Tea Tree Essential Oil Research Articles

Screening of Essential Oils for the Inhibition of Enterobacter ludwigii Isolated from Tomato Fruits

Tomato is perishable and requires preservation to extend its shelf life. In this study, we conducted selection processes to identify essential oils that can help to avoid spoilage and deterioration during tomato storage and extend the shelf life. Thereafter, we determined the phosphatase activity assay, potassium ion concentration, and electron microscopy to study the antibacterial mechanism of essential oil. We found that Enterobacter ludwigii W01 was the dominant spoilage bacterium in tomatoes with cracked and curled skin. We selected oregano essential oil from 12 essential oils (oregano essential oil, lemon essential oil, osmanthus essential oil, cypress wood essential oil, tea tree essential oil, licorice essential oil, Baili essential oil, white camphor essential oil, Shancang seed essential oil, rosemary essential oil, rose essential oil, and cinnamon essential oil) which could significantly inhibit the activity of E. ludwigii W01. However, the diameter of the inhibition zone for Wh, Te, Cy, Li, Rm, Le, and Os is 0 mm, the diameter of the inhibition zone for Ba, Sh, and Ro was less than 1.0 mm, whereas the diameter of the inhibition zone for Ci and Or was greater than 2.0 mm. The diameter of the suppression circle for Ci and Or was greater than 2.0 mm, while Ci was lesser than Or. Oregano essential oil can damage the cell wall of E. ludwigii W01, leading to the leakage of the alkaline phosphatase stored between the cell wall and the cell membrane which can increase the alkaline phosphatase activity in the bacterial solution. Meanwhile, the addition of oregano essential oil significantly altered the cellular morphology of E. ludwigii W01. Spraying the surface of fresh tomato fruits with 1 MIC (0.125%) of oregano essential oil prolonged the storage time to 15 days, without significant changes in its sensory attributes. Those results indicated that oregano essential oil was a potential preservative for tomatoes.

Metal-organic frameworks-based moisture responsive essential oil hydrogel beads for fresh-cut pineapple preservation

The preservation of fresh-cut fruits and vegetables has attracted attention to the shelf-life reduction caused by high humidity. Herein, alginate/copper ions cross-linking, in-situ growth and self-assembly techniques of metal-organic frameworks (MOFs) were utilized to prepare a moisture responsive hydrogel bead (HKUST-1@ALG). As the multistage porous structure formation, tea tree essential oil (TTO) load capacity in hydrogel bead (TTO-HKUST-1@ALG) was increased from 6.1% to 21.6%. TTO-HKUST-1@ALG had excellent moisture response performance, and the release rates of TTO increased from 33.89% to 70.98% with moisture increasing from 45% to 95%. Besides, TTO-HKUST-1@ALG exhibited excellent antimicrobial, antioxidant capacity, and biocompatibility. During storage, TTO-HKUST-1@ALG effectively improved the cell membrane integrity by maintaining the balance of reactive oxygen species metabolism. The degradation of cell wall structure and tissue softening were delayed by inhibiting the cell wall-degrading enzymes activity. Briefly, TTO-HKUST-1@ALG improved the storage quality and extended shelf-life of fresh-cut pineapple, which was a promising preservative.

Poly(acid lactic)-montmorillonite clay bionanocomposites loaded with tea tree oil for application in antibacterial wound healing

This study evaluated the ability of tea tree essential oil (TT) incorporated into polymer-clay bionanocomposites to in vitro eliminate resistant microorganisms towards applications in antibacterial wound healing. Antimicrobial bionanocomposites were prepared in two steps, namely sonication and melt intercalation, and montmorillonite clay and poly(acid lactic) (PLA) were chosen because they constitute a polymer-clay bionanocomposite to be applied in wound dressing. X-ray diffraction (XRD) results indicated good incorporation of the organic compounds, TT oil, and glycerol (G) (the latter used as a plasticizer) into the clay galleries. Dynamic-mechanical analysis (DMA) results showed a 2–30 % increase in storage modulus and up to 10 °C decrease in glass transition temperature, proving the influence of both TT oil and G on the stress transfer of the reinforcement clay phase. Thermogravitmetric analyses (TGA) revealed TT oil and G addition worsened the thermal stability of the bionanocomposites, which show a mass loss onset decrease up to 90 °C and a clay content between 1.5 and 3 wt%. In vitro antimicrobial activity tests revealed only the combinations of TT oil and G reduced Escherichia coli and Staphylococcus aureus satisfactorily and showed the antimicrobial activity of the bionanocomposites.

Morphological, molecular, and biological characterization of bulb rot pathogens in stored Lanzhou lily and the in vitro antifungal efficacy of three plant essential oils.

Lanzhou lily (Lilium davidii var. willmottiae) is an exclusive sweet lily variety indigenous to China, which is susceptible to bulbous rot caused by fungal infection during storage. This experiment tests the pathogenicity of the pure culture isolated from the diseased tissue was confirmed in accordance with Koch's postulates, and the pathomycetes were identified based on their morphological and molecular characteristics. Furthermore, the biological characteristics of the pathogens were investigated, followed by an evaluation of the antifungal effects of three plant essential oils against them. The results showed that two strains of fungi were isolated from Lanzhou lily rot, which were identified as Fusarium oxysporum Schl. and Aspergillus sydowii (Bain. Et sart.). In addition, the pathogenicity of these two strains of fungi was demonstrated that only F. oxysporum induced rot with similar symptoms during the post-harvest storage period. The biological characteristics of F. oxysporum indicated the potato maltose agar and lily dextrose agar were identified as the most suitable media. Sucrose was determined to be the optimal carbon source, while ammonium nitrate was found to be the best nitrogen source for the growth of F. oxysporum. Mycelial growth and sporulation of F. oxysporum occurred at an optimum pH value of 6. Total darkness facilitated mycelial growth and conidial germination. The ideal temperature for growth was found to be 28°C, while relative humidity did not significantly impact mycelial growth; however, a relative humidity of 55% was most favorable for spore production. Among the three essential oils tested, cinnamon essential oil displayed superior antifungal efficacy against F. oxysporum, whereas angelica essential oil and tea tree essential oil also exhibited moderate inhibitory effects against this pathogen. This research provides valuable theoretical insights for disease control during the storage and transportation of Lanzhou lily.

Enhancing anesthesia and minimizing toxicity: evaluation of clove, Cinnamon, and tea tree essential oils in nile tilapia (Oreochromis niloticus)

Enhancing anesthesia and minimizing toxicity: evaluation of clove, Cinnamon, and tea tree essential oils in nile tilapia (Oreochromis niloticus)

The influence of plant scents on nest box inspection by Eastern Rosella (Platycercus eximius)

ABSTRACT Many cavity nesters add volatile plants with medicinal properties to their nests. In Australia, eucalyptus and tea-trees are highly volatile plants, which have antiparasitic and antimicrobial properties. Here, we tested whether scents of eucalypt (Eucalyptus polybractea) and tea tree (Melaleuca alternifolia) essential oils can attract birds to newly installed nest boxes. Twenty-four nest boxes received three scent treatments (eucalypt, tea tree, control) for 10 days each using a Latin-square design. Bird visitation was recorded using camera traps. Eastern Rosellas (Platycercus eximius) visited the nest boxes the most (1,454 visits) and were therefore the focus of the study. Eastern Rosellas did not change their behaviours in response to the eucalypt scent in nest boxes: there was no difference in visitation, duration of visits or nest box inspection behaviour between nest boxes with eucalypt scent and those with the control scent. However, Eastern Rosellas visited nest boxes with tea tree scent less frequently and spent less time at these boxes than those with the control scent. The mean time that Eastern Rosellas spent inspecting boxes slightly increased over the 10-day period following scent placement at boxes with control and eucalypt scents, while it sharply decreased at boxes with tea tree scent. This is the first study demonstrating that an Australian bird detected and behaved differently in response to plant volatiles. The use of scents may offer opportunities to not only attract, but potentially also deter certain birds from using particular hollows.

ОПЫТ ЛЕЧЕНИЯ ПОСЛЕРОДОВОГО ЭНДОМЕТРИТА У КОРОВ

The purpose of the study is to conduct a comparative analysis of the therapeutic effectiveness of a local antiseptic drug based on tea tree essential oil for acute postpartum catarrhal endometritis in cows. The study was conducted at the Department of VNB, Obstetrics and Physiology of Farm Animals of the Krasnoyarsk State Agrarian University, on the basis of the dairy farm of the Balakhta District of the Krasnoyarsk Region. The object of the study is red-motley cows. Research methods: obstetric and gynecological medical examination of breeding stock; the diagnosis of acute postpartum catarrhal-purulent endometritis was established during a clinical and gynecological examination of fresh cows, which inclu-ded thermometry, rectal and vaginal examination. The diagnosis was considered confirmed when pathological discharge of a catarrhal nature appeared from the uterus during rectal massage. Two experimental groups of fresh cows were formed according to the principle of analogues (based on live weight, age, lactation, clinical manifestation of the form of acute endometritis). In the 1st experimental group, scheme № 1 was used: a 25 % oil solution of tea tree essential oil was administered intrauterinely in a dose of 20 ml daily once a day until clinical recovery; eleovit 8 ml was administered intramuscularly on the 1st and 5th days of treatment; uteroton 10 ml was administered intramuscularly daily once a day for 3 days; 0.05 % chlorhexidine solution 200 ml – intravaginally; rectal massage of the uterus once a day. In the 2nd experimental group, treatment regimen № 2 was used, which differed from regimen № 1 by using a 50 % oil solution of tea tree essential oil in a similar dosage. The best therapeutic effect in the treatment of acute catarrhal endometritis was obtained using scheme № 2 using a 50 % oil solution of tea tree essential oil. Du¬ring the seven-day course of treatment, therapeutic effectiveness was obtained in 60.0 % of cases; prolongation of the course of therapy led to the recovery of all animals in this experimental group. The ave¬rage duration of treatment for the group was 8.0 days.

Sustainable Approach to Development of Antimicrobial Textile Pads for Sweat Absorption

Double-layered textile sweat-absorbing underarm pads with a natural antimicrobial treatment can be used to solve the problem of the wetness sensation in the case of increased physical activity or hyperhidrosis. In addition, changeable antimicrobial active underarm pads help to decrease the number of clothing washings, i.e., reducing water consumption and pollution. Another aspect of sustainability is that the underarm pads can be produced from clothing production waste. The moisture absorption capability of six hydrophilic cellulose-based knitted fabrics and two hydrophobic synthetic woven fabrics was investigated. It was found that the best result for next-to-skin moisture absorption and next-to-clothing protection against moisture penetration was achieved by using a double-layered underarm pad composed of a cotton-based fleece knitted structure in the next-to-skin layer and a very thin and tight 100% PA woven fabric in the outer layer. Four samples of impregnated liquid with herbal extracts and essential oils were prepared, and antimicrobial activity was evaluated using the discus method. Textile impregnated with tea tree essential oil, nutmeg, and birch extracts had the highest antimicrobial activity against Gram-positive bacteria—Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus cereus.

Multifunctional gelatin nanoparticle stabilized-Pickering emulsion hydrogel based on dextran and amikacin with controlled drug release and enhanced antibacterial capability for promoting infected wound healing

Plant essential oils possess broad-spectral antimicrobial property, but the applications are impeded by their insolubility in water, extreme volatility, and strong irritation. Nanoparticle-stabilized emulsion (Pickering emulsion) gels are colloidal systems with ability to accommodate two immiscible phases in one system. The thick adsorption nanoparticle layers and the cross-linked networks in continuous phase could provide protective barriers for antibacterial oil and achieve on-demand controlled release. An emulsion hydrogel templated from gelatin nanoparticle-stabilized emulsion is one-pot constructed by conducting a tunable cross-linking process between oxidized dextran (Odex) and amikacin in the continuous phase and concomitantly trapping tea tree essential oil (TO) droplets in the three-dimensional network. The resulted emulsion hydrogel presents tunable gelation time, adequate mechanical strength, fascinating injectability, and self-healing capability. It is pH-responsiveness and presents controlled release of amikacin and TO, exhibiting a long-term bacteriostasis of 144 h. The emulsion hydrogel facilitates the outstanding wound healing efficiency in 14 days (95.2 ± 0.8 % of wound closure), accompanied with enhanced collagen deposition and angiogenic activities. The incorporation of TO into emulsion hydrogel system reduced its irritation and improved its biosafety, showing potential application in bacteria inhibition even as implants in vivo.

Decoding a novel green and effective antimicrobial agent: Glycerol monolaurate stable in nanosystem

Food microbiological control is the key to protecting food quality. However, glycerol monolaurate (GML), as a generally recognized safe antimicrobial agent, limits its antibacterial activity due to its poor water solubility. Ultrasound-assisted construction of essential oil nanosystems is an ingenious way to solve the above problems. In this study, essential oil-based nanoemulsions (NEs) were constructed by replacing traditional oil phase with tea tree essential oil (TTO) stabilized GML and enhanced antibacterial properties. The results demonstrated that uniform droplets could only be formed when the GML content in the nanosystem was below 50 mg/mL. NEs showed favorable optical properties with a turbidity below 0.1 and a whiteness index below 35, and they were Newtonian fluids (viscosity <0.005 Pa s). Besides, the nanosystem exhibited excellent stability even at extreme pH (1 or 11) and high salt ion concentration (500 mM), where droplet sizes of above system were still less than 100 nm after 15 d. Notably, GML alone cannot exert effective antibacterial effects against E. coli and S. aureus, whereas the encapsulation of GML into the nanosystem allowed it to exert antibacterial activity successfully. Banana was selected to validate the availability of NEs, and the treated groups maintained their attractive appearances and quality after 20 d. Overall, this work developed a new nanosystem to stabilize GML, allowing it to exert antimicrobial activity effectively.

Bio-based nanomaterial suspensions as sprayable coatings for maintaining blueberry postharvest quality

The growing concerns about postharvest fruit spoilage demand sustainable active coating materials with high performance. In this work, bioactive spray coating suspensions were developed for the postharvest preservation of blueberries using chitosan, cellulose, and lignocellulose nanofibers (ChNFs, CNFs, and LCNFs), sodium alginate (SA), and tea tree essential oil (TTO). Characteristics, including the rheological properties of coatings and the effect on physicochemical postharvest quality parameters of blueberry fruit were investigated. The nanomaterials and SA were shown to make stable and sprayable coating suspensions with high surface charge (zeta potential value of −61.3 mV), shear thinning behavior, steady viscosity, and outstanding viscoelastic behavior from their ability to restore fibrous network structure and ion strength of SA to inhibit nanofibers aggregation. The coatings with LCNFs and SA were more effective in retarding moisture loss of postharvest blueberries during storage compared with coatings without LCNFs and SA. Blueberries coated with ChNF/LCNF/SA/TTO had a soluble solids content (SSC) increase of 16.2% after 15 storage days, while uncoated and other coated blueberries had more than a 21.7% SSC increase. In addition, the ChNF/LCNF/SA/TTO coating had an entangled matrix structure and enhanced hydrophobicity, improving gas barrier performance on the blueberry surface. As a result, the coating was able to preserve the moisture, stiffness, firmness, and individual sugar contents of blueberries during storage. Utilizing nanomaterials and other natural polysaccharides in coatings can offer an economically feasible and sustainable approach for functionalizing biomass materials to preserve fruits.

Development of Antibacterial Thermoplastic Starch with Natural Oils and Extracts: Structural, Mechanical and Thermal Properties.

In this study, the influence of the incorporation of eucalyptus (EO), tea tree (TT) and rosemary (RO) essential oils and Chiriyuyo extract (CE) on the structure and properties of thermoplastic starch (TPS) obtained from potato starch, glycerin and water was evaluated. All oils and the extract were used at a concentration of 0.5 g/100 g of TPS, while for TT, the effect of the concentration was also studied. The mixtures obtained were processed by extrusion and thermocompression molding. The sheets were characterized by XRD, FTIR, TGA, SEM and analyses of their mechanical properties, antimicrobial characteristics and biodegradability. The results show that the use of small concentrations of the oils in 70TPS does not induce changes in the TPS structure according to the results of XRD, FTIR and TGA, with each essential oil and CE affecting the mechanical properties unevenly, although in all cases, antimicrobial activity was obtained, and the biodegradability of TPS in soil was not modified. An increase in the concentration of TT in 60TPS causes marked changes in the crystallinity of TPS, providing a greater modulus with a higher concentration of TT. Regardless of the amount of TT, all sheets maintain antimicrobial characteristics, and their biodegradation in soil is delayed with a higher oil content.

A synergistic anti-bacterial and anti-adhesion activity of tea tree (Melaleuca alternifolia) and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils on Legionella pneumophila

Legionella pneumophila is a Gram-negative bacterial pathogen that colonizes natural and artificial water systems and has the ability to form a biofilm. The biofilm protects L. pneumophila from various environmental factors and makes it more resistant to chlorine-based disinfectants. This study investigated the anti-bacterial properties of tea tree (Melaleuca alternifolia (Maiden and Betche) Cheel) oil and lemon eucalyptus tree (Eucalyptus citriodora Hook) essential oils (EOs) and their synergistic, additive inhibitory and anti-adhesive effects against L. pneumophila biofilm formation on polystyrene. The minimum effective concentration (MEC) for tea tree is 12.8 mg ml−1 and for lemon eucalyptus tree EO 6.4 mg ml−1. In the checkerboard assay, different combinations of these two EO show synergistic and additive anti-microbial activity. The minimum anti-adhesive concentration (MAC) for tea tree is 12.8 mg ml−1 and for lemon eucalyptus tree EO 6.4 mg ml−1. A combination of 3.2 mg ml−1 tea tree EO and 0.8 mg ml−1 lemon eucalyptus tree EO showed the strongest anti-adhesive effect against L. pneumophila on polystyrene. The tested oils and their combination showed intriguing potential to inhibit L. pneumophila biofilm formation.

Effectiveness of Tea Tree (Melaleuca alternifolia) Essential Oil and Jojoba Carrier Oil through Topical Application on the Relief of Allergies Caused by Aeroallergens

Background: Allergies are one of the most common chronic conditions worldwide. Due to the cost and possible side effects of pharmacologic treatments, aromatherapy, an alternative method in relieving allergies was studied. Objective: This study aimed to determine the effectiveness of Jojoba Oil and 100% Tea Tree Essential Oil combination through topical application as an alternative method for relieving severity and frequency of allergic symptoms triggered by aeroallergens. Methods: A pre-experimental one-group pre-test and post-test research design was used to determine whether the combination of Tea Tree and Jojoba Oil produced an effect to the respondents’ allergic signs and symptoms. A modified 3-part questionnaire was used to gather data from thirty (30) purposively selected college students. Results: It appeared that the combination oil when applied topically resulted to a reduction in the severity and frequency of the allergic symptoms; specifically watery eyes, nasal congestion, runny nose, nasal itching, sneezing, coughing, chest tightness, wheezing, shortness of breath and phlegm production. The observed alleviation of symptoms is deemed significant with P-values less than 0.05, except for the reduction in the frequency of wheezing (P-value=.101&gt;0.05) and shortness of breath (P-value=.053&gt;0.05) nonetheless. Conclusion: Hence, the combination oil composed of Tea Tree essential oil with 2% dilution and Jojoba carrier oil when applied topically to the hot spots of the body reduces allergic symptoms. Nurses and other public healthcare providers can consider aromatherapy in the treatment regimen of individuals who have allergies but prefers to manage it non-pharmacologically or does not have access to anti-allergy medications.

Antifungal activity of essential oils of tea tree, oregano, thyme, and cinnamon, and their components

Antifungal activity of essential oils of tea tree, oregano, thyme, and cinnamon, and their components

Design of gum Arabic/gelatin composite microcapsules and their cosmetic applications in encapsulating tea tree essential oil.

Microencapsulation has been widely used to protect essential oils, facilitating their application in cosmetics. In this study, gelatin, gum arabic and n-butyl cyanoacrylate were used as wall materials, and composite microcapsules of tea tree essential oil (TTO) were prepared using a combination of composite coagulation and in situ polymerization methods. When the ratio of gelatin to gum arabic is 1 : 1, the ratio of TTO to n-butyl cyanoacrylate is 4 : 1, the curing time is 10 h, and the encapsulation efficiency (EE) under these conditions is 73.61%. Morphological observation showed that the composite capsule was a micron-sized spherical particle with an average particle size of 10.51 μm, and Fourier transform infrared spectroscopy (FT-IR) confirmed a complex coagulation reaction between gelatin and gum arabic, and the disappearance of the n-butyl cyanoacrylate peak indicated that the film was formed in a condensation layer. The thermogravimetric analysis (TGA) results showed that the composite capsule greatly improved the thermal stability of TTO. Rheological testing showed that the viscosity and viscoelasticity of the surface composite capsules have been improved. In addition, the composite capsule showed good stability in the osmotic environment and has good sustained-release performance and antioxidant capacity in the average human skin environment.

Production of Mono-Hydroxylated Derivatives of Terpinen-4-ol by Bacterial CYP102A1 Enzymes.

CYP102A1 from Bacillus megaterium is an important enzyme in biotechnology, because engineered CYP102A1 enzymes can react with diverse substrates and produce human cytochrome P450-like metabolites. Therefore, CYP102A1 can be applied to drug metabolite production. Terpinen-4-ol is a cyclic monoterpene and the primary component of essential tea tree oil. Terpinen-4-ol was known for therapeutic effects, including antibacterial, antifungal, antiviral, and anti-inflammatory. Because terpenes are natural compounds, examining novel terpenes and investigating the therapeutic effects of terpenes represent responses to social demands for eco-friendly compounds. In this study, we investigated the catalytic activity of engineered CYP102A1 on terpinen-4-ol. Among CYP102A1 mutants tested here, the R47L/F81I/F87V/E143G/L188Q/N213S/E267V mutant showed the highest activity to terpinen-4-ol. Two major metabolites of terpinen-4-ol were generated by engineered CYP102A1. Characterization of major metabolites was confirmed by liquid chromatography-mass spectrometry (LC-MS), gas chromatography-MS, and nuclear magnetic resonance spectroscopy (NMR). Based on the LC-MS results, the difference in mass-to-charge ratio of an ion (m/z) between terpinen-4-ol and its major metabolites was 16. One major metabolite was defined as 1,4-dihydroxy-p-menth-2-ene by NMR. Given these results, we speculate that another major metabolite is also a mono-hydroxylated product. Taken together, we suggest that CYP102A1 can be applied to make novel terpene derivatives.

Damage reduction of Acromyrmex lobicornis in Pinus ponderosa using mixed pine species in combination with push–pull tools

Abstract Leaf‐cutting ants (LCAs) cause significant damage to forest plantations and are mainly managed by broad‐spectrum synthetic insecticides. In Patagonia, Pinus ponderosa (Pinales: Pinaceae) (Douglas 1836) and Pinus contorta (Pinales: Pinaceae) (Dluglas 1838) are the predominant pine species in forest plantations. Previous research has shown that dehydrated citrus pulp is an LCAs attractant, and tea tree essential oil acts as an LCAs repellent. We evaluated the use of dehydrated citrus pulp and tea tree oil to manage LCAs behaviour in a push–pull setting, using mixed pine species in small plot fields, to reduce the LCA Acromyrmex lobicornis (Hymenoptera: Formicidae) (Emery, 1888) damage in young P. ponderosa plants. We combined the treatment with attractant and repellent in a mono‐specific plantation design (three ponderosa plants surrounded with pulp and three sprayed with tea tree extract) or mixed plantation designs (three contorta plants with pulp and three ponderosa plants with tea tree). The combination of both mono‐specific and mixed plantations with push–pull stimuli delayed discovery and decreased the damage in pines sprayed with the repellent. Mono‐specific as well as mixed species designs were equally effective, reducing ant damage and increasing ~50% the survival probability of P. ponderosa when push–pull stimuli were applied. The use of a push–pull strategy with plant‐based compounds provides potential as a management tool that reduces and delays LCA damage in pine trees.

Utilizing intramammary Melaleuca alternifolia as an organic internal sealant for dry-off therapy in Murrah buffaloes.

The effects of intramammary dry cow therapy based on the administration of 5% Melaleuca alternifolia tea tree essential oil (TTO) as an internal teat sealant to Murrah cows were evaluated. A longitudinal prospective and retrospective negative control study was performed using 12 buffaloes from a total of 20 Murrah buffaloes on an organic farm, with the cow used as a control for herself. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for treatments with pure oil (TTO) and medication containing 5% TTO (O5) were determined. The buffaloes were clinically examined, and the teats were evaluated using thermography and ultrasound. Udder health was monitored during the first 100days in milk (DIM) using milk somatic cell count (SCC) and California mastitis test (CMT). Laboratory tests against standard strains Staphylococcus aureus ATCC®25,923™, Escherichia coli ATCC®25,922™, and wild bacterial strains showed maximum MIC values of 50 µL/mL for the TTO and O5 treatments. One wild-type S. aureus strain showed no MBC. No adverse effects were observed after the intramammary application of TTO. The CMT and SCC values were similar (P > 0.05) for all observations. The medication containing 5% TTO was effective in vitro and compatible with the intramammary tissue in vivo of Murrah buffaloes. TTO was safe, not inducing inflammatory processes or other modifications of the teat detectable by thermography or ultrasound. It was able to protect buffaloes during the dry period under field conditions, demonstrating potential use as a teat sealant for organic farms.

Full-scale determination of essential oil diffusion: Impact on indoor air quality

Essential oils have attracted increasing interest, as they inhibit the metabolic functions of microorganisms. Essential oils are claimed to improve indoor air quality through passive remediation and purifying activities. However, the impact of diffused essential oils on indoor air quality has not been clearly established from a VOC point of view. This study aims to assess the emissions produced by terpene molecules in tea tree essential oil by employing two types of widespread diffusers under real conditions using a full-scale experimental room (40 m3). The emissions generated by terpenoid volatile organic compounds (TerVOCs) are different depending on the type of diffuser. The relative contributions of individual terpenes in the gas phase vary throughout the diffusion process. The impact of tea tree essential oil diffusion on indoor air quality varies from 6 h to 51 days, depending on the diffusion device. Concentration levels can exceed European recommended exposure levels by more than one order of magnitude. Interestingly, the volume of the emission chamber directly impacts the emission dynamics of essential oil constituents. Small chambers may limit the volume of air to be contaminated and possibly impacts the magnitude of concentration gradients during diffusion. This work evidences the interest of using full-scale experimental facilities to determine accurate emission rates. A full-scale experimental methodology including data treatment is validated in this work. Through the proposed protocol, representative emission factors can be determined to assess exposure and perform indoor air modelling.