Essential Oil Samples Research Articles

Evaluation of the quality of pomelo (Citrus maxima) essential oil products during storage

The main disadvantage of the pomelo essential oil storage process is the change in colour and composition over time, which significantly affects the quality of essential oils and limits their usability. Thus, this study aimed to determine the effect of packaging type and storage conditions (temperature, time) on the quality of pomelo essential oil products. Pomelo essential oil was preserved in 3 types of packaging (brown glass, white glass, and plastic) at two temperatures of 30°C and 15°C for eight weeks. The parameters used to evaluate the quality of essential oil samples include density, colour index, acid value, chemical compositions, and bioactive activities. The optimal storage conditions of pomelo essential oil were determined as follows: storing in brown glass jars at 30°C for eight weeks. The results showed that after eight weeks, the pomelo essential oil samples were stored in brown glass jars at room temperature (30°C), still retaining their characteristic odour, unchanged colour, density index as 0.856 (g/mL), acid index as 0.748 mg KOH/g, IC50 value as 96.271 (mg/mL), limonene content as 75.99%, indicating that the above storage condition would maintain quality and improve the commercialisation of pomelo essential oil products in the Vietnamese market.

Essential Oils as Antimicrobials against Acinetobacter baumannii: Experimental and Literature Data to Definite Predictive Quantitative Composition-Activity Relationship Models Using Machine Learning Algorithms.

Essential oils (EOs) exhibit a broad spectrum of biological activities; however, their clinical application is hindered by challenges, such as variability in chemical composition and chemical/physical instability. A critical limitation is the lack of chemical consistency across EO samples, which impedes standardization. Despite this, evidence suggests that EOs with differing chemical profiles often display similar (micro)biological activities, raising the possibility of standardizing EOs based on their biological effects rather than their chemical composition. This study explored the relationship between EO chemical composition and antibacterial activity against carbapenem-resistant Acinetobacter baumannii. A dataset comprising 82 EOs with known minimal inhibitory concentration values was compiled using both experimental results and literature data sourced from the AI4EssOil database (https://www.ai4essoil.com). Machine learning classification algorithms including Support Vector Machines, Random Forest, Gradient Boosting, Decision Trees, and K-Nearest Neighbors were employed to generate quantitative composition-activity relationship models. Model performance was assessed using internal and external prediction accuracy metrics with the Matthews correlation coefficient as the primary evaluation metrics. Features importance analysis, based on the Skater methodology, identified key chemical components influencing EO activity. The single chemical components limonene, eucalyptol, alpha-pinene, linalool, beta-caryophyllene, nerol, beta-pinene, neral, and carvacrol were highlighted as critical to biological efficacy. The predictive capacity of the ML models was validated against a test set of freshly extracted and chemically characterized EOs. The models demonstrated a 91% prediction accuracy for new EO samples, and a strong correlation was observed between predicted features importance and experimental inhibitory values for six selected pure compounds (limonene, eucalyptol, alpha-pinene, linalool, carvacrol, and thymol). Additionally, the machine learning approach was extended to cytotoxicity data from 3T3-Swiss fibroblasts for 61 EOs. The analysis revealed the potential to design EOs with both high antibacterial activity and low cytotoxicity through blending or selective enrichment with identified key components. These findings pave the way for biologically standardized EOs, enabling their rational design and optimization for clinical applications.

Comparative qualitative and quantitative analysis of common myrtle and eucalyptus twiggy essential oils

Introduction. In the family Myrtaceae (Myrtaceae L.) there are more than 100 genera and more than 3000 representatives. Insufficiency of data on diagnostics of raw materials of common myrtle and closely related species is an actual problem of modern pharmacognosy. The aim of the present study is a comparative qualitative and quantitative analysis of essential oil components of leaves of common myrtle, closely related to Myrtle species – Eucalyptus twiggy of family Myrtaceae, as well as industrial samples of essential oils of Myrtle and Eucalyptus by gas chromatography-mass spectrometry. Material and methods. Leaves of common myrtle harvested in the Republic of Crimea (Russia) and Relizane province (Algeria) were used as objects of research. Also as objects of comparison were used leaves of eucalyptus twiggy, harvested in Abkhazia, and industrial samples of common myrtle and eucalyptus twiggy essential oils. Samples of essential oil were obtained from leaves of myrtle and eucalyptus. Essential oil samples were obtained from myrtle and eucalyptus leaves and the qualitative and quantitative composition of their components was determined by gas chromatography-mass spectrometry. Results and discussion. Essential oils samples of Myrtaceae representatives leaves are characterised by a high content of mono- and bicyclic monoterpenes, but they differ significantly in dominant components depending on the place of growth. In a sample of essential oil from the leaves of Crimean Myrtle, 1,8-cineol (eucalyptol) dominates, and in a sample from the leaves of Algerian Myrtle, α-pinene dominates. In the study, it was found that some identified components of the common myrtle essential oil, such as myrtenyl acetate, humulene, linalyl acetate, β-myrcene and their derivatives, were absent in the eucalyptus twiggy essential oil, which may serve as a diagnostic sign for Myrtus species. On the contrary, the presence of globulol and its derivatives in the component composition of essential oil was found only in samples of Eucalyptus viminalis L. species and are not determined in the common myrtle essential oil. Industrial samples of essential oils are characterised by the absence of such important components of Myrtle essential oil as α-pinene, globulol, myrtenyl acetate, geraniol, linalool, terpinen-4-ol, humulene and its derivatives. Conclusion. Species specificity of the common myrtle can be confirmed by gas chromatography-mass spectrometry on diagnostically significant components of the common myrtle essential oil, which are absent in the essential oil of the species closely related to myrtle – еucalyptus twig, which can be used in the preparation of the draft pharmacopoeial article on a new type of medicinal plant raw material – ‘Common myrtle leaves’.

Analysis of Volatile Compounds in a Value-Added Jerky by Incorporating Ajwain and Thyme Essential Oils

Ajwain essential oil and thyme essential oil naturally contain important bioactive compounds. Various researchers have discovered that these compounds contribute biological benefits for living things such as humans and animals. Bioactive compounds found in essential oils, such as terpenes and terpenoids, possess antibacterial and flavouring qualities, making them promising natural preservatives in the food business. This study investigates the effect of essential oil treatment methods on their incorporation into dehydrated beef and its subsequent sensory acceptability. The meat samples underwent hot air blanching and oil treatment with doses of 0.75 mL and 1.5 mL, respectively. Subsequently, the samples were dried at 55 °C for 6 h after each treatment. The identification and quantification of volatile chemicals were performed using headspace solid-phase microextraction and gas chromatography–mass spectrometry. Thymol, γ-terpinene, p-cymene, and β-pinene were the predominant compounds before and after the treatments. The findings revealed that the application of ajwain and thyme essential oil treatments resulted in significant differences in the final concentration of monoterpenes. However, the sensory evaluation indicated that the ajwain and thyme essential oil samples received similar overall ratings. Consequently, ajwain essential oil could be a suitable alternative to thyme in beef jerky.

THE EFFECT OF ESSENTIAL OILS ON THE VIABILITY AND ADHESIVE PROPERTIES OF CLINICAL STRAINS OF CANDIDA ALBICANS AND CANDIDA GLABRATA OBTAINED FROM PATIENTS WITH PHARYNGOMYCOSIS

Aim. To investigate the antifungal and anti-adhesive activities of Monarda fistulosa essential oil and cinnamon essential oil on clinical strains of fungi of the genus Candida obtained from patients with pharyngomycosis. Materials and methods. The object of the study was essential oil of Monarda fistulosa and essential oil of cinnamon, the subject of the study was clinical strains of Candida albicans and Candida glabrata isolated from patients with pharyngomycosis. Antifungal effect of essential oils was determined by micromethod of serial dilutions with determination of minimum inhibitory concentration and minimum fungicidal concentration according to the recommendations of International Standards Organisation. The viability of micromycetes was determined by crossing the suspension from the test and control wells on Sabouraud dense nutrient medium with subsequent determination of colony-forming units/ml. Adhesion of Candida fungi was determined according to the method of Brilis V. I. and co-authors. Results. Our studies proved the antifungal effect of essential oil of Monarda fistulosa and essential oil of cinnamon on the studied clinical strains of Candida fungi. The range of subinhibitory concentrations of essential oils that inhibited the viability and adhesive activity of clinical strains of C. albicans and C. glabrata was established. Under the conditions of our experiment, the greatest suppressive ability of subinhibitory concentrations affecting the biological properties of Candida spp. was demonstrated by essential oil of Monarda fistulosa. Conclusions. The antifungal effect of essential oils on clinical strains of micromycetes differed in the strength of effect. The maximum expression of antimycotic effect was demonstrated by the essential oil of Monarda fistulosa. Under the conditions of action of subinhibitory samples of essential oil of Monarda fistulosa and cinnamon essential oil, the viability indices of Candida spp. were significantly lower than those of the culture control, which was not exposed to the action of essential oils. Clinical strains of C. albicans and C. glabratа isolated from patients with pharyngomycosis were characterised by medium-adhesive and low-adhesive activity, respectively. Essential oils in subinhibitory concentrations led to inhibition of the adhesive potential of the studied Candida spp isolates, namely, there was a decrease in the adhesive activity of C. albicans strains from the category of ‘medium-adhesive’ to the category of ‘non-adhesive’ and ‘low-adhesive’, and of C. glabrata isolates – from the category of ‘low-adhesive’ to the category of ‘non-adhesive’.

New insights on the chemical composition and antimicrobial activity of rhizome essential oil from Vietnamese <em>Cyperus stoloniferus</em> Retz. (Cyperaceae)

Cyperus stoloniferus Retz. is a perennial grass-like plant widely distributed in Vietnam. The composition of essential oil isolated from rhizomes has been investigated by a combination of chromatographic (Column chromatography, Gas chromatography in combination with retention indices) and spectroscopic techniques (Mass spectrometry, 13C NMR spectroscopy). Cyperene (15.8%), cyperotundone (12.9%) and α-cyperone (11.2%) were the major components. The composition of essential oil sample from this species in Vietnam differed substantially from that previously reported in China. C. stoloniferus rhizome essential oil displayed weak antibacterial activity against gram-negative bacteria, gram-positive bacteria, and yeasts.

Chemical Composition and Antibacterial Effect of Clove and Thyme Essential Oils on Growth Inhibition and Biofilm Formation of Arcobacter spp. and Other Bacteria.

Background: In recent years, significant resistance of microorganisms to antibiotics has been observed. A biofilm is a structure that significantly aids the survival of the microbial population and also significantly affects its resistance. Methods: Thyme and clove essential oils (EOs) were subjected to chemical analysis using gas chromatography coupled to mass spectrometry (GC-MS) and gas chromatography with a flame ionization detector (GC-FID). Furthermore, the antimicrobial effect of these EOs was tested in both the liquid and vapor phases using the volatilization method. The effect of the EOs on growth parameters was monitored using an RTS-8 bioreactor. However, the effect of the EOs on the biofilm formation of commonly occurring bacteria with pathogenic potential was also monitored, but for less described and yet clinically important strains of Arcobacter spp. Results: In total, 37 and 28 compounds were identified in the thyme and clove EO samples, respectively. The most common were terpenes and also derivatives of phenolic substances. Both EOs exhibited antimicrobial activity in the liquid and/or vapor phase against at least some strains. The determined antimicrobial activity of thyme and clove oil was in the range of 32-1024 µg/mL in the liquid phase and 512-1024 µg/mL in the vapor phase, respectively. The results of the antimicrobial effect are also supported by similar conclusions from monitoring growth curves using the RTS bioreactor. The effect of EOs on biofilm formation differed between strains. Biofilm formation of Pseudomonas aeruginosa was completely suppressed in an environment with a thyme EO concentration of 1024 µg/mL. On the other hand, increased biofilm formation was found, e.g., in an environment of low concentration (1-32 µg/mL). Conclusions: The potential of using natural matrices as antimicrobials or preservatives is evident. The effect of these EOs on biofilm formation, especially Arcobacter strains, is described for the first time.

Study on the ability to inhibit the growth and aflatoxin B1 production from Aspergillus flavus using some essential oils

Vietnam is a country with favorable natural conditions for growing vegetables containing essential oils such as marjoram, dill, lemon basil, perilla, coriander and onions. The objective of this study was to evaluate the inhibition of growth and aflatoxin production in the Aspergillus flavus strain by various essential oils in a culture medium. Samples of marjoram essential oil, dill essential oil, lemon basil essential oil, perilla essential oil, coriander essential oil and onion essential oil were tested for their effects on mycelial growth and aflatoxin production. The findings of this study revealed the antifungal efficacy of all the tested essential oils. The extent of inhibition of fungal growth and aflatoxin production was dependent on the type and concentration of essential oils used. The complete inhibition of A. flavus growth was observed at 1000 ppm concentrations of dill essential oil, lemon basil essential oil, coriander essential oil and onion essential oil. While dill essential oil and lemon basil essential oils showed marked inhibition of aflatoxin B1 produced by A. flavus at all concentrations tested (500, 750 and 1000 ppm).

DETERMINATION OF ANTIMICROBIAL ACTIVITY OF COMMERCIALLY AVAILABLE THYME ESSENTIAL OIL SAMPLES

In this study, the antimicrobial efficacy of four commercial brands of thyme essential oil, sourced from four different vendors (pharmacy, e-commerce, herbalist, and supplier), was evaluated and compared according to their place of purchase. The research utilized standard strains, including Gram-negative bacteria Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853; Gram-positive bacteria Staphylococcus aureus ATCC 29213 and Bacillus cereus ATCC 14579; and fungi Candida albicans ATCC 10231 and Candida tropicalis DSM 11953. Antimicrobial activity was determined using the Minimum Inhibitory Concentration (MIC) method. Among the four brands tested at ten different concentrations on four bacterial and two fungal strains, the thyme essential oil sourced from the pharmacy demonstrated the highest level of antimicrobial activity. Based on our experimental results, the essential oils demonstrated the strongest inhibitory activity against Candida albicans, whereas Staphylococcus aureus exhibited the highest resistance to the tested oils.. All tested concentrations of essential oil samples allowed the growth of S. aureus. These findings indicate that essential oils sold in the market and online, intended for therapeutic purposes, vary significantly in quality. Economic incentives may lead to adulteration of these oils, underscoring the importance of using plant material from the correct species and considering the geographical conditions that influence the plant’s chemical composition. The superior antimicrobial efficacy of the pharmacy-sourced thyme essential oil highlights the need to rely on trained health professionals when selecting products for health-related purposes.

Copper-Cobalt Nanozyme Mimicking Laccase for Sensitive Colorimetric Determination of Cannabidiol in Food and Cosmetics.

In colorimetric analysis, nanozymes are invaluable tools due to their simple production, long-lasting stability, and adaptable enzymatic activity, which enable them to induce changes in substrate color. In this study, a simple nanozyme-based colorimetric sensor was developed to detect cannabidiol (CBD) by using the laccase activity of the self-made MOF with copper and cobalt loading (Cu/Co@MOF) nanozyme, which was synthesized using a one-pot microwave method. The Cu/Co@MOF has the ability to catalyze the coupling reaction between 4-AP and various phenolic substrates, thereby converting colorless phenolic substrates into red substances. Notably, 16 ng/mL was the limit of detection. Based on Y = 0.137X + 0.003 equation, absorbance and CAN concentrations (0.067 to 10 μg/mL with a correlation value [R2] of 0.993) had a significant correlation. The developed colorimetric method was subsequently employed to determine CBD in facial masks and essential oil samples, resulting in relative standard deviations (RSDs) ranging from 1.4% to 4.3%. Therefore, this sensitive, cost-effective, and rapid method ensures an effective determination of CBD in food and cosmetics.

Comparative Studies of Chemical Composition and Biological Activity of Juniperus communis L. Essential Oil From Different Localities in the Republic of Serbia

Abstract This work aims to determine the chemical composition of Juniperus communis (J. communis) essential oil from different localities in the Republic of Serbia and examine its antimicrobial and antioxidative effects together with chemometric analysis and principal component analysis. Essential oils were extracted via hydro distillation from the fruits of J. communis gathered from four different habitats in Serbia. Extraction yields ranged from 1.56 % in the sample from Bavanište to 1.98% in the sample from Mačkat. A total of 23 compounds in the four essential oil samples were identified by Gas Chromatography-Mass Spectrometer (GC-MS). The dominant compounds were α-pinene (32.68–51.10 %), β-phellandrene (6.43–24.77 %), and β-pinene (9.84–14.09 %). Compared with the other ecological factors, precipitation showed a strongly positive correlation (0.871) with essential oil yields. The four samples could be classified into two clusters based on the variance in their components. All the essential oils samples showed bioactivities. Among them, the essential oil from the Mačkat sample showed the best ABTS radical scavenging activity (IC50=237.74 μg/ml), DPPH radical scavenging activity (IC50=308.83 μg/ml) and antimicrobial activities. Consequently, the essential oil extracted from Mačkat has the potential for commercial viability in the food, cosmetic, or medical fields.

Findings on the heavy metal content in herbal drugs and essential oils – An updated database evaluation

In order to guarantee the safety of patients and consumers, the European legal framework restricts the content of heavy metals and further elements in plant material used for the production of medicinal and food products. This data evaluation comprises findings on seven elements between 2016 and 2021 which were assessed against the requirements of the European Pharmacopoeia (Ph.Eur.) and the ICH Q3D guideline on elemental impurities. !5.328 herbal drug samples from 427 products and 537 essential oil samples from 25 products were included in this evaluation which demonstrates that the Ph. Eur. limits set for cadmium, lead and mercury are considered appropriate. Samples from organic production revealed a lower occurrence of cadmium, lead and mercury as compared to samples from conventional production. With regard to the ICH Q3D requirements, none of the herbal drug samples exceeded the respective limit for cobalt, nickel and vanadium, while for arsenic higher values were observed in individual cases. A comparison of the findings with a former period of evaluation showed an increase in positive findings and also a few more exceedances of the Ph.Eur. limits. For essential oils, it can be confirmed that independent from the production process, the probability of heavy metal contamination is low.

Chemical Variability of the Leaf Essential Oil of Two Subspecies of Juniperus oxycedrus L. From Northwestern Algeria.

Thirty-seven essential oil samples have been isolated from leaves of individual plants of Juniperus oxycedrus (subspecies oxycedrus and macrocarpa) growing wild in Tlemcen and Aïn Témouchent provinces (Northwestern Algeria). Analysis of eight selected oil samples by GC(RI), GC/MS and 13C NMR, allowed the identification of 88 components that accounted for 84.4-99.5 % of the whole compositions. The 37 compositions were subjected to statistical analysis which suggested the existence of groups and sub-groups I, IIA and IIB. Group I, the most important group with 24 oil samples out of 37, differed from sub-groups IIA and IIB, essentially by the high content of α-pinene (mean value, 69.2 %; SD 6.24). Sub-groups IIA and IIB were differentiated by their content of α-pinene (Mean values, 49.7 % and 27.3 %, respectively) as well as δ-3-carene (10.3 %, sub-group IIA), sabinene and (Z)-6-pentadecen-2-one (8.7 % and 4.9 %, respectively, sub-group IIB).

Chemical composition, antimicrobial, and anticancer activity of essential oil from Magnolia tiepii sp. nov. leaves

The essential oil isolated by hydro-distillation from Magnolia tiepii leaves was analyzed by GC-MS and assessed for antimicrobial and anticancer activities. Thirty-three components of the essential oil were identified, and the major components were β-pinene (40.8%), β-funebrene (12.0%), and trans-meta-mentha-2,8-diene (8.1%). The oil’s antimicrobial activity was assessed using IC50 values to determine its efficacy against six bacterial strains and one fungus strain. The IC50 values ranged from 2.30 mg/mL to 42 mg/mL, except for C. albicans, whose IC50 did not reach the highest concentration tested (>42 mg/mL). In addition, the anticancer activity of the M. tiepii essential oil was evaluated on KB, HepG2, MCF-7, and A549 cancer cell lines using the MTT method. These cell lines were treated with essential oil samples at concentrations ranging from 0.16 to 42 μg/mL. The M. tiepii essential oil exhibited high anticancer activity, with IC50 values ranging from 0.90 μg/mL to 2.07 ± 0.06 μg/mL across the four tested cell lines. These promising results underscore the potential of M. tiepii essential oil for cancer treatment, offering hope for future research and applications.

Phytochemical variability in essential oils of Juniperus communis var. saxatilis populations grow wild in western Himalaya, India

Needle and berry samples of Juniperus communis L. var. saxatilis Pall. were sampled separately during post rainy season to comparatively investigate the essential oil (EO) yield and phytochemical variability in eight populations grow wild in western Himalaya, India. The EOs obtained from air-dried needle and berry samples separately by hydrodistillation method using Clevenger type apparatus varied in yield with geographic origin of populations, ranged between 2.5-3.4% and 1.8-2.8% (v/w, dried weight basis), respectively. GC-MS analysis of EO profiles resulted in identification of a total ninety-four phytochemicals, representing over 95% of total oil content. Both, needle as well as berry EO samples were dominated by monoterpene hydrocarbons α-pinene (18.52-30.65% and 14.31-27.37%), D-limonene (17.01-28.96% and 15.80-29.70%), β-myrcene (3.74-5.59% and 4.12-14.23%), followed by sesquiterpene hydrocarbons β-elemene (0.86-4.13% and 0.77-3.65%) and germacrene D (0.27-2.57% and 0.20-6.15%), respectively. The oxygenated sesquiterpenes α-cadinol (0.34-5.90% and to 5.63%) and α-bisabolol (to 3.39 and 0.95-6.71%) constituted the third most abundant group of terpenes while oxidized monoterpenes with α-terpineol (0.73-2.17% and 0.10-3.51%) and α-terpinyl acetate (2.10-4.76% and 0.05-3.54%) were the least dominant group. The principal component and hierarchical cluster analysis indicated that selective local environmental forces driving the microhabitat conditions appeared to be linked to high variability in essential oil composition of different common Juniper populations instead of their geographical proximity. The present study revealed that common Juniper essential oils from western Himalaya, India fulfil minimum requirements of European Pharmacopoeia and warrants its further exploitation as a natural resource of commercial significance for dietary and therapeutic applications.

Lavender essential oil market integrity: A comprehensive study of commercial Lavandula angustifolia essential oils adulteration and assessment of industrial standards

Adulteration of essential oils (EOs) is a common and unethical practice that affects both consumers and honest suppliers and harms market integrity. Despite the awareness of this problem, scarce scientific studies are described in the scientific literature. Therefore, 55 samples of lavender EOs were purchased and extensively analyzed to the trace levels, including chromatographic profile, quantitative analysis, and chiral profile. Of the 51 samples labeled as Lavandula angustifolia, 51 % were genuine, 6 % were cheaper lavandin EO, 14 % were fortified with synthetic additives and over 29 % of the samples were adulterated with both lavandin EO and synthetics. Usually, adulterated EOs were cheaper than genuine products, still some expensive products were also falsified. The most common synthetic adulterants were synthetic linalool and linalyl acetate, 3,5,5-trimethylhexyl acetate, α-terpinyl acetate, and dipropylene glycol. Only four of the studied samples were diluted with a medium not fully visible in the recorded GC profile. Industry standards were assessed to eliminate adulterated EOs and ISO 3515 was found to be impractical and too strict, but Ph. Eur. demonstrated its efficiency in eliminating adulterated samples without rejecting many genuine ones.PCA enabled the differentiation of lavender EOs containing synthetics from those of purely natural origin, and in the latter group, to distinguish L. angustifolia from lavandin. Some samples had an unusual composition suggesting that they were artificial blends of synthetics and some terpene fractions of non-lavender origin.This is the first such extensive study of adulteration of lavender EOs, regarding both the number of commercial samples as well as implications on their biological activity. The adulteration via dilution influenced the antimicrobial activity of the essential oils. In conclusion, adulteration is a significant problem in the market, and a large share of products on the market is somehow counterfeited, not only the cheapest products.

Chemometric analysis of fingerprinting derivative spectrophotometry for authentication of shallots

The Bima Brebes, variety of shallots, was in high demand, which led to mixing with other varieties. Derivative spectrophotometric fingerprinting combined with chemometrics was used to distinguish between authentic and adulterated shallot varieties. The objective of this study was to identify the original spectra and their derivative spectrophotometric fingerprinting, as well as classify and differentiate between shallot varieties using chemometrics. UV-Visible (UV-Vis) spectrophotometry was used to test essential oil samples from three shallot varieties and their mixtures, followed by spectral derivatization. The spectral data revealed distinct patterns for each sample, including individual varieties and mixtures, and was then analyzed using Principal Component Analysis (PCA) and Partial Least Square-Discriminant Analysis (PLS-DA). The original spectra and their derivatives showed similarities across the samples. PCA and PLS-DA results indicated that the second-order derivative data provided the greatest separation, with a total Principal Component 1 (PC1) and Principal Component 2 (PC2) value of 62.2%, a total component 1 and 2 value of 60.1%, and the highest Variable Importance in the Projection (VIP) score wavelength of 225 nm. The PLS-DA results were validated to ensure that the model was not overfit, as evidenced by a satisfactory cross-validation quality (Q2/R2) value of 0.693 and a significant permutation test. The combination of derivative spectrophotometry fingerprinting and a chemometric approach effectively classified different samples, allowing for the determination of the authenticity of a specific shallot variety.

Essential Oil and Waste Hydrosol of Ocimum Tenuiflorum L.: A Low-Cost Raw Material Source of Eugenol, Botanical Pesticides, and Therapeutic Potentiality.

In this study, essential oils and waste hydrosols of leaves of Ocimum tenuiflorum in four different geographical locations were extracted by hydrodistillation method and using gas chromatography/mass spectrometry (GC/MS) for chemical composition analysis. All four essential oil samples contained the main components (E)-β-caryophyllene (27.8-49.0 %), trans-β-elemene (20.3-37.1 %) and eugenol (9.0-44.0 %). Three of the four hydrosol samples had eugenol in absolute content (94.5-98.6 %), while the remaining hydrosol sample had two main components, elemicin (77.8 %) and eugenol (14.2 %). Essential oils and hydrosols demonstrated larvicidal activities against four important disease-transmitting mosquito species including Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Culex fuscocephala with 24-h LC50 values in the range 15.42-56.01 μg/mL and 53.88-97.80 μg/mL for the essential oils and the hydrosols, respectively. Essential oils and hydrosols strongly inhibited the acetylcholinesterase (AChE) enzyme of electric eels with IC50 values in the range of 25.35-107.19 μg/mL. Microemulsion (ME) can be considered as a sustainable pesticide formulation over 300 days and has improved larvicidal activity compared to free essential oil. The O. tenuiflorum in Vietnam can be considered a low-cost source of eugenol, botanical pesticides that control disease-transmitting mosquitoes, as well as having therapeutic potential to be further investigated.

Employment of MQ gas sensors for the classification of Cistus ladanifer essential oils

The chemical composition of essential oils (EOs) from Cistus ladanifer has a huge variability throughout the year, impacting the oil quality. Nowadays, EO analytic chemistry techniques, which are expensive and destroy the sample, are utilized to measure the chemical composition. In the paper, we propose a combination of low-cost sensors and machine learning based system. As low-cost sensors, seven gas sensors are combined to obtain up to 36 features. Regarding machine learning, 31 multiclass classification algorithms are applied. Data from sensors were collected for 33 samples of EO from Cistus ladanifer. The generated dataset was split into training and test datasets, with 75 % of the data for training. The datasets were created to ensure a homogeneous chemical composition distribution on both training and test datasets. There were three target chemical compounds: Alpha-pinene and Viridiflorol as individual compounds and Terpenic Hydrocarbons as a group of chemical compounds. The value of the percentage of each targeted compound is converted into a categoric variable with 5 possible values, 1 being the lowest concentration and 5 being the maximum one. The data of the MQ-sensors were included as the input for the models, and each one of the targeted chemical compounds was selected as an output for different models. The input features were ranged using different algorithms for the feature selection process. The results indicate that there is no valid classification model for Viridiflorol, and limited accuracy is achieved for Alpha-pinene. Meanwhile, for Terpenic Hydrocarbons, an accuracy of 91.6 % is achieved. It is important to highlight that these accuracies were attained when a reduced number of features were included, ranging the number of features from 11 to 13. This is the first case in which MQ-based gas sensors, or other metal oxide sensors, are used to correctly determine the concentration of a chemical compounds in a complex matrix formed by dozens of compounds. This system will provide a cheap method to determine the quality of EOs and confirm the benefits of combining low-cost sensors with machine learning.

Extraction of Origanum onites L. using an industrial-type microwave-assisted distillation (MWAD) system: Increasing energy saving and essential oil yield compared to conventional steam distillation

Oregano species are commonly utilized for different medical purposes as well as for other essential oil products. One of the oregano species, Origanum onites L. has a dense natural distribution in the Aegean and Mediterranean regions of Turkey and Greece and is cultivated mainly in Denizli province. Turkey meets 80 % of the world's oregano market. Since Origanum onites L., whose essential oils are of high quality, has a high economic value, assessing the quality and production of essential oils extracted using various methods is important. Microwave-assisted distillation (MWAD) processes are generally carried out under laboratory conditions using clevenger or small-scale specialized instruments made for research in the lab. Thus, designing industrial-scale distillation systems with microwave power is necessary. For this reason, an industrial-type MWAD system with 12 magnetrons (power output of 1 kW) was developed in this work, and both conventional steam distillation (SD) and MWAD of oregano plant were realized, as a novelty. This study experimentally investigated the effects of microwave power and applied time on both energy saving (%) and essential oil yield (%). System was designed to distill 9 kg of dried plants chopped at once and the results obtained were used to obtain reference data for MWAD systems that can be used in industrial systems. The obtained essential oil samples were subjected to GC-MS analysis for chemical analysis. A statistical analysis of the experimental data was performed via Design Expert software to elucidate the impact of microwave power and time on essential oil yield and energy savings. When the results were evaluated, the essential oil yield of oregano plant increased by 4–22 % with the MWAD system compared to SD. The highest increase in yield was achieved with the test (500 W + 40 min). Also, the distillation time with MWAD system was 50 % shorter than with SD system. The MWAD system consumed at least 25 % less energy. According to the GC-MS analysis results, carvacrol increased steadily depending on the time applied microwave power as well as oxygenated monoterpenes. The chemical composition of the essential oils obtained from the proposed MWAD system did not show any incompatible value according to the ISO-7925 standard. As a result, this proposed method can be safely used in industrial systems.