Essential Oil Vapours Research Articles

Study and optimization of the selectivity of an odorant binding protein-based bioelectronic nose

Over the past two decades, the use of odorant-binding proteins (OBPs) for the development of biosensors and bioelectronic noses (bioeNs) aimed at detecting and analyzing volatile organic compounds (VOCs) has been the subject of considerable research. However, there is a lack of fundamental studies for better understanding the interaction between OBPs and VOCs in gas phase. In this work, we investigated the effect of two key factors, namely relative humidity (RH) level and immobilization technique, on the selectivity of two OBP-based biosensors in gas phase. Concerning the effect of RH, the results showed that our active OBP (wild-type rat OBP3) lost its selectivity at 0% RH but retained good selectivity at 30% and 50% RH. To better understand the effect of this parameter, the hydration mechanism of the OBP was studied both experimentally and through molecular dynamics simulations. The effect of a cysteine residue, genetically added to the N-terminus of OBPs to control their orientation after immobilization on the chip, was evaluated. A significant reduction in selectivity was observed in the absence of cysteine. As expected, the introduction of this amino acid enabled to control the orientation of OBPs, making their binding pocket more accessible to VOCs and favoring specific interactions. Furthermore, we demonstrated that combining OBP-based biosensors with different properties can improve the discrimination capability of our bioeN. Finally, the ability of our system to detect essential oil vapors was tested, providing preliminary evidence that our bioeN is capable of detecting VOCs in complex media.

Inactivation of Listeria monocytogenes on a laboratory medium and enoki mushrooms using organic acid and essential oil vapors

The aim of this study was to determine the antimicrobial activity of organic acid (OA) and essential oil (EO) vapors against Listeria monocytogenes on a laboratory medium and enoki mushrooms. Among 14 OA and 8 EO vapors tested, 3 OA vapors (acetic, formic, and propionic acid) and 3 EO vapors (cinnamon bark, citronella, and lemongrass) showed relatively strong antilisterial activity. On tryptic soy agar (TSA), all three OA vapors had a minimum inhibitory concentration (MIC) of 12.5 mg/L, while the minimum lethal concentration (MLC) of formic acid vapor was the lowest, at 50 mg/L, followed by acetic acid vapor (200 mg/L) and propionic acid vapor (400 mg/L). The MIC values of lemongrass, cinnamon bark, and citronella EO vapors were 25, 100, and 100 mg/L, respectively. The MLC of lemongrass EO vapor was 100 mg/L and MLCs of other EO vapors were >400 mg/L. Formic acid and lemongrass EO vapors showed a partial synergism on TSA (fractional inhibitory concentration index of 0.7500). For L. monocytogenes inoculated on enoki mushrooms, formic acid vapor at a concentration of ≥50 mg/L, as well as formic acid and lemongrass vapors in combination (1:2 vol ratio) at ≥ 75 mg/L, inactivated L. monocytogenes. These results indicate that formic acid vapor is effective at controlling the growth of L. monocytogenes on enoki mushrooms.

Efficacy of Essential Oil Vapours in Reducing Postharvest Rots and Effect on the Fruit Mycobiome of Nectarines.

Nectarines can be affected by many diseases, resulting in significant production losses. Natural products, such as essential oils (EOs), are promising alternatives to pesticides to control storage rots. This work aimed to test the efficacy of biofumigation with EOs in the control of nectarine postharvest diseases while also evaluating the effect on the quality parameters (firmness, total soluble solids, and titratable acidity) and on the fruit fungal microbiome. Basil, fennel, lemon, oregano, and thyme EOs were first tested in vitro at 0.1, 0.5, and 1.0% concentrations to evaluate their inhibition activity against Monilinia fructicola. Subsequently, an in vivo screening trial was performed by treating nectarines inoculated with M. fructicola, with the five EOs at 2.0% concentration by biofumigation, performed using slow-release diffusers placed inside the storage cabinets. Fennel, lemon, and basil EOs were the most effective after storage and were selected to be tested in efficacy trials using naturally infected nectarines. After 28 days of storage, all treatments showed a significant rot reduction compared to the untreated control. Additionally, no evident phytotoxic effects were observed on the treated fruits. EO vapors did not affect the overall quality of the fruits but showed a positive effect in reducing firmness loss. Metabarcoding analysis showed a significant impact of tissue, treatment, and sampling time on the fruit microbiome composition. Treatments were able to reduce the abundance of Monilinia spp., but basil EO favored a significant increase in Penicillium spp. Moreover, the abundance of other fungal genera was found to be modified.

Essential oil vapour inclusion in protective atmosphere packaging for shelf‐life management of fisheries

SummaryFish is well known for its perishable nature. Essential oils in food packaging seem to be safe and reliable both in terms of safety for the consumer and in terms of improving the shelf life of the product. This study aimed to evaluate the effects of two different essential oil vapours (one with rosemary and the other one with lemon extract) on three different types of fishery products (swordfish steaks, bluefin tuna steaks and Argentinian prawns) stored in a protective atmosphere packaging, monitoring the shelf life up to 8 days through microbiological, chemical and sensorial analyses. The results showed that the products preserved with the inclusion of essential oils have reached the end of the shelf‐life period respecting the process hygiene and food safety criteria, receiving a greater appreciation rating from the consumer panel at the end of shelf life for the prawns and swordfish samples with the addition of rosemary essential oils vapours, which instead highlighted the worst result at the end of shelf life for tuna.

Antibacterial Activity of Oregano (Origanum vulgare L.) Essential Oil Vapors against Microbial Contaminants of Food-Contact Surfaces.

The antimicrobial effect of eight essential oils' vapors against pathogens and spoilage bacteria was assayed. Oreganum vulgare L. essential oil (OVO) showed a broad antibacterial effect, with Minimum Inhibitory Concentration (MIC) values ranging from 94 to 754 µg cm-3 air, depending on the bacterial species. Then, gaseous OVO was used for the treatment of stainless steel, polypropylene, and glass surfaces contaminated with four bacterial pathogens at 6-7 log cfu coupon-1. No viable cells were found after OVO treatment on all food-contact surfaces contaminated with all pathogens, with the exception of Sta. aureus DSM 799 on the glass surface. The antimicrobial activity of OVO after the addition of beef extract as a soiling agent reduced the Sta. aureus DSM 799 viable cell count by more than 5 log cfu coupon-1 on polypropylene and glass, while no viable cells were found in the case of stainless steel. HS-GC-MS analysis of the headspace of the boxes used for the antibacterial assay revealed 14 different volatile compounds with α-Pinene (62-63%), and p-Cymene (21%) as the main terpenes. In conclusion, gaseous OVO could be used for the microbial decontamination of food-contact surfaces, although its efficacy needs to be evaluated since it depends on several parameters such as target microorganisms, food-contact material, temperature, time of contact, and relative humidity.

Determination of chemical composition and insecticidal potential of leaf essential oil of Mentha piperita L.

Pulverised fresh Mentha piperita leaves was subjected to hydrodistillation for three hours in a Clevenger-type apparatus. The oil obtained was characterised using Gas Chromatography-Mass Spectrometry (GC-MS) and also evaluated for insecticidal activity on Callosobruchus maculatus (bean weevils) and Sitophilus zeamais (maize weevils). The oil afforded a yield of 0.78% (w/w). A total of 39 compounds were identified from their mass spectra representing 98.9% of the oil. The classes of compounds identified revealed predominance of oxygenated monoterpenoids (72.4%), hydrogenated monoterpenoids accounted for 6.0%, hydrogenated sesquiterpenoids and oxygenated sesquiterpenoids constituted 12.2 and 4.0% respectively. Other non-terpenic compounds detected in the oil accounted for 4.3% of the total oil. The most abundant compound was menthol (40.4%), other major compounds identified were menthone (12.3%), menthofuran (9.2%), 1, 8-cineole (5.6%) and limonene (5.5%). The percentage mortality of between 68-94.5% and 65-90.2% were recorded for bean weevils and maize weevils respectively after exposure to 10µl essential oil vapour in fumigation chambers for 6, 12, 18 and 24 hours. The insecticidal activity of the oil compared favourably with that of standard insecticide and so can be used to formulate an alternative insecticide from botanical source.

A combinatorial approach of Monarda citriodora essential oil (MEO) and linalool vapors to control fruit rot of Citrus limon caused by a new pathogen, Aspergillus foetidus, and its underlying mode of action.

Citrus limon (lemon) is a widely cultivated citrus fruit. Significant postharvest losses due to fungi plague its production. Environmental and human health hazards have made the application of synthetic fungicides unsuitable. Despite the previous reports of antifungal activities of essential oil (EO) vapors, their synergistic combinations are understudied. Synergistic vapor combinations are advantageous due to less concentration of active components. This study aimed to isolate and identify postharvest fungal pathogens lemon and to evaluate the antifungal effects of synergistic Monarda citriodora EO (MEO)-constituent vapor combinations in vivo and in vitro. Postharvest fungal pathogens of lemon (C. limon) were isolated from various infected samples. The most pathogenic isolate was identified through morphology and its ITS-based rRNA gene sequencing as Aspergillus foetidus (O4). This is the first report of A. foetidus as a postharvest pathogen of lemon. The minimum fungicidal concentrations (MFCs) of MEO vapors treatment against O4 were 1346.15µL/L air. For carvacrol, hexanal, and linalool, MFC was same (96.16µL/L air). Checkerboard assays demonstrated that 1/4 MFC of MEO (336.54µL/L air) and 1/4 MFC of linalool (24.04µL/L air) (M+L) were synergistic against O4. M+L vapors reduced the O4 growth on lemons during storage by 64%±1.50% and preserved their quality (low weight loss %, unchanged pH, increased ascorbic acid content). Propidium iodide staining, ergosterol content analysis, calcofluor white staining and chitin content analysis revealed the integrity loss of the O4 plasma membrane and cell wall. 2',7'-Dichlorofluorescin diacetate staining revealed accumulation of intracellular reactive oxygen species (ROS), and scanning electron microscopy (SEM) analysis exposed the M+L treated mycelia with malformations. M+L vapors offer protection for lemons from A. foetidus and preserve their quality during storage.

The antifungal mechanism of Monarda citriodora essential oil, hexanal and their combined vapours on Aspergillus foetidus

BackgroundThe increased reliance on synthetic fungicides for managing postharvest pathogens resulted in the rise of fungicide-resistant pathogen strains. Previous studies have reported essential oils (EOs) as a promising alternative to synthetic fungicides. However, higher concentrations are required for their practical application, which can alter the taste profile of the stored produce. Synergistic combinations of EO volatiles can reduce the active concentrations, thereby mitigating undesirable taste profile changes. However, very few studies have emphasised the changes in the mode of action of EO volatiles when applied as a synergistic combination. This study aimed to decipher the mode of action of Monarda citriodora essential oil (MEO) and hexanal vapour combination (M + H) against the newly identified postharvest pathogen of apple Aspergillus foetidus. ResultsThe M + H vapour treatment synergistically inhibited the spore germination of A. foetidus at the concentration of 144.23 μL L−1 air (MEO) and 96.15 μL L−1 air (hexanal). Propidium Iodide staining and ergosterol content analysis revealed that vapours compromised the plasma membrane integrity. Hence, there was an extracellular leakage of cytoplasmic components, reduced extracellular pH and increased conductivity. Furthermore, calcofluor white staining showed reduced fluorescence intensity, indicating a compromised cell wall. Reduced chitin content in the cell walls of vapour treated mycelia authenticated the results. 2′,7′-Dichlorofluorescin diacetate (DCFDA) staining revealed the generation and accumulation of Reactive Oxygen Species (ROS) within the vapour treated mycelia. ConclusionThe accumulated ROS interferes with ergosterol and chitin synthesis leading to the collapse of the plasma membrane and cell wall; consequently, extracellular leakage occurs.

Essential Oil Vapors Assisted Plasma for Rapid, Enhanced Sanitization of Food-Associated Pathogenic Bacteria

Essential Oil Vapors Assisted Plasma for Rapid, Enhanced Sanitization of Food-Associated Pathogenic Bacteria

Unravelling molecular mechanisms involved in resistance priming against downy mildew (Plasmopara viticola) in grapevine (Vitis vinifera L.)

Downy mildew (DM; Plasmopara viticola) is amongst the most severe fungal diseases in viticulture and the reason for the majority of fungicide applications. To reduce synthetic and copper-based fungicides, there is an urgent need for natural alternatives, which are being increasingly tested by the industry and the research community. However, their mode of action remains unclear. Therefore, our study aimed to investigate the transcriptomic changes induced by oregano essential oil vapour (OEOV) in DM-infected grapevines. OEOV was applied at different time points before and after DM infection to differentiate between a priming effect and a direct effect. Both pre-DM treatment with OEOV and post-infection treatment resulted in a significant reduction in DM sporulation. RNA-seq, followed by differential gene expression and weighted gene co-expression network analysis, identified co-expressed gene modules associated with secondary metabolism, pathogen recognition and response. Surprisingly, the molecular mechanisms underlying the efficiency of OEOV against DM appear to be independent of stilbene synthesis, and instead involve genes from a putative signalling pathway that has yet to be characterized. This study enhances our understanding of the molecular regulation of innate plant immunity and provides new insights into the mode of action of alternative natural antifungal agents.

Fabrication of Bio-Nanocomposite Packaging Films with PVA, MMt Clay Nanoparticles, CNCs, and Essential Oils for the Postharvest Preservation of Sapota Fruits.

Sapota is an important climacteric fruit with limited shelf life. A special system must be employed to extend the shelf life of sapota fruits. In the present study, polyvinyl alcohol (PVA) and montmorillonite clay (MMt)-based bio-nanocomposite films (BNFs) were integrated at various concentrations (2%, 4%, 6%, and 8%) into cellulose nanocrystals (CNCs), produced from garlic peels (GPs). The BNF loaded with 8% CNC has a better crystallinity index and mechanical properties than the other concentrations of CNC. Therefore, the 8% CNC-incorporated BNF (BNF-8) was selected for further packaging studies. The combined effect of BNF-8 with ajwain essential oil (AO) and oregano essential oil (OO) vapors and BNF-8 with carbendazim (commercial fungicide-CARB) were investigated. In this study, the BNF-based packagings are categorized into five types, viz: BNF+8% CNC (BNF-8), BNF-8+AO, BNF-8+OO, BNF-8+CARB and the non-packaged fruits (control). The shelf-life duration, antioxidant activity, firmness, decay index, and sensory quality were evaluated in order to identify the effectiveness of packaging treatment on sapota fruits. BNF-8+CARB, BNF-8+AO, and BNF-8+OO packaging extended the shelf life of sapota fruits to up to 12 days and maintained the overall physiochemical parameters and sensory qualities of the fruits. Therefore, the BNF-8+AO and BNF-8+OO packaging materials are appropriate alternatives to commercial fungicides for the preservation of sapota during postharvest storage.

Effects of lemon or cinnamon essential oil vapor on physicochemical properties of strawberries during storage

Recently, consumers have gained an interest in natural and minimally processed foods, inciting the food industry to consider using of natural products as preservatives. Strawberries are a widely consumed fruit but are also highly perishable. Therefore, in this study, the physicochemical properties of strawberries (Fragaria×ananassa) were evaluated after a 12-h treatment with lemon essential oil (Citrus×limon) or cinnamon essential oil (Cinnamomum cassia) vapor during storage at 22°C for 4 days in an accelerated shelf-life study and 4°C for 18 days in a validation study. Weight loss was blunted in fruit treated with oil vapor during the first days of storage (p<0.05). Lemon essential oil delayed fruit darkening (p<0.05) but reduced the firmness of strawberries (p<0.05). Strawberries treated with cinnamon essential oil had a higher concentration of reducing sugars (p<0.05), and a decrease of 16.7% visible decay, although the difference was insignificant. Oil vapor treatment did not alter the pH, organic acid content, or soluble solid content during storage compared to the control. Since lemon and cinnamon essential oils have well-documented antimicrobial properties, they may be suitable for the natural preservation of fruit. This study provides new information on using essential oil vapor treatment to preserve fruits, and potentially decrease fruit loss and waste.

Influence of diluent on antimicrobial activity of cinnamon bark essential oil vapor against Staphylococcus aureus and Salmonella enterica on a laboratory medium and beef jerky

The influence of chemical diluents on the antimicrobial activity of plant essential oil (EO) vapors was evaluated. We first determined if vapors generated from 22 chemical diluents not containing EO had antimicrobial activities. Ethyl ether vapor retarded the growth of S. aureus. The minimal inhibitory concentrations (MICs) and the minimal lethal concentrations (MLCs) of cinnamon bark EO vapor, which was diluted in and generated from 21 diluents, against S. aureus and S. enterica were determined. Cinnamon bark EO vapor showed significantly (P ≤ 0.05) lower MICs against S. aureus when diluted in dimethyl sulfoxide (DMSO), ethanol, ethyl acetate, or jojoba oil, and against S. enterica when diluted in DMSO, ethanol, or jojoba oil, compared to those in other diluents. We compared antimicrobial activities of cinnamon bark EO vapor diluted in DMSO, ethanol, ethyl acetate, or jojoba oil against S. aureus and S. enterica on beef jerky as a food model. Antimicrobial activity was significantly (P ≤ 0.05) higher when vaporized from DMSO. These results indicate that antimicrobial activity of cinnamon bark EO vapor may vary significantly (P ≤ 0.05) depending on the type of diluent from which it is vaporized. These observations provide basic information when developing food and food-contact surface decontamination strategies using EO vapors.

Cinnamon essential oil vapor alleviates the reduction of aroma-related volatiles in cold-stored "Feicheng" peach using HS-GC-IMS.

"Feicheng" peach is popular for its unique aroma, but its defect of being highly sensitive to chilling injury (CI) often leads to aroma loss and internal browning. Essential oils (EOs) are often used to enhance the antioxidant capacity of plants and fruits, as well as to trigger their defense against biotic/abiotic stresses. This study aimed to examine the effect of cinnamon essential oil (CEO) vapor treatment on the aroma quality of peach fruit during cold storage using HS-GC-IMS. The results showed that 50 μL/L CEO vapor reduced the severity of internal browning (IB) in peaches at the stage of 7 ~ 21 d during refrigeration (Significantly, the L* value was higher and the IB index was lower than that of control, p < 0.05). Meanwhile, the evident reduction or loss of aroma content caused by CI was restored to a higher level than the control (p < 0.05). Furthermore, CEO treatment promoted the release of aroma-related volatiles as evidenced by more propyl acetate, and the dimer of amyl acetate, isoamyl acetate, butyl acetate detected than that on harvest day and no-treated group after 21 d of cold storage plus 2 d of shelf life. Genes of PpLOX1, PpLOX2, PpHPL1 and PpADH1 associated with aroma-related volatile biosynthesis revealed higher transcript abundance in peach fruits treated with CEO than the control (p < 0.05). Overall, our study demonstrated that CEO in vapor phase may be beneficial to alleviate the quality deterioration in aroma and flesh color of "Feicheng" peaches caused by CI, which lays a theoretical reference for maintaining postharvest quality of peach fruits.

Validation of Broth Macrodilution Volatilization Method for Testing of Essential Oils in Liquid and Vapor Phase: Chemical Composition, Cytotoxicity, and Antibacterial Effect of Indian Medicinal Plants against Pneumonia-Causing Pathogens.

Essential oils (EOs) have great potential in inhalation therapy for the treatment of respiratory infections. However, innovative methods for evaluation of antimicrobial activity of their vapors are still needed. The current study reports validation of the broth macrodilution volatilization method for assessment of the antibacterial properties of EOs and shows the growth-inhibitory effect of Indian medicinal plants against pneumonia-causing bacteria in liquid and vapor phase. Among all samples tested, Trachyspermum ammi EO exhibits the strongest antibacterial effect against Haemophilus influenzae, with minimum inhibitory concentrations of 128 and 256 µg/mL in the liquid and vapor phases, respectively. Furthermore, Cyperus scariosus EO is found to be nontoxic to normal lung fibroblasts assessed by modified thiazolyl blue tetrazolium bromide assay. Chemical analysis performed using gas chromatography-mass spectrometry identified α-citral, cyperotundone, and thymol as the main constituents of Cymbopogon citratus, C. scariosus, and T. ammi EOs, respectively. In addition, β-cymene is identified as the major compound of T. ammi EO vapors when analyzed using solid-phase microextraction and gas-tight syringe sampling techniques. This study demonstrates the validity of the broth macrodilution volatilization method for antimicrobial screening of volatile compounds in the vapor phase and suggests the therapeutic potential of Indian medicinal plants in inhalation therapy.

Antimicrobial effects of essential oil vapors on Bacillus cereus on nutrient agar and iceberg lettuce

We investigated the antimicrobial effects of essential oil (EO) vapors individually and in combination against Bacillus cereus. In an initial study, EO vapors were generated from 95 commercially available EOs and their antimicrobial activities against B. cereus were tested. Five EO vapors (citronella, lemongrass, may chang, oregano, and thyme thymol) showed strong inhibitory activity. Next, we determined the minimal inhibitory concentrations (MICs) and minimal lethal concentrations (MLCs) of these EOs against B. cereus cultured on nutrient agar; values were 0.0781 μL/mL and >5 μL/mL, respectively. The synergistic antimicrobial activity of combinations between EO vapors on B. cereus were evaluated using a modified checkerboard assay. Oregano and thyme thymol EO vapors showed greatest synergism (fractional inhibitory concentration index: 0.5000 at a 1:1 vol ratio). Finally, we tested for antimicrobial properties of oregano and thyme thymol EO vapors against B. cereus on iceberg lettuce individually and in combination. The growth of B. cereus was inhibited by 0.0049–0.0098 μL/mL of EO vapors at concentrations 8- to 16-fold lower than that of MICs on nutrient agar. However, a combination of oregano and thyme thymol EO vapors did not have a synergistic lethal effect. Observations provide basic information for the development of decontamination treatments to inhibit the growth of B. cereus and perhaps other spore-forming bacteria on foods and food-contact surfaces using EO vapors.

Inhibitory effect and underlying mechanism of cinnamon and clove essential oils on Botryosphaeria dothidea and Colletotrichum gloeosporioides causing rots in postharvest bagging-free apple fruits.

Bagging-free apple is more vulnerable to postharvest disease, which severely limits the cultivation pattern transformation of the apple industry in China. This study aimed to ascertain the dominant pathogens in postharvest bagging-free apples, to evaluate the efficacy of essential oil (EO) on inhibition of fungal growth, and to further clarify the molecular mechanism of this action. By morphological characteristics and rDNA sequence analyses, Botryosphaeria dothidea (B. dothidea) and Colletotrichum gloeosporioides (C. gloeosporioides) were identified as the main pathogens isolated from decayed bagging-free apples. Cinnamon and clove EO exhibited high inhibitory activities against mycelial growth both in vapor and contact phases under in vitro conditions. EO vapor at a concentration of 60 μL L-1 significantly reduced the incidence and lesion diameter of inoculated decay in vivo. Observations using a scanning electron microscope (SEM) and transmission electron microscope (TEM) revealed that EO changed the mycelial morphology and cellular ultrastructure and destroyed the integrity and structure of cell membranes and major organelles. Using RNA sequencing and bioinformatics, it was demonstrated that clove EO treatment impaired the cell membrane integrity and biological function via downregulating the genes involved in the membrane component and transmembrane transport. Simultaneously, a stronger binding affinity of trans-cinnamaldehyde and eugenol with CYP51 was assessed by in silico analysis, attenuating the activity of this ergosterol synthesis enzyme. Moreover, pronounced alternations in the oxidation/reduction reaction and critical materials metabolism of clove EO-treated C. gloeosporioides were also observed from transcriptomic data. Altogether, these findings contributed novel antimicrobial cellular and molecular mechanisms of EO, suggesting its potential use as a natural and useful preservative for controlling postharvest spoilage in bagging-free apples.

Impact of essential oil vapors inhalation on blood pressure in patients with hypertension

To perform the comparative study of antihypertensive effects of inhalation with EO vapors of various composition. The investigation included 849 women aged 55-89 years with hypertension. Two examination series were done: 10- and 20-minute duration procedures. Trial subjects were divided into control (psychorelaxation procedure) and experimental (psychorelaxation procedure combined with the EO inhalation of common basil, Italian immortelle, clove tree, common hyssop, cardamom, coriander, Caucasian nepeta, nepeta cataria, spicate lavender, bay laurel, the sort «Oxamitov» of brook-mint, the sorts «Prilutskaya», «Udaichanka», «Ukrainian» of pepper mint, the Siberian fir, Tauric wormwood, the sort «Crimean red» of rose, rosmarinus officinalis, Scotch pine, fennel, mountain savory, garden savory and clary sage; EO concentration in air - 1 mg/m3) groups. Systolic and diastolic blood pressure, heart rate were measured, as well as the coefficient of blood circulation efficiency and Robinson index were calculated before and after the examination in trial subjects. It has been established that the EO of clary sage, bay laurel, Caucasian nepeta and the sort «Oxamitov» of brook-mint have antihypertensive action at both 10-minute and 20-minute exposure. The antihypertensive action of EO of common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis, garden savory was found after 10-minute exposure. There was no antihypertensive action in EO application of Italian immortelle, common hyssop, spicate lavender, the sorts «Prilutskaya», «Ukrainian», «Udaichanka» of pepper mint, Siberian fir, tauric wormwood, Scotch pine and fennel. The EO vapors' inhalation of clary sage, bay laurel, Caucasian nepeta, the sort «Oxamitov» of brook-mint, common basil, clove tree, coriander, nepeta cataria, the sort «Crimean red» of rose, rosmarinus officinalis and garden savory can be a promising method to reduce blood pressure in patients with hypertension.

Evaluation of effects of essential oil vapors on the bacterial count in bioaerosols.

The aerosols generated during dental treatments contain bacteria and other microorganisms that penetrate the body through the respiratory system of dental surgeons and cause infectious diseases. Several studies have been done to reduce these hazards. The aim of the present study is to evaluate the effects of the plant extract essential oil (EO) vapors of Neem, Clove, Cinnamon bark, Thyme, Lemon Grass, and Eucalyptus on the bacterial count in bioaerosols near dental units. Sampling was taken on nutrient blood agar plates by placing them open near dental units using passive air sampling method, before commencement of treatment for 1 h, during treatments for 2 h, and after introducing EO vapors for 2 h. The collected samples were taken for incubation at 37°C for 48 h. The colonies formed were counted in colony-forming units per cubic meter and taken for statistical analysis. After comparing the obtained results, it was found that there was a significant reduction (P < 0.05) in the bacterial count for about 43% near the dental units after the introduction of the EO vapours. It is concluded that natural extracts like EOs can reduce bacterial contamination near dental units in the vapourized state, thereby reducing the health hazards in Dental Health Professionals.

Evaluation of Markers Associated with Physiological and Biochemical Traits during Storage of ‘Nam Dok Mai Si Thong’ Mango Fruits

Mango ‘Nam dok mai si thong’ is in high demand worldwide, displaying desirable attributes which include a particularly sweet flavour and visually appealing appearance. Physiological and biochemical changes that occur in the fruit post-harvest are key factors in determining fruit quality and, consequently, predicted shelf life. In order to understand which post-harvest markers play crucial roles during the ripening process, as well as those which are a consequence of disease infection and physical damage caused by essential oil vapour, partial least squares (PLS) correlation models were used. During storage, physiochemical (percent weight loss, peel colour, firmness, pH, and peel electrolyte leakage) and biochemical (titratable acidity, total soluble solids, total phenolic compounds, total flavonoid compounds, antioxidants, total sugar, and reducing sugar content) parameters, as well as near-infrared (NIR) spectra, were monitored and correlated with visual post-harvest physiological responses. The majority of analysed markers displayed distinct relationships with the ripening process of mangoes, where for non-destructive parameters (R2 = 0.86), lightness (L*) and b* value were notably significant, and for destructive parameters (R2 = 0.79), pH and total soluble solids were notably significant. Similarly, the same markers were also correlated with physical damage and post-harvest mango disease infection severity, possibly through polysaccharide deformation and activation of browning-related enzymes. NIR imaging results also revealed the absorbent regions involved in biochemical alterations (water and enzymes; absorbance at 1170 nm, 1400–1500 nm, and 2150–2250 nm) that pertain to the fruit’s quality. The findings from this work provide an initial step towards the development and assessment of quality measures for ‘Nam dok mai si thong’ mango.