Essential Oil Emulsions Research Articles

Natural cellulosic material characteristics: A possibility to develop antimicrobial active fiber-based packaging

Coconut husk, rubberwood sawdust, and palm leaf base are cellulosic agricultural wastes that have potential to be processed to fiber as absorbing material. This study investigated characteristics (morphological, physiological properties, chemical composition, absorption capacity, and water absorption isotherms) of coconut, rubberwood, and palm fiber. Also, the study aimed to develop an antimicrobial sachet packaging to resist against foodborne pathogens (Listeria monocytogenes, Staphylococcus aureus, Salmonella spp., and Escherichia coli) by adding lime oil (LO) emulsion or Litsea cubeba (LC) oil at 50 to 700 µL into the material (1 g) before, and then dried and placed in the 1-L seal box. Results showed that among the three, coconut performed the best in terms of releasing the essential oil (EO) emulsion against bacteria. Coconut could adsorb and release volatile LO or LC at the lowest concentrations (LO, 500 µL/L; LC, 300 µL/L) to inhibit bacteria compared with the other fibers (700 µL/L) at 35 °C. Results indicated that coconut has a low water absorption rate, which influenced the faster adsorption of EO emulsion in the beginning of the process; therefore, using low concentrations of EO in coconut for bacterial inhibition is possible. Coconut contains 34.5% lignin, 68.7% holocellulose, 37.6% cellulose, and 31.2% hemicellulose. Coconut is suitable as an alternative to the biocomposite material in developing a new antimicrobial packaging design.

Development of cellulose nanocrystal-stabilized Pickering emulsions of massoia and nutmeg essential oils for the control of Aedes albopictus

We investigated the larvicidal potential of 10 plant essential oils (EOs) against the Asian tiger mosquito Aedes albopictus. Among the EOs, larvicidal activity against Ae. albopictus was strongest in those derived from massoia (Massoia aromatica) and nutmeg (Myristica fragrans). Larvicidal activities of massoia and nutmeg EOs against Ae. albopictus were 95.0% and 85.0% at 50 μg/mL, respectively. A total of 4 and 14 compounds were identified from massoia and nutmeg, respectively, and two massoia lactones, C10 and C12, were isolated from massoia EO. Among the identified compounds, benzyl salicylate, terpinolene, C12 massoia lactone, sabinene, benzyl benzoate, methyl eugenol, and C10 massoia lactone exhibited the strong larvicidal activity. Cellulose nanocrystal (CNC)-stabilized Pickering emulsions of massoia and nutmeg EOs were developed to overcome the insolubility of EOs in water. CNC/massoia and CNC/nutmeg emulsions were stable for at least 10 days, and larvicidal activities of CNC/massoia PE and CNC/nutmeg were higher than those of crude massoia and nutmeg EOs. This study presents a CNC-stabilized PE, a suitable formulation for EOs, as a potential larvicide against Ae. albopictus.

Effect of tapioca starch coated-rubberwood box incorporated with essential oils on the postharvest ripening and quality control of mangosteen during transportation

Mangosteen fruit distribution is limited due to their quality, shelf-life and their serious postharvest losses during handling, transportation, and distribution. Application of antimicrobial packaging box in fruit transportation proffers good stacking strength, excellent cushioning, better shelf-life retention and fruit quality for efficient marketing and customer acceptability. Thus, this study was aimed at controlling postharvest ripening and quality of mangosteen fruit during transportation using tapioca starch coated-rubberwood box containing essential oils. Three essential oil treatments namely, 0.8% of essential oil emulsion of peppermint and lime oil at ratio 1:3 (POLO); of peppermint oil (PO); and of lime oil (LO) were, applied on wood box surface. Each box contained 8 kg of mangosteen transported within Thailand by train for 6 days at ambient temperature (~25 ± 3 °C). Mold appearance, ripening stage and the color changes in the fruits were assessed. Other quality parameters including pH, titratable acidity, total soluble solids, total phenolic contents, and fruit firmness of were evaluated before and after transportation. Fruit treated with POLO and PO only attained stage 2 on ripening scale (pink blush on yellow background), while the LO and control group were ripened to stage 4 (red) after transportation. The POLO and PO treatments were more efficient in delaying mold growth, maintained color changes, weight loss, acidity and total soluble solids when compared with other treatments. Total phenolic contents were significantly higher (P < 0.05) with POLO (148.56 ± 0.03) with least value recorded in untreated mangosteen (58.98 ± 0.05). Interestingly, POLO-treated wood box was less subjected to fluctuations in the chemical compositions as displayed by attenuated total reflectance-Fourier transform infrared spectroscopy. Combination of POLO (1:3) incorporated into tapioca starch coating could be applied as a fungicide on rubberwood surface for enhanced antimicrobial activity and in preserving wood quality. Also, shelf-life quality and consumer acceptability of fruit could be preserved during transportation and storage.

Formulation of a Semisolid Emulsion Containing Leptospermum scoparium Essential Oil and Evaluation of In Vitro Antimicrobial and Antibiofilm Efficacy.

Manuka oil, an essential oil derived from the Leptospermum scoparium, has been traditionally used for wound care and as a topical antibacterial, antifungal, and anti-inflammatory. However, the essential oil is not well retained at mucosal sites, such as the oral cavity, where the benefits of the aforementioned properties could be utilized toward the treatment of persistent biofilms. Within this study, L.scoparium essential oil was incorporated into a semisolid emulsion for improved delivery. The safety profile of L.scoparium essential oil on human gingival fibroblasts was determined via cell viability, cytotoxicity, and caspase activation. The minimal bactericidal concentration of L.scoparium essential oil was determined, and the emulsion's antibiofilm effects visualized using confocal laser scanning microscopy. L.scoparium essential oil demonstrated a lower IC50 (0.02% at 48 h) when compared to the clinical control chlorhexidine (0.002% at 48 h) and displayed lower cumulative cytotoxicity. Higher concentrations of L.scoparium essential oil (≥ 0.1%) at 6 h resulted in higher caspase 3/7 activation, suggesting an apoptotic pathway of cell death. A minimal bactericidal concentration of 0.1% w/w was observed for 6 oral bacteria and 0.01% w/v for Porphyromonas gingivalis. Textural and rheometric analysis indicated increased stability of emulsion with a 1 : 3 ratio of L.scoparium essential oil: Oryza sativa carrier oil. The optimized 5% w/w L.scoparium essential oil emulsion showed increased bactericidal penetrative effects on Streptococci gordonii biofilms compared to oil alone and to chlorhexidine controls. This study has demonstrated the safety, formulation, and antimicrobial activity of L.scoparium essential oil emulsion for potential antibacterial applications at mucosal sites.

Characteristics of two cedarwood essential oil emulsions and their antioxidant and antibacterial activities

Cedarwood essential oil (CEO) has the effect of anti-inflammatory and anti-bacteria. However, the application of this essential oil is limited due to its strong volatility and poor water solubility. To address this issue, two types of oil-in-water CEO emulsions including CEO nanoemulsion (CEO-NE) and CEO Pickering emulsion (CEO-PE) were prepared. CEO-NE with 5% surfactant, had a smaller particle size (135.14 ± 1.1 nm) and higher absolute zeta potential value (32.75 mV) compared with CEO-PE (1% starch) which particle size was 626.21 ± 6.05 nm, zeta potential was 27.58 mV. The stability of CEO-NE and CEO-PE were tested by multiple light scattering, results showed that Turbiscan Stability Index (TSI) value of CEO-NE was much lower than that of CEO-PE. CEO-NE and CEO-PE exerted higher free radical scavenging activities, iron reducing power and antibacterial ability than CEO itself. These results indicated that emulsification is a feasible method to extend application of CEO.

Starch-based films enriched with nanocellulose-stabilized Pickering emulsions containing different essential oils for possible applications in food packaging

Consumers are increasingly demanding biodegradable food packaging with a minimal amount of synthetic preservatives and, at the same time, worried about potential contaminants, particularly during any pandemic event. Plant essential oils (EO) are natural compounds with remarkable antimicrobial properties. This study aimed to prepare thermoplastic starch films (TPS) containing nanocellulose-stabilized Pickering emulsions (PE) of different essential oils: ho wood (Cinnamomum camphora), cardamom, and cinnamon, and investigate the suitability of biopolymer films as packaging material. The films were prepared via casting method and were characterized concerning chemical interactions by FT-Raman and FTIR, mechanical, crystallinity, thermal, and water vapor permeability properties. PE Ho wood-starch films showed strong chemical interactions, which significantly improved the film's mechanical resistance. The films with cardamom and cinnamon showed low compatibility, with a decrease in tensile strength. All films showed less crystallinity than the pristine TPS, which can be attributed to the starch chain organization's changes. The films showed high thermal stability due to the strong molecular interactions among starch chains and PE, as confirmed by TGA and DSC analysis. The films' thermal stability is an indication that it can be safely applied in the food industry. Besides, the films showed a lower water vapor transmission rate, and the water may act as a carrier for PE, improving the release of the active compounds. This study reveals the differences between three essential oils incorporated into starch-based films. The ho wood films are the most promising PE to be applied as biodegradable active packaging.

Sanitary and physiological quality of corn seeds (Zea mays) treated with essential oil emulsion

The aim of the present studies were to evaluate the effects of treatments with essential oil emulsion on the sanitary and physiological quality of creole corn seeds. In the studies were evaluated the essential oils of neem (Azadirachta indica), citronella (Cymbopogon nardus), lemon balm (Cymbopogon citratus), melissa (Melissa officinalis L.), and the combinations neem-citronella, neem-lemon balm, neem-melissa, citronella-lemon balm, citronella-melissa and lemon balm-melissa. The tests carried out were germination, length of seedlings (aerial part and root), dry mass and pathology for Fusarium sp and Aspergillus sp, in seeds of creole corn produced without the use of synthetic pesticides. The studies were carried out in vitro and consisted of the preparation of water emulsion, 5,000 ppm of essential oil and 1% of triton X100 and direct application on the seeds of creole corn, following the protocol of Rules of Seed Analysis (RSA). The results showed a significant decrease in the occurrence of fungi Fusarium sp and Aspergillus sp with treatment with essential oils of citronella, lemon balm and melissa, while the oil of neither reduced the occurrence of Fusarium sp, but increased the occurrence of Aspergillus sp in almost four times. All binary combinations of essential oils reduced the occurrence of both fungi. On the other hand, the physiological quality was strongly affected by the death of creole corn seeds, except for the treatment with lemon balm essential oil. Therefore, these studies allow to affirm that essential oils can be efficient in the control of pathogens, however they can kill the seeds of creole corn.

Effect of formulation on properties, stability, carvacrol release and antimicrobial activity of carvacrol emulsions

The structural design of essential oil emulsions can be exploited to modulate their antimicrobial activity, through the effect that the main formulation parameters (oil phase composition and type of emulsifier) have on the release of encapsulated antimicrobial compounds. In this work, different emulsions containing carvacrol, selected as model essential oil component, were characterized in terms of emulsions size, stability, and carvacrol release and solubilization, determined in Franz cells, and tested for minimum inhibitory and microbicidal concentration against P. fluorescens, S. epidermidis, and S. cerevisiae.The results showed that carvacrol fraction in the oil phase significantly affected oil viscosity, density, and O/W interfacial tension. Carvacrol solubilization in the aqueous phase, in equilibrium with the oil mixture, increased with the concentration of carvacrol in the oil phase and with the presence of an emulsifier/stabilizer in the aqueous phase. However, when encapsulated in emulsions carvacrol solubilization exhibited a weak dependence on carvacrol fraction in oil phase because part of the emulsifier/stabilizer was adsorbed at the O/W interface. Higher carvacrol solubilization was observed for WPM Pickering emulsions, followed by WPI and T80 emulsions. The antimicrobial activity was proportional to carvacrol solubilization, suggesting that emulsion droplets act as micrometric tanks for carvacrol, which is steadily released over time in the aqueous phase. The high carvacrol solubilization in the aqueous phase at higher carvacrol fractions in the oil phase (≥75% w/w) was also responsible for lower T80 and WPI emulsion stability because of coalescence, whereas all WPM emulsions exhibited signs of flocculation.

Prevention of Ostwald ripening in orange oil emulsions: Impact of surfactant type and Ostwald ripening inhibitor type

The Ostwald ripening phenomenon, an instability observed in essential oil emulsions, could be controlled by modifying the oil composition. Herein, this study evaluated what types of triglycerides used to modify the oil composition may be more effective in inhibiting Ostwald ripening, and also determined how the interfacial properties of the emulsions affected the efficacy of triglycerides in inhibiting Ostwald ripening. Emulsions were stabilized by emulsifiers with differently sized hydrophilic groups, which correlate to the thickness of the interfacial region, and their oil compositions were varied by mixing triglycerides. Significant increase in droplet size was observed in emulsions prepared using only orange oil during storage. Modifying oil composition by adding medium-chain triglycerides (MCT) or long-chain triglycerides (LCT; corn oil in this study) inhibited droplet growth, and adding triglycerides over 20% into the oil phase prohibited Ostwald ripening. LCT was less efficacious in inhibiting Ostwald ripening than MCT for the same content.

A natural post-emergence herbicide based on essential oil encapsulation by cross-linked biopolymers: characterization and herbicidal activity.

This work describes efforts to encapsulate savory (Satureja hortensis L.) essential oil (EO) with different natural polymers (i.e., Arabic gum/gelatin (AGG), apple pectin (AP), gelatin (G)) and, as a separate set of experiments, with bio cross-linkers (i.e., citric acid and transglutaminase enzyme). The phytotoxic activity of encapsulated savory EO on tomato (Lycopersicon esculentum Mill.) and amaranth weed (Amaranthus retroflexus L.) was investigated. The micro-capsules were evaluated in terms of size, polydispersity, stability, encapsulation efficiency, morphology, and release properties. The Korsmeyer-Peppas model operated when EO was being released from the micro-capsules. Carvacrol (52.5%) and γ-terpinene (30.2%) comprised the main constituents of the savory EO. Based on the results, encapsulating the EO with cross-linked biopolymers increased the stability and herbicidal activity of EO, as compared to simple EO emulsions. Maximum toxicity injuries (MTI) were caused by encapsulations of apple pectin, cross-linked with APe enzyme (15ml/L) on both plant species. MTI were observed 2days after using the micro-encapsulated herbicides (MCHs). However, the injury caused by MCHs on tomato was not significant. The lowest values of fresh weight (2.80g), chlorophyll a (0.194mg/g Fw), and total chlorophyll content (0.219mg/g Fw) of amaranth occurred in response to APe (15ml/L). Moreover, using AP(e) (10ml/L) caused the lowest values of starch (0.444mg/g Fw) and flavonoid contents (4.18mg Cat/g Fw) in amaranth which measured as 59% and 90% reductions, respectively, in comparison with the control. The highest values of MDA (0.0109nmol/g Fw) and H2O2 (0.0432μmol/g Fw) were observed in amaranth plants treated with AP(e) (10ml/L). In summary, cross-linked apple pectin can perform well in slow release delivery systems of agrochemicals. It can be recommended for use in the production of commercial, EO-based natural herbicides.

The physiochemical and preservation properties of fish sarcoplasmic protein/chitosan composite films containing ginger essential oil emulsions

AbstractActive films with essential oils have attracted more attention in recent years. In order to improve the solubility and stability of ginger essential oil (GEO) in film forming solutions, GEO coarse emulsion and nanoemulsions were prepared named CGEO (z‐average = 799.53 nm), NGEO‐1 (z‐average = 114.71 nm) and NGEO‐2 (z‐average = 59.30 nm), respectively. And the effect of concentration (0.5% and 1.0% v/v) and particle sizes of GEO emulsions on the physiochemical and preservation properties of fish sarcoplasmic protein and chitosan blend based edible films were studied in this study. The elongation at break significantly (p &lt; .05) increased after adding GEO emulsions, and the light transmittance, water vapor permeability and water solubility were the lowest when NGEO‐2 was incorporated into films. The antioxidant and antimicrobial activities of films were concentration‐dependent. Furthermore, all the films were applied into packaging red sea breams fillets, and the results of total viable counts, pH and thiobarbituric acid demonstrated that SP‐CH films with GEO emulsions, especially nanoemulsions obviously prolonged the shelf‐life of fillets during 4°C.Practical ApplicationsIn recent years, the research about incorporating essential oils into edible films to prepare active edible films due to their antimicrobial and antioxidant properties have been more documented. In this study, fish sarcoplasmic protein and chitosan were chosen as film‐forming materials to prepare active films with ginger essential oil emulsions. The physicochemical, mechanical, optical properties of films showed that the films have the basic characteristics as food packaging materials. The releasing and antioxidant property of films indicated that the active films have a potential application in packaging food which was easy oxidized. The basic properties of films combined with oxidation indicators (total viable count, pH and thiobarbituric acid reactive substances) would provide the scientific basis for developing active films and their application for food packaging, such as seafood, meat, fruits and vegetables.

Preparation of cinnamon essential oil emulsion by bacterial cellulose nanocrystals and fish gelatin

This study was aimed at preparing nanoemulsions with bacterial cellulose nanocrystals (BCNCs) and cinnamon essential oil (CEO) with and without fish gelatin. The effect of CEO concentration (0.2, 0.4, 0.8, 1.57, 2.34 and 3.1% v/w) and pH (3.5 and 5) on the droplet size, ζ-potential, morphology, and encapsulation efficiency (EE) of CEO/BCNC emulsions was investigated. It was observed that ζ-potential was approximately −25 mV for the BCNC emulsions, whereas it changed to positive values (from approximately 4 mV–12 mV) in the systems containing gelatin (3% w/w). In addition, in the presence of gelatin, emulsions exhibited larger droplets (450–1000 nm) than did the CEO/BCNC emulsions (350–550 nm), as demonstrated by transmission electron microscopy. TEM analysis also revealed the surfactant activity of gelatin, which displaced between the hydrophobic CEO nanodroplets and the more polar BCNCs. The effect of pH on EE was significant for the emulsions in the presence of gelatin in that EE was higher at pH 5 than at pH 3.5 up to a CEO concentration of 0.24% w/v. Finally, a direct relationship was established between CEO concentration and EE for emulsions with and without gelatin.

EMULSIONS OF ORANGE AND COCONUT OILS AND THEIR USE IN PEANUT BUTTERS

In this study, orange essential oil and coconot oil emulsions and their mixtures were prepared and added to peanut butter to prevent lipid oxidation. Sodium caseinate was used as an emulsifier and ultrasonication was used for homogenization. Emulsions containing orange essential oil had a higher total phenolic content and antioxidant capacity than the coconut oil emulsions (P&amp;lt;0.05). TBARS values of the peanut butters containing ultrasonicated emulsions were considerably higher than the other treatments (P &amp;lt;0.05) at the end of storage (20th day). Samples containing ultrasonicated emulsions had lower L* (lightness) values than the other samples (P &amp;lt;0.05). Results showed that addition of these emulsions into peanut butters was effective in suppressing the lipid oxidation, but still further research is needed to produce the emulsions in nanoscale so as to increase the antioxidant properties of the oils.

Insecticidal Activity of Commiphora erythraea Essential Oil and Its Emulsions Against Larvae of Three Mosquito Species.

The use of essential oils as ecofriendly tools for vector management is one of the mainstreams for biopesticide research. We evaluated the larvicidal properties of Commiphora erythraea (opoponax) essential oil and its fractions against Culex restuans Theobald, Culex pipiens L., and Aedes aegypti L. The use of bio-based amylose-N-1-hexadecylammonium chloride inclusion complex (Hex-Am) and amylose-sodium palmitate inclusion complex (Na-Palm) as emulsifiers for C. erythraea essential oil was also investigated. Bisabolene was the most abundant chemical constituent in the whole essential oil (33.9%), fraction 2 (62.5%), and fraction 4 (23.8%) while curzerene (32.6%) and α-santalene (30.1%) were the dominant chemical constituents in fractions 1 and 3, respectively. LC50 values for the whole essential oil were 19.05 ppm for Cx. restuans, 22.61 ppm for Cx. pipiens, and 29.83 ppm for Ae. aegypti and differed significantly. None of the four C. erythraea essential oil fractions were active against mosquito larvae. Two CYP450 genes (CYP6M11 and CYP6N12) and one GST gene (GST-2) were significantly upregulated in Ae. aegypti larvae exposed to C. erythraea essential oil suggesting their potential involvement in metabolic pathways for C. erythraea essential oil. Essential oil emulsions produced with Hex-Am were more toxic than the whole essential oil while those produced with Na-Palm had similar toxicity as the whole essential oil. These findings demonstrate that C. erythraea essential oil is a promising source of mosquito larvicide and that the use of Hex-Am as an emulsifier can enhance the insecticidal properties of C. erythraea essential oil.

Antimicrobial and antioxidant coating based on basil seed gum incorporated with Shirazi thyme and summer savory essential oils emulsions for shelf-life extension of refrigerated chicken fillets

The present study was conducted to evaluate the effects of antimicrobial and antioxidant coatings based on basil-seed gum (BSG) on the refrigerated shelf-life of chicken fillets. Antimicrobial and antioxidant properties were developed by incorporating summer savory essential oil (SEO) and Shirazi thyme essential oil (TEO) emulsions, individually or in combination with each other, into BSG coating. Microbiological evaluations including total viable count (TVC), psychrotrophic (PBC) and lactic acid bacteria counts (LAB), as well as chemical charachteristics namely peroxide value (PV), thiobarbituric acid (TBA), total volatile basic nitrogen (TVB-N) and pH were performed on coated and control samples. Moreover, sensory evaluations were performed for odor, color, texture and overall acceptability. Results showed that incorporating SEO and TEO into BSG coatings could significanty (p < 0.5) increase the quality of chicken fillets. Antimicrobial and antioxidant coatings significantly (p < 0.05) reduced pH, TVB-N, PV and TBA values compared to uncoated control samples, specially for BSG/TEO coated samples, which resulted the best treatment. pH, TVB-N, PV and TBA in BSG/TEO coated samples were 5.96, 16.84, 3.33 and 2.44, respectively, lower than those of uncoated control samples on day 12 of storage. A similar reduction trend was observed for microbial population. TVC, PBC and LAB were 3.69, 4.73, and 3.87 log CFU/g on day 12 of storage in BSG/TEO coated samples lower than those of uncoated samples. Therefore, the natural active components of EOs showed positive effects on extending the shelf-life of coated chicken fillets. Besides, sensory properties of coated samples were significantly (p < 0.05) better than those of control samples. Generally, TEO was more effective than SEO and no synergistic effect was observed between TEO and SEO.

In-vitro (2D and 3D cultures) and in-vivo cytotoxic properties of Zataria multiflora essential oil (ZEO) emulsion in breast and cervical cancer cells along with the investigation of immunomodulatory potential

Ethnopharmacological relevanceZataria multiflora is an iranian valuable traditional plants, called Avishan Shirazi in Persian language used to reduce inflammation, spasm, pain, and cancer symptoms. Zataria essential oil (ZEO) is one of the essential oils possessing broad biological activities. Aim of the studyThe aim was to investigate the anticancer effects of ZEO both in-vitro and in-vivo using mouse mammary carcinoma 4T1 cell line and mouse cervical cancer TC1 cell line. Material and methodsThe in-vitro effects of ZEO on the proliferation of these cell lines were considered in 2D and 3D culture by MTT assay. In the following, to indicate death mode, fluorescence staining, AnnexinV/PI flowcytometry and caspase-3 activity assay of monolayer cells treated with ZEO was done. In order to evaluate the antitumor activities of ZEO, tumor-bearing BALB/c and C57BL/6 mice were intraperitoneally administered with ZEO and the immunomodulatory effects of ZEO were considered through cytokine assay. Additionally, hematobiochemical factors including aspartate aminotransferase and alanine aminotransferase were investigated to confirm the harmless effects of ZEO. ResultsThe In-vitro results showed that treatment of cells with ZEO leads to significant inhibition of 4T1 and TC1 cell proliferation and apoptosis in monolayer cell culture (2D) and multicellular spheroids (3D). Based on In-vivo results, ZEO was effective in decreasing the tumor weight compared to the control. Furthermore, ZEO was effective in tilting the balance of cytokines in favor of T helper 1 through the increase in the secretion of TNF-α, IFN-γ, IL-2 and decrease in IL-4. During the treatment with ZEO, hematobiochemical factors of mice did not significantly change. Conclusionthe present study demonstrated that the ZEO has potent antiproliferative, apoptosis-inducing and immune system stimulant properties in breast and cervical cancer.

Formulation and assessment of nano-encapsulated bioherbicides based on biopolymers and essential oil

Excessive uses of chemical pesticides have resulted in the occurrence of a wide array of problems consequently using plant natural products is gaining more attention. In this study, different concentrations of savory (Satureja hortensis L.) essential oil (control, 5, 10 and 15 ml/L) were nano-encapsulated using Arabic gum (AG), Persian gum/gelatin (PGG), Persian gum (PG) as wall materials. The nanocapsules had their herbicidal activity against tomato (Lycopersicon esculentum Mill.) and amaranth (Amaranthus retroflexus L.) evaluated by measuring 18 physiological and biochemical parameters. The average size of the nanocapsules varied between 81 and 208 nm, while polydispersity index showed variation between 0.210 and 0.536. The encapsulation efficiency of nanoparticles varied between 72.1–92.8 %. Nano-encapsulated herbicides (NCHs) stability was investigated for 42 days and a mathematical model was followed during oil release. Nano-encapsulated herbicides showed considerable herbicidal activity against amaranth while they had a mild effect on tomato. Moreover, herbicidal activity results exhibited the improvement of encapsulated savory essential oil (EO) efficiencies as compared to non-nano EO emulsion (without polymer). The greatest and fastest injury to amaranth caused by encapsulated EO using cross-linked Persian gum at 15 ml/L which asserted 100 % weed control after 48 h. The aforementioned data suggest the encapsulation of essential oils by biopolymers and with the help of cross-linkers can be used as a valuable tool for the production of organic, natural herbicides.

Characterization of chitosan based polyelectrolyte films incorporated with OSA-modified gum arabic-stabilized cinnamon essential oil emulsions

Octenyl succinic anhydride (OSA) modified gum arabic (GA) was synthesized and used as an emulsifier to stabilize cinnamon essential oil (CEO) emulsions. The structure and properties of chitosan based polyelectrolyte films incorporated with above OSA-GA stabilized CEO emulsions were investigated. Results showed that OSA modification introduced the hydrophobic groups, which greatly influenced the emulsification capability of GA. The antimicrobial activities of CEO emulsions were significantly enhanced by the synergistic effect of GA modification and ultrasonic treatment. When the proportions of CEO emulsion increased, the improved water barrier properties but deteriorated tensile properties of films were observed. The retention of CEO during storage was prolonged to 20 days and the release of CEO in food simulant was effectively inhibited as emulsion ratios increased to 20%, indicating the effectiveness of the system for CEO delivery. As a result, the antimicrobial activities of films significantly enhanced with the innovative incorporation of OSA-GA stabilized CEO emulsions.

Treatment of fresh water hyacinth with essential oil emulsion and subsequent use of the plant material for control of Aspergillus flavus on rice dessert products

Essential oil emulsion, which is generally functionalized to have increased antifungal activity, has high solubility in water. The objective of this research was to develop an essential oil emulsion for absorption by water hyacinth plants in order to produce an essential oil absorbent material as a carrier of essential oil vapor that can be released to control mold in an enclosed packaging system. The fresh water hyacinth adsorbed the Michelia alba oil emulsion (100 µL/mL to 500 µL/mL) through its root system, transporting it to the stems and leaves after submerging the plant into the M. alba oil emulsion for 48 h. Dried sections (root, stem, and leaf) of the water hyacinth plant with absorbed M. alba essential oil emulsion released the M. alba vapor, inhibited Aspergillus flavus growth on malt extract agar (MEA), and also Thai dessert (Ja Mongkut) with the highest antifungal activity achieved with the concentration 500 µL/mL. The maximum essential oil absorption (345 µL/g) in the fresh plant was achieved after 48 h. The dried water hyacinth (≥ 0.4 g/L air) completely inhibited the growth of A. flavus for at least 7 days. In addition, the absorbent material prevented the growth of A. flavus on the Thai dessert (Ja Mongkut) with approximately 100% effectiveness (versus the control) for 10 days, thereby extending the shelf-life 2.5-fold in when compared with the control without essential oil.

Antiparasitic effects of Zataria multiflora essential oil nano-emulsion on larval stages of Echinococcus granulosus.

Various protoscolicidal agents are indicated for the prevention of recurrence of cystic echinococcosis caused by the larval stage of Echinococcus granulosus; however, most of these chemicals have adverse side effects. This study evaluated the effects of Zataria multiflora essential oil (ZEO) nano-emulsion and emulsion at the concentrations of 1, 2, 5, 10, 15, and 20µl/ml on E. granulosus protoscoleces. Albendazole (5mg/ml), normal saline, and nano-emulsion without ZEO served as control groups. Optimal concentrations of ZEO nano-emulsion and emulsion on the microcysts were also investigated. ZEO emulsion at a concentration of 20µl/ml for the duration of 15min and nano-emulsion for the duration of 10min resulted in the death of 100% of the protoscoleces. Additionally, densely packed aggregates were formed inside the microcysts treated with ZEO nano-emulsion and emulsion at a concentration of 20µl/ml after 40min, but the complete destruction of laminated layers did not occur. The results indicate that ZEO nano-emulsions have a higher protoscolicidal effect than its emulsion, but these two compounds had similar effects on microcysts.