaction product (benzaldehyde) were measured in the cinnamon oil nanoemulsions during storage. The antimicrobial activity of cinnamon oil nanoemulsions increased (lower MICs) as the droplet size decreased. Cinnamaldehyde was degraded during emulsification and after storage for 31 days. These results have important implications for the improvement of the antimicrobial activity and stability of encapsulated cinnamon oil using nanoemulsion-based delivery systems.

Evaluation of antifungal activity of blended cinnamon oil and usnic acid nanoemulsion using candidiasis and dermatophytosis models

Abstract Fungal infections are one of the most important health issues facing by people since a long time. The objective of the present study was to evaluate antifungal activity of a prepared blended cinnamon oil and usnic acid nanoemulsion (CUN) using candidiasis and dermatophytosis models both in vitro and in vivo. In vitro activity was performed using cup plate method; minimum inhibitory concentrations (MICs) and minimum fungicidal concentrations (MFCs) were determined using brain heart infusion (BHI). In vivo antifungal activity was determined on cutaneous candidiasis in rats and on dermatophytosis guinea pig model. In vitro study of CUN exhibited maximum antifungal activity after 48 h. The maximum zone of inhibition was 1.19 cm for CUN (10 mg/mL), which was near to the fluconazole (1 mg/mL) i.e. 1.82 cm. The MIC of CUN for C. albicans and T. mentagrophytes were 60 and 55 μg/mL, respectively, which was more than cinnamon oil and usnic acid solution (CUS). In vivo study of CUN in cutaneous candidiasis model showed significant antifungal activity. The log colony forming unit per infected site of CUN was 1.36 in comparison to untreated control group (3.91). However, the clinical efficacy profile of CUN on dermatophytosis guinea pig model was more than the standard drug (41.3%) and CUS (35.6%). Its mycological efficacy was 81.4%, which was greater than standard drug (79.6%) and CUS (74.5%). Thus, the present study substantiated that CUN can be used as a feasible formulation for topical application against fungal infections.

Influence of nonionic and ionic surfactants on the antifungal and mycotoxin inhibitory efficacy of cinnamon oil nanoemulsions.

The influence of ionic surfactants (cationic surfactant lauric arginate and anionic surfactant lysolecithin) on the physical properties, antifungal and mycotoxin inhibitory efficacy of Tween 80 stabilized cinnamon oil-in-water nanoemulsions was investigated. Nanoemulsion droplets of similar particle diameter (∼100 nm), but variable electrical characteristics, were formed by mixing 0.1 wt% ionic surfactant with 0.9 wt% Tween 80 before homogenization. The nanoemulsions were physically stable over 28 days at 23 °C. The antifungal activity (against mycelial growth and spore germination) and mycotoxin inhibitory activity of cinnamon oil nanoemulsions bearing positive, neutral, and negative charge surface was then evaluated against two chemotypes of Fusarium graminearum. In general, the cinnamon oil played a decisive role in the resulting antifungal and mycotoxin inhibitory activities. The surfactant charge had a limited impact on the antifungal mycotoxin inhibitory activities of cinnamon oil in the nanoemulsions. Both ionic surfactant-based cinnamon oil nanoemulsions showed greater activity in inhibiting mycelial growth and mycotoxin production of F. graminearum than those based on Tween 80. Treatment of mycelium with cinnamon oil nanoemulsions resulted in the loss of cytoplasm from fungal hyphae, and accounted for the antifungal action. These results have important implications for the design of essential oil based nanoemulsions as effective antifungal delivery systems in foods.

Antimicrobial activity of PIT-fabricated cinnamon oil nanoemulsions: Effect of surfactant concentration on morphology of foodborne pathogens

The impact of surfactant concentration (10 to 20 wt%) on the antimicrobial activity of cinnamon oil nanoemulsions formed by the phase inversion temperature (PIT) method was studied against a number of foodborne pathogens: Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus and Vibrio parahaemolyticus. Minimum inhibitory concentration (MIC), dynamic time kill, and changes in bacteria morphology were determined. Increasing non-ionic surfactant (Tween®80) concentration from 10 to 20 wt% increased the MIC values of the nanoemulsions. However, dynamic time kill plots revealed that nanoemulsions with higher surfactant concentrations (15 and 20 wt%) led to faster or more prolonged inhibition of bacteria compared to those with lower concentration (10 wt%) or with bulk cinnamon oil. Morphological changes of the bacteria were more promoted for nanoemulsions containing higher surfactant concentrations as shown by field emission scanning electron microscopy (FE-SEM). The antimicrobial activity of the cinnamon oil nanoemulsions was attributed to their ability to disrupt bacterial cell wall structures and promote expulsion of internal cellular material.

Essential Oil Nanoemulsions and their Antimicrobial and Food Applications

The consumer awareness for secure insignificantly handled food has constrained the food dealers either to decrease the measure of chemically synthetic antimicrobial substances or to replace them with natural ones. Essential oils (EO) extracted from edible, therapeutic and herbal plants have been well recognized as natural antimicrobial additives. As characteristic then viable antimicrobials, EO have been progressively observed towards control of foodborne microbes and progression of nourishment wellbeing. It is ordinarily hard to achieve high antimicrobial vulnerability when mixing with EO in nourishment based items because of low dissolvability of water and interactive binding. Subsequently, the delivery system of nanoemulsion-based EO is emerging as aviable solution to control the growth of foodborne pathogens. Lipophilic compounds are distributed uniformly in the aqueous phase with the help of nanoemulsion technique. Therefore, the nanoemulsion formulation is generally comprised of mainly three constituents i.e. oil phase, aqueous and a surfactant. Nanoemulsions droplet average diameters should below 100 nm. According to previous studies, the clove, cinnamon and thyme oil nanoemulsions which were formulated with non ionic surfactants (Spans and Tweens) were having droplet size less than 100nm. The current review emphases on essential oil based nanoemulsions which are prepared with different ingredients which hence, enhance the antimicrobial action in food items.