Spice Essential Oils Research Articles

Recent advances in the preservation effects of spice essential oils on fruits and vegetables

Spice essential oils (SEOs) are currently a prominent area of investigation in food preservation due to their natural, effective, and environmentally friendly properties. This review discussed the latest research progress concerning the application of SEO in fruits and vegetables preservation. The article commenced with an overview of the sources of SEOs and their main components, explored their bioactivities, antimicrobial mechanisms, and the microencapsulation and nanotechnology utilizing spice essential oils. Further research explored the applications of SEOs in culinary, pharmaceuticals, cosmetics, agriculture, and food industries, with a focus on evaluating their effectiveness in extending the shelf-life of fruits and vegetables. Additionally, it discusses limitations such as intense aroma and toxicity concerns, while also outlining prospects for future research and applications in the food sector. Overall, SEOs offer promising avenues for effectively prolonging the storage period of post-harvested fruits and vegetables while maintaining their quality attributes.

The synergistic antimicrobial effects and mechanism of cinnamon essential oil and high voltage electrostatic field and their application in minced pork

Spice essential oils (EOs) have potent antimicrobial ability, but their application as food preservatives was severely limited by strong sensory properties. In this study, high voltage electrostatic field (HVEF) was applied to strengthen the antimicrobial effect of EOs while reducing their additive dosage. First, cinnamon essential oil (CEO) was selected from ten spice EOs because of its strongest inhibition against bacteria (Escherichia coli and Staphylococcus aureus) and molds (Penicillium citrinum and Aspergillus niger) common in foods. Then, the antimicrobial effect and mechanism of CEO and HVEF used alone or in combination were investigated. The results exhibited that the antimicrobial effect of CEO was dramatically enhanced by combining with HVEF, as the required concentration for the same antimicrobial effect was only 1/4∼1/3 of that when used alone. Both CEO and HVEF treatments changed the permeability of the microbial cell wall as well as the permeability and integrity of the cell membrane, resulted in the change in membrane protein structure, led to the increase in content of reactive oxygen species in the microbial cells, while the combined treatment of HVEF and CEO (HVEF + CEO) caused the significantly greater effect on microbes than two treatments applied alone. Finally, HVEF was found to substantially improve the preservative effect of CEO, allowing CEO to prolong the shelf life of minced pork from about 3 d to 7 d without compromising its original sensory quality.

A novel aspect on different preservation methods for tomato paste by examining the protective effect of herb and spice oils.

In this study, the effect of essential oils of herbs and spices on the protection of homemade tomato paste without additives was investigated. Garlic oil was used as plant essential oil and thyme oil was used as spice essential oil. Samples were kept without adding essential oils at the specified holding times in determined light and dark ambient conditions. After the test period of the prepared setups was completed, the amount of mold formed in the tomato paste was observed, and the optimum samples were determined as K4A4, K4K7, K4K13, K6K10, S6K4, S6K7, S6K10, S6A13 by weighing again and creating a %-time graph by mass. It was decided that thyme essential oil had a more protective effect in foods than garlic essential oil, with the analysis methods performed on optimum samples (Physical analysis, microbiological analysis, FT-IR, and TG DTA).

Growth Inhibition of Phytopathogenic Penicillium Citrinum and Penicillium Expansum by Some Indian Culinary Spices

Penicillium citrinum and Penicillium expansum are primarily associated with the spoilage of wide variety of fruits and derived food products. Increasing demand of consumers for preservative (synthetic) free food has led the researchers to explore natural substances for controlling spoilage and pathogenic microbes. Past researches have demonstrated the antimicrobial activities of spices. Present study was undertaken to assess the growth inhibitory activities of aqueous extracts (AEs), essential oils (EOs) and powdered (PD) forms of 10 spices towards P. citrinum (MTCC2553) and P. expansum (MTCC2006). PD spices were evaluated for their growth inhibitory potential using spice agar method. Impregnated paper disc method was followed for the antifungal screening of AEs and EOs, while broth dilution method was opted for the determination of their minimum inhibitory concentrations. Results revealed that AEs of all the spices were found ineffective, whereas PD forms of three spices, namely, Cinnamomum cassia (Blume), Cuminum cyminum and Syzygium aromaticum, significantly arrested the growth of both the fungal strains. Nevertheless, EOs of Allium sativum, Brassica juncea, C. cassia (Blume), C. cyminum, Mentha piperita, Ocimum sanctum and S. aromaticum, exhibited remarkable antifungal activities against both the fungi. P. citrinum was more susceptible as compared to P. expansum, towards tested substances. According to our results, PD spices, being cheap and safe, may be persued as ‘green antimicrobials’ along with spice EOs, for in vivo studies to extend the shelf life of fruits and their processed products. Therefore, this study would prove a great help to the agricultural sector and food processing industry.

Tea tree (Melaleuca alternifolia) Essential Oil Concentration in Microemulsion with Antibacterial and Antifungal Activity: An Overview

Abstract: The tea tree (Melaleuca alternifolia), a member of the Myrtaceae family, is a valuable medicinal and aromatic plant. Tea Tree essential oil (TTO) has many medical applications, including antibacterial, antifungal, antiviral, antiprotozoal, anti-inflammatory, antioxidant, and anticancer properties. Although the concentration of TTO in a microemulsion is of economic interest, very few studies on this product have been conducted. In this study, we look at how different tea tree oil concentrations in microemulsion formulations affect susceptibility to various bacteria and fungi. TTO susceptibility in a diverse range of microbial species has now been studied using data from a previously published literature review survey. Most bacteria are resistant to TTO at concentrations as low as 1.0 percent, but mucosal skin staphylococci and micrococci, Enterococcus faecalis, and Pseudomonas aeruginosa have minimum inhibitory concentrations much higher than 2 percent. TTO susceptibility in fungi has only recently been scrutinized. Fungicidal dosages range from 0.12 to 2 percent, with minimum inhibitory concentrations ranging from 0.03 to 0.5 percent and the only notable exception is Aspergillus niger, which contains fungicidal concentrations of up to 8%. The review emphasizes the importance of new antibacterial and antifungal formulations, as well as the role of natural essential oils in the discovery of new antibacterial and antifungal agents, and discusses, in brief, all constituents derived from the essential oil (tea tree) that are in preclinical and clinical development. This paper summarizes human and food-borne bacteria and fungi susceptibility to tea tree essential oils and their constituents. Among the many tested, essential oils of spices and herbs (Melaleuca alternifolia) were found to have the strongest antimicrobial properties. This review looks at a wide range of scientific literature, including Sci-hub, Google Scholar, Pub, Chem, NCBI, and web books.

Development of quinoa (Chenopodium quinoa Willd) protein isolate-gum Arabic conjugates via ultrasound-assisted wet heating for spice essential oils emulsification: Effects on water solubility, bioactivity, and sensory stimulation

Quinoa protein isolate-gum Arabic (QPI-GA) conjugates were developed by ultrasound-assisted wet heating to improve the water solubility and bioactivity of spice essential oils (EOs) in this study. The optimal conditions for QPI-GA conjugates preparation were found to be: heating temperature of 72 ℃, ultrasound power of 450 W, and reaction time of 46 min. QPI-GA conjugates displayed significantly higher emulsifying efficiency and stronger tolerance to pH variation, high salt concentration, and storage than raw materials. The emulsifying efficiency of emulsions was also influenced by the pH and viscosity of EOs, zeta potential of the emulsion as well as the relative density and lipid/water partition coefficient (P) of EOs were the possible factors impacting the stability of EO emulsions. The water solubility, antioxidant ability, and antibacterial ability of tested EOs were improved after emulsification. Meanwhile, encapsulation with QPI-GA conjugates played a good effect on reducing the sensory stimulation of EOs.

Chemistry behind quality – The usability of herbs and spices essential oils analysis in light of sensory studies

The common protocols for the quality determination of medicinal and aromatic plants (MAPs), including herbs and spices (HSs), are the yield and composition of essential oils (EOs). Meanwhile, studies on the sensory quality of HSs showed that EOs composition does not translate to the profile of volatiles emitted from plants; therefore, they do not provide a background for sensory quality assessment. Thus, in this study, the differences in the composition of the EOs and the patterns of emission of unlimited (pure EOs) or limited (presence of a plant matrix) volatiles by headspace were measured for three chemotypes of mint, namely menthol, carvone, and linalool ones. The results have demonstrated that the presence of a plant matrix may change the contribution of main volatiles even up to 47 percentage points, what allows suggesting that EOs chemical analysis is not a reliable method for the determination of sensory quality of HSs.

Influence of Seasonings and Spice Essential Oils on Acrylamide Production in a Low Moisture Model System.

Acrylamide (AA) is a typical contaminant produced during the heating process. In the present study, two seasonings (soy sauce and rice vinegar) and three spice essential oils (chive, ginger, and pepper) were added to the asparagine (Asn)/glucose (Glc) diethylene glycol model system to investigate the production of AA in a low moisture model system. The generation of AA was significantly enhanced when low levels of soy sauce (1% and 3% v/v) were added (p < 0.05). The Asn/Glc model system was heated for 15 min with 0%, 1%, or 3% (v/v) soy sauce, containing 43 mg/L, 63 mg/L, and 53 mg/L AA, respectively. However, the addition of a high level of soy sauce (5% v/v) showed significant inhibition of AA production after heating for 10 min (p < 0.05). About 36% of AA was inhibited in the Asn/Glc/soy sauce (5%) model system after heating for 15 min. The addition of low levels of rice vinegar (1% and 3% v/v) showed comprehensive effects on AA production. Nevertheless, the addition of rice vinegar at 5% v/v had an inhibitory effect on AA generation (p < 0.05). All kinds of spice essential oils promoted the production of AA (p < 0.05). There was a dose−response relationship between the level of spice essential oils and the generation of AA. This study proposes the importance of seasonings and spice essential oils for AA production in food preparation.

Encapsulation of different spice essential oils in quinoa protein isolate-gum Arabic coacervates for improved stability

A fully plant-based wall material, quinoa protein isolate-gum Arabic (QPI-GA) complex coacervate, was developed for stability improvement of different spice essential oils (EOs): Sichuan pepper EO (SPEO), ginger EO (GEO), and star anise EO (SAEO). The optimum pH and QPI-to-GA ratio to form QPI-GA coacervates were experimentally confirmed to be 3.6 and 4:1. IF, FTIR, and XRD analyses (shown in supplementary information) indicated that complex coacervation generated electrostatic interactions between QPI and GA molecules and caused a more ordered structure of QPI-GA coacervates. The QPI-GA coacervates exhibited high encapsulation efficiency for SPEO (82.53 ± 1.59 %), GEO (88.19 ± 2.37 %), and SAEO (84.68 ± 1.51 %). The encapsulated EOs showed substantially higher stability in comparison to free EOs, while some differences in each type of stability among encapsulated EOs were observed. Additionally, the QPI-GA coacervate wall materials made EOs stable in oral and gastric stages and sustainably release in intestinal stage, which contributed to the excellent absorption of EOs in simulated digestion.

Annual Report 2022 of Current Applied Science and Technology

In the year 2022, the journal published 90 articles in Vol. 22 Nos. 1-6. There are 9 articles from KMITL, 31 articles from outside KMITL and 50 articles from overseas. Comparison of manuscripts submitted for publication in 2019, 2020 and 2021 are shown in Figure 1. The number of manuscripts submitted increased from 244 in the year 2020 to 374 and 382 articles in the year 2021 and 2022, respectively while the acceptance rates in 2020-2022 are 27.89%, 15.95% and 10.84%. The top ten countries of authors submitting manuscripts to be published in the journal in 2022 are shown in Figure 2, where Thailand (28.43%), India (19.44%) and Indonesia (12.58%) are among the top three countries. Figure 3 shows the average duration process for publication during 2020-2022. The average duration processes from received to accepted dates are 110.91, 162.98 and 199.82 days in 2020, 2021, 2022, respectively. Due to the change of the submission system in 2021 and 2022, average duration process was much longer than in 2020. The subject area and category of published articles in 2022 according to SJR are in 3 categories: 1) Agricultural and Biological Sciences (Agricultural and Biological Sciences (miscellaneous) and Agronomy and Crop Science), 2) Biochemistry, Genetics and Molecular Biology (Biotechnology) and 3) Environmental Science (Environmental Engineering). Scopus cite score and SCImago journal rank of the journal in 2020-2022 are shown in Figure 4. The cite score increased from 0.3 in 2020 to 1.1 in 2022 (last update on 6 Dec 2020). However, SCImago journal rank in 2022 has not been reported yet. In addition, the most cited article in Scopus is “Chicken Feathers Based Keratin Extraction Process Data Analysis Using Response Surface-Box-Behnken Design Method and Characterization of Keratin product” published in 2020 followed by “Characterization, Functionality and Antioxidant Activity of Water-Soluble Proteins Extracted from Bombyx Mori Linn.” published in 2018 and “Antimicrobial Activity of Edible Electrospun Chitosan/Cellulose Acetate/Gelatin Hybrid Nanofiber Mats incorporating Eugenol” published in 2019. The most cited article in TCI is “Antibacterial Activity of Crude Ethanolic Extracts and Essential Oils of Spices Against Salmonellae and Other Enterobacteria” published in 2005 followed by “Preparation of Red Yeast Rice Using Various Thai Glutinnous and Monascus purpureus CMU001 Isolated from Commercial Chinese Red Yeast Rice Sample” published in 2007 and “Importance of Aflatoxins” published in 2002.

Recent Advances in the Extraction of Spice Essential Oil and Oleoresin: A Review

Essential oils and oleoresins are the secondary metabolites of spice origin and have wide application in the food industry because of their flavour and aroma. They are recovered by various extraction techniques. Both conventional and emerging techniques are being utilized for this purpose. Conventional methods of spice extraction include, distillation and solvent extraction. Continued search for better extraction techniques finally ended up in the development of various advanced technologies. Methods such as supercritical fluid extraction, microwave assisted extraction, enzyme assisted extraction and ultrasound assisted extractions fall under emerging extraction techniques. These advanced technologies helped to solve the limitations in conventional methods. Selection of extraction technique depends on the requirement and economic feasibility. This review deals with the emerging techniques involved in the extraction of essential oils and oleoresins.

Chemical Composition, Antifungal and Antioxidant Activity of Some Spice Essential Oils

This study was carried out to determine the chemical composition of some spice essential oils, to test the radical scavenging and the anti-fungal activities of Cinnamon, Anise, Cumin and Caraway EOs. The essential oil compositions were determined by GC-MS and showed variation in its constituent for each type of oil. Major identified components were Cinnamaldehyde 81.79 % for Cinnamon EO (Ci-EO), Anethole 90.9% for Anise EO ( An-EO), (gamma-Terpinene 23.84%, beta.- Pinene 21.84%, Benzaldehyde, 4-(1-methylethyl) 20.00%, Carenal 17.50% and Benzene, 1-methyl-3-(1-methylethyl) 14.10%) for Cumin EO ( Cu-EO ) and (Carvone 52.27% and D-Limonene 47.13 %) for Caraway EO (Ca-EO). Antioxidant effectiveness was examined by the 2,2'-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method using different concentrations of EOs (2.5, 5.0, 10.0 , 20.0 , 40.0 , mg/ml) at different times. All essential oils have shown antioxidant activity. Based on their antioxidant capacity, four spice essential oils sorted in descending order: Cumin 87.4% &gt; Anise 72.4% &gt; Caraway 59.5 &gt; Cinnamon18.2 % at high concentration 40.0, mg/ml at 120 min. These essential oils were also found to possess remarkable antifungal activity against tested pathogens like yeasts (Candida krusei ATCC 6258, Candida parapsilosis ATCC 22019) and fungi (Aspergillus niger, Aspergillus flavus and Aspergillus fumigatus) by using disc diffusion technique. Cu- EO showed 100% inhibition against A. niger, C. krusei and C. parapsilosis. For other tested fungi, the essential oils showed good to moderate inhibitory effects. Positive and important associations between mycelial growth inhibition of both pathogens and the antioxidant activity of the checked oils. These results showed tested essential oils could be used as a source of antioxidant and antifungal compounds which may find applications in pharmaceutical and food industries.

Elucidation of aroma compounds in passion fruit (Passiflora alata Ait) using a molecular sensory approach.

In this experiment, Guangxi passion fruit was used as the raw material for natural aroma extraction using the spinning cone column (Spinning Cone Column, SCC) technique. In combination with the semi-quantitative method, the aroma characteristics of the raw pulp (raw whole-fruit puree, PU) before SCC processing, residue (Residue, RS) and extract (Extract, EX) after SCC processing, and passion fruit juice (Juice, JU) were evaluated for their aroma characteristics using headspace gas chromatography-mass spectrometry (HS-SPME-GC-MS), gas chromatography-ion mobility spectrometry (GC-IMS), electronic nose, and sensory evaluation. As a result, a total of 110 aroma substances were detected in four samples, and 33, 38, 73, and 28 aroma components were detected from PU, RS, EX, and JU, respectively. There are 50 compounds in EX with concentrations greater than 10 μg/kg, and 19 of them had OAV values greater than 1, including β-Ionone and linalool, which contributed significantly to the aroma. The aroma profiles and characteristics were further analyzed for JU and EX using the e-nose sensor, and it was found that both showed similar aroma profiles. The sensory evaluation results were also in general agreement with the results obtained from the electronic nose, with EX having mainly "floral", "fruity," and "sweet" aromas. The results demonstrated that the spinning cone column technique can increase the fresh and natural fruity aroma of passion fruit in the extract, which has the effect of enriching the aroma and improving the aftertaste. This study will make a foundation for passion fruit SCC extract application in drinks. PRACTICAL APPLICATIONS: Compared with traditional extraction technology, spinning cone column technology has the advantages of high mass transfer efficiency, short extraction time, a wide range of temperature control, and the most complete extracted flavor substances, which greatly reduces the damage degree of heat-sensitive flavor substances and condense aroma. It is widely used in beverages, wine, dairy products, fruit and vegetable, spice essential oil, and other industries. Passion fruit flavor prepared by SCC technology has the advantages of high purity and high concentration, which can be used in solid drinks, baked food, convenience food, tobacco, perfume, and other products. Besides, GC-IMS is an efficient and rapid new analytical technique, which has been widely used in the flavor analysis of volatile organic compounds in food and traditional Chinese medicine samples.

APPLICATION OF GINGER ESSENTIAL OIL IN THE FOOD SECTOR

&#x0D; This study aims to determine the usage of spice essential oils, specifically ginger, in the food sector. This study is a literature study. The source of the article writing library were taken from Google Scholar and www.scimagojr.com with relevant study. According to the findings, essential spice oils, especially ginger, can be used as seasonings in the food sector which can extend the shelf life and enhance the taste of a product. This is supported by the chemical nature of ginger essential oil, which contains compounds. Therefore, food additives can be added to the food manufacturing process. Since the main principle of adding food additives is to prevent the growth, oxidation and unwanted chemical changes of bacteria, so that food looks good as well as its tastes, hence food can be consumed safely.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D; &#x0D; Keywords: Ginger Essential Oil, Food Sector, Shelf Life&#x0D;

Research Note: Preservative effect of compound spices extracts on marinated chicken

The antimicrobial effect of 21 nature spices essential oils (EOs) on marinated chicken was investigated and response surface analysis was applied to obtain the optimal combination. Cassia bark EO, cinnamon EO, tea tree EO, and angelica EO had the best antibacterial effect. Their inhibition zone diameters (IZD) were 23 mm, 21 mm, 15 mm, and 12 mm, and their minimal bactericidal concentrations (MBC) were 1.25 μL/mL, 1.25 μL/mL, 10.00 μL/mL, 20.00 μL/mL. Using the Box-Behnken Design model, with the minimum total number of spoilage bacteria as the evaluation index, the optimal mixture was cassia bark EO 2.40 μL/mL, cinnamon EO 1.00 μL/mL, tea tree EO 3.50 μL/mL, and angelica EO 9.00 μL/mL. Compared with the control group, the total number of colonies was reduced by 1.3 log unites at the 12th sampling day, and the protein degradation process was slowed down owing to the preservative addition. These results indicate the potential application of nature extracts in chicken and other meat preservation.

Development of Antibacterial Biocomposites Based on Poly(lactic acid) with Spice Essential Oil (Pimpinella anisum) for Food Applications.

Among the main biodegradable food packaging materials, poly-lactic acid (PLA) is a commercially successful polymer used notably in the food packaging industry. In this study, active PLA films containing different percentage of anise essential oil (AE) (0, 0.5, 1 and 1.5% v/v) were developed, and characterized by physical, mechanical and antibacterial analysis. Based on physical examinations, thermal stability of PLA/AE films was greater than the neat PLA film, and the minimum water vapor permeability (WVP) was recorded for PLA/0.5AE film (1.29 × 10−11 g/m s Pa), while maximum WVP was observed for PLA/1.5AE (2.09 × 10−11 g/m s Pa). Moreover, the lightness and yellowness of the composites were decreased by the addition of AE. For the PLA composites with 1.5% AE, the tensile strength decreased by 35% and the elongation break increased by 28.09%, comparing to the pure PLA. According to the antibacterial analysis, the minimum inhibitory concentrations of PLA/AE film were 5 to 100 mg/mL and the active composite could create visible inhibition zones of 14.2 to 19.2 mm. Furthermore, the films containing AE inhibited L. monocytogenes and V. parahaemolyticus in a concentration-dependent manner. The confirmation of the success of the incorporation of EOs into the PLA films was further evaluated using principal component analysis, where positive results were obtained. In this context, our findings suggest the significant potency of AE to be used as an antibacterial agent in active food packaging.

Antiaflatoxigenic potential of essential oils of spices – a review

Mycotoxins are important food contaminants posing a significant threat to food and feed safety and public health. Among the mycotoxins, aflatoxins are deemed to be a more significant contaminant due to their potent carcinogenic, and hepatotoxic effects, and their levels are highly regulated in the international food trade. Phytochemicals are considered a major source of natural antifungal agents. The volatile nature of essential oil of plants makes them ideal candidates for antifungal agents due to their ability to distribute in free air spaces in closed containers and penetrate through heterogeneous food materials. In these, essential oils in spices attain special attention due to their commercial availability and low toxicity. This article reviews the antiaflatoxigenic capacity of spice essential oils and the effect of essential oil composition on the activity and mechanism of antifungal action and is expected to be useful for the planning of further research in the subject area.

Inhibitory effect of some spice essential oils on growth of some gram‐negative and gram‐positive bacteria and a yeast

Disk diffusion method to determine antimicrobial activity of plant essential oils was used. While the essential oil extracted from oregano has a high effect on nine of our test microorganisms (75%), one of them had a medium effect and two of them had a weak effect in the test results. While the essential oil obtained from thyme was effective on VRE, MSSA, Escherichia feacalis, and Staphylococcus epidermidis, it was not effective on Salmonella enteritidis, Pseudomonas aeruginosa, and Candida albicans. The most effective essential oils on microorganisms were oregano, thyme, and lavandula oils. The essential oils were more effective to MSSA, VRE, E. feacalis, and S. epidermidis. In our study, we aimed to shed light on the beneficial use of herbal products for human health. The pandemic process has shown the importance of fight against pathogenic microorganisms. We believe that this study will contribute to conservation medicine. Practical applications In recent years, plant products such as exytract, essential, oleoresin oil, etc. have become crucial due to the rapid resistance microorganisms have built to antibiotics. Essential oils have been generally used in cosmetics, medicine, and food industries. Also, the volatile compounds obtained from plants have antimicrobial, antifungal, and insecticidal effects. The antimicrobial activity of essential oil is fundamentally attributed to its main components, but the synergistic or antagonistic effect of a compound in the small percentage of the mixture must be taken into consideration.

Bioactivity of Different Chemotypes of Oregano Essential Oil against the Blowfly Calliphora vomitoria Vector of Foodborne Pathogens.

Simple SummaryCalliphora vomitoria L. is a very common synanthropic blowfly. Since it is attracted by human food, it plays a main role in the transmission of foodborne diseases. Among aromatic plant essential oils (EOs), those of spices are the most suitable to protect food from insect pests. In the present work, we determined the bioactivity of three oregano EOs against C. vomitoria. The chemical analyses showed that the EOs belonged to three chemotypes, one with a prevalence of carvacrol and two with a prevalence of thymol. The bioassays showed that the bioactivity of the EOs significantly varies among chemotypes, with the thymol chemotype showing an overall higher efficacy compared to the carvacrol one.Blowflies play a substantial role as vectors of microorganisms, including human pathogens. The control of these insect pests is an important aspect of the prevention of foodborne diseases, which represent a significant public health threat worldwide. Among aromatic plants, spices essential oils (EOs) are the most suitable to protect food from insect pests. In this study, we determined the chemical composition of three oregano EOs and assessed their toxicity and deterrence to oviposition against the blowfly Calliphora vomitoria L. The chemical analyses showed that the EOs belonged to three chemotypes: one with a prevalence of carvacrol, the carvacrol chemotype (CC; carvacrol, 81.5%), and two with a prevalence of thymol, the thymol/p-cymene and thymol/γ-terpinene chemotypes (TCC and TTC; thymol, 43.8, and 36.7%, respectively). The bioassays showed that although all the three EOs chemotypes are able to exert a toxic activity against C. vomitoria adults (LD50 from 0.14 to 0.31 μL insect−1) and eggs (LC50 from 0.008 to 0.038 μL cm−2) as well as deter the oviposition (Oviposition Activity Index, OAI, from 0.40 ± 0.04 to 0.87 ± 0.02), the bioactivity of oregano EOs significantly varies among the chemotypes, with the thymol-rich EOs (TCC and TTC) overall demonstrating more effectiveness than the carvacrol-rich (CC) EO.

Chemical composition, antibiofilm activities of Tunisian spices essential oils and combinatorial effect against Staphylococcus epidermidis biofilm

This study describes the chemical composition, the antibacterial and antibiofilm activities of essential oils (EOs) from Piper nigrum (Pn.EO), Cuminum cyminum (Cc.EO), Curcuma longa (Cl.EO) and Cinnamomum verum (Cv.EO) frequently used in Tunisian cuisine. The chemical composition analyses evaluated by GC-MS showed high contents of Eugenol (57.87%) in Cv.EO. While, Cl.EO contained β-Turmerone (43.98%) and α-Curcumene (30.34%) as major constituents. The main component of Cc.EO was Cuminaldehyde (28.22%), whereas Pn.EO was mainly characterized by the abundance of Limonene (19.99%), β-Caryophyllene (16.8%), α-Pinene (15.88%), δ-3-Carene (13.05%) and β-Pinene (12.74%) as main components. Our results revealed two different groups of the present studied EOs. The first group combined the Pn.EO and Cc.EO, while the second combined the two other essential oils Cl.EO and Cv.EO. Cv.EO showed the strongest antibacterial activity against the majority of tested strains. The anti-adherence and eradication activities of EOs were tested against Staphylococcus epidermidis biofilm. The highest anti-adherence effect was observed for Cv.EO, which inhibited the biofilm formation even at low concentrations (0.78 μL/mL). Results point to the possibility of using Cv.EO as food preservatives in the traditional preparations and in the food industry.