Thymus Capitatus Essential Oil Research Articles

In vitro and in vivo anthelmintic effect of essential oil obtained from Thymus capitatus flowers against Haemonchus contortus and Heligmosomoides polygyrus

Sheep haemonchosis is a disease that causes serious losses in livestock production, particularly with the increase of cases of anthelmintic resistance around the world. This justifies the urgent need of alternative solutions. The aim of this study was to determine the chemical profile, in vitro, and, in vivo, anthelmintic properties of Thymus capitatus essential oil. To evaluate the, in vitro, anthelmintic activity of the T. capitatus EO on Haemonchus contortus, two tests were used: egg hatch assay (EHA) and adult worm motility (AWM) assay. The nematicidal effect of this oil was evaluated, in vivo, in mice infected artificially with Heligmosomoides polygyrus using faecal egg count reduction (FECR) and total worm count reduction (TWCR). Chromatographic characterization of T.capitatus composition using gas chromatography coupled to mass spectrometry (GC-MS) demonstrated the presence of carvacrol (81.16%), as the major constituents. The IC50 values obtained was 1.9 mg/mL in the EHT. In the AWM assay; T. capitatus essential oil achieved 70.8% inhibition at 1 mg/mL after 8 h incubation. The in vivo, evaluation on H. polygyrus revealed a significant nematicidal effect 7 days post-treatment by inducing 49.5% FECR and 64.5% TWCR, using the highest dose (1600 mg/kg). The results of present study, demonstrate that T.capitatus EO possess a significant anthelmintic properties. Furthermore, it could be an alternative source of anthelmintic agents against gastrointestinal infections caused by H. contortus.

Antibacterial Effect of Eight Essential Oils against Bacteria Implicated in Bovine Mastitis and Characterization of Primary Action Mode of Thymus capitatus Essential Oil.

During the current investigation, eight essential oils (EOs) were tested for their antimicrobial activity against six species, belonging to the genus of staphylococcus, multi-resistant to antibiotics (S. epidermidis, S. cohni, S. wareneri, S. scuiri, S. chromogenes, S. pasteuri), three methicillin-resistant Staphylococcus aureus strains (MRSA) and two strains of Escherichia coli, producing extended-spectrum β-lactamase (ESBL) responsible for bovine mastitis. Our results indicated that the antimicrobial activities of eight EOs varied significantly among the types of EOs and bacterial species. Thymus capitatus and Trachyspermum ammi EOs display important antibacterial activity against all tested strains, with the inhibition zone diameters situated between 20 and 45 mm, while EOs of Artemisia absinthium, Eucalyptus globulus, Eucalyptus camaldulensis, Myrtus communis and Mentha pulegium exerted an intermediate activity. For Cymbopogon citratus, this effect depends on bacteria species. In fact, an important effect was observed against S. warneri, S. epidermidis, S. cohenii, S. pasteuri and MRSA (EC 39+) strains. In addition, the important lytic effect was observed against MRSA strains, showing that Gram-positive bacteria were more sensitive to T. capitatus EO than Gram-negative ones. Concerning the characterization of the mode action of T. capitatus, experiments of kill-time, bacteriolytic, loss of salt tolerance and loss of cytoplasmic material showed that the used EO was able to destroy cell walls and membranes followed by the loss of vital intracellular materials. In addition, it inhibits the normal synthesis of DNA, causing the bacterial death of E. coli and MRSA strains. This study shows the potential of using of EOs, particularly T. capitaus, to inhibit the growth of Gram-positive and Gram-negative bacteria multi-resistant to antibiotics causing bovine mastitis.

Synergistic activity of Thymus capitatus essential oil and cefotaxime against ESBL-producing Klebsiella pneumoniae

ABSTRACT The objective of the current study was to evaluate the interaction between Tunisian Thymus capitatus essential oil (EO) and cefotaxime against Extended-Spectrum Beta-lactamases (ESBLs) producing Klebsiella pneumoniae hospital strains. GC-MS revealed that the major component of EO was found to be carvacrol (69.28%). The EO exerts an advanced bactericidal effect against all strains. Synergy between EO and cefotaxime was obtained by combined disk diffusion and checkerboard techniques. Combined use of EO and cefotaxime reduced the MIC of imipenem by 8- to 128-fold for all strains (fractional inhibitory concentration index ˂ 0.5, synergy). The time kill curve assay confirmed the advanced activity of combinatory effects of EO and cefotaxime, with total reduce of bacterial number (CFU/mL) after 6 h of culture. Synergistic activity of the combination between EO and cefotaxime constitute an important strategy as therapeutical option to combat infections caused by ESBLs producing Klebsiella pneumoniae.

Phytochemical Analysis, In vitro Assessment of Antioxidant Properties and Cytotoxic Potential of Thymus capitatus Essential Oil

Essential oils (EOs) of medicinal plants became a matter of interest in scientific research because of their potential of utilization for several therapeutic purposes, The EO of Thymus capitatus has been traditionally used in treatment of several conditions related to skin, muscles, and respiratory system, to reduce fever, and to stimulate menstrual flow in addition to its anti-bacterial properties. To chemically analyze the components of the EO of Thymus capitatus and to evaluate its anti-cancerous and anti-oxidant activity on breast cancer cells (T47D), colorectal adenocarcinoma cells (CACO2), and normal human fibroblasts (MRC5). The EOs were extracted by hydro-distillation. Gas chromatography and mass spectrometry were used to analyze the extracts. Cell viability was assessed using three different assays; MTT, trypan blue and neutral red assays. Antioxidant activity was assessed using DPPH scavenging assay. Cell apoptosis was assessed using DNA fragmentation tests and Annexin V-propidium iodide assay. Morphological analysis of cells was assessed using light microscopy and DAPI staining. Twenty-two different compounds were identified in the essential oil of T. capitatus leaves including Thymol (44.34%) and Carvacrol (38.89%) in addition to 20 minor components. The oil extract exhibited a significant inhibitory action on the three cell lines. The viability assays showed significantly higher (p<0.05) IC50 in the fibroblast cell line than the other two cell lines. The selectivity index was higher in T47D cell line compared to CACO II cell line. For apoptosis assessment, DNA fragmentation in T47D cells was significantly correlated with the extract concentration. The membrane polarity was disrupted in an increasing manner (15.60±1.13, 35.73±1.69 and 46.53±2.51) as the extract concentration (20.22, 40.45, and 80.9µg/ml, respectively) increased. On the cellular level, morphological changes including cell shrinkage, chromatin condensation and nuclear fragmentation in addition to marginalization of chromatin, vacuolization of cytoplasm and formation of micronuclei was clearly visible. The extract showed high anti-oxidant activity with an IC50 of 6.4µg/ml. Anti-oxidant activity was dose-dependent; double IC50 (80.9µg/ml) exhibited the highest antioxidant activity whereas the lowest antioxidant activity was observed for the ½ IC50 (20.225µg/ml). The oil extract exerted an inhibitory action lipid peroxidation. Thymus capitatus EO is a potential anti-oxidant and anti-neoplastic agent against breast and colon carcinomas due to its high selectivity for cancer cells compared to normal cell lines.

Essential Oil Stabilisation by Response Surface Methodology (RSM): Nanoemulsion Formulation, Physicochemical, Microbiological, and Sensory Investigations.

This manuscript aimed to optimise the encapsulation of Thymus capitatus essential oil into nanoemulsion. Response Surface Methodology results were best fitted into polynomial models with regression coefficient values of more than 0.95. The optimal nanoemulsion showed nanometer-sized droplets (380 nm), a polydispersity index less than 0.5, and a suitable Zeta potential (-10.3 mV). Stability results showed that nanoemulsions stored at 4 °C were stable with the lowest d3,2, PolyDispersity Index (PDI), and pH (day 11). Significant ameliorations in the capacity to neutralise DPPH radical after the encapsulation of the antimicrobial efficacy of thyme essential oil were recorded. S. typhimurium growth inhibition generated by nanoencapsulated thyme essential oil was 17 times higher than by bulk essential oil. The sensory analysis highlighted that the encapsulation of thyme essential oil improved enriched milk's sensory appreciation. Indeed, 20% of the total population attributed a score of 4 and 5 on the scale used for milk enriched with nanoemulsion. In comparison, only 11% attributed the same score to milk enriched with bulk essential oil. The novel nanometric delivery system presents significant interest for agroalimentary industries.

Lethal Toxicity of Thymus capitatus Essential Oil Against Planococcus citri (Hemiptera: Pseudococcidae) and its Coccinellid Predator Cryptolaemus montrouzieri (Coleoptera: Coccinellidae)

Abstract Botanical extracts, including essential oils, are promising alternatives to synthetic insecticides for pest control. In this study, we evaluated the fumigant toxicity of an essential oil extracted from Thymus capitatus (L.) Hoffmanns. & Link against the citrus mealybug, Planococcus citri Risso (Hemiptera: Pseudococcidae), and its coccinellid predator Cryptolaemus montrouzieri Mulsant (Coleoptera: Coccinellidae) under laboratory conditions. Gas chromatography–mass spectrometry analysis indicated that the major chemical compounds identified from T. capitatus were carvacrol (65.15%), followed by p-cymene (11.79%) and γterpinene (7.48%). High mortality levels were registered for P. citri larvae (up to 100%) and adults (up to 96%) when exposed to the tested essential oil. The median lethal concentration values calculated for P. citri adults were higher than for larvae. Thymus capitatus essential oil applied at 10 and 20 µL/Lair showed high toxicity towards C. montrouzieri adults. These results highlighted the efficacy of T. capitatus essential oil as a promising tool to control P. citri in Tunisia. However, the adverse effects of this oil towards C. montrouzieri should be taken into consideration to enhance its practical implication in integrated pest management.

Proapoptotic and Anticancer Potentials of Thymus capitatus Essential Oil on Colon Cancer Stem Cells

Proapoptotic and Anticancer Potentials of Thymus capitatus Essential Oil on Colon Cancer Stem Cells

Composition phytochimique et activités antioxydante et antimicrobienne des huiles essentielles de Thymus capitatus et de Rosmarinus officinalis de Tunisie

Introduction. Essential oils and their components are currently of great interest as a potential source of highly bioactive natural molecules. They are being studied for their possible use as safe alternative for food protection against oxidation and microbial spoilage. Objective. This study aimed on the phytochemical prospection of Thymus capitatus and Rosmainus officinalis essential oils and their oral toxicity evaluation. Material and methods. Chemical analysis of tested essential oils was carried out using gas chromatography combined to mass spectroscopic (GC-MS). Their safety limit was evaluated by acute toxicity. The antioxidant activity was estimated using in vitro methods. The antimicrobial activity was evaluated against twelve pathogenic germs. Results. Results showed that carvacrol and 1,8-cineol were the major compounds of Thymus capitatus and Rosmarinus officinalis essential oils. Acute toxicity results exhibited that both tested essential oils were inoffensive at 2000 mg/kg. Additionally, Thymus capitatus essential oil presented higher antioxidant activity than Rosmarinus officinalis: 2,2-diphényl-1-picrylhydrazyl (DPPH) assay results showed lower IC50 for Thymus capitatus essential oil than Rosmarinus officinalis. Concerning the antimicrobial results, Thymus capitatus essential oil presented greater efficacy than R. officinalis. Indeed, the minimal growth inhibition diameter generated by thyme essential oil exceeded 38 mm (except for Salmonella typhirium) and reached 60 mm (against C. tropicalis and C. albicans). However, the maximal growth inhibition diameter generated by R. officinalis essential oil was limited to 36 mm (against Shigella sonnei). Conclusion. Overall, Thymus capitatus and Rosmarinus officinalis essential oils have strong potential applicability for pharmaceutical industries.

Evaluation of the antimicrobial effect of Thymus capitatus Essential Oil (EO) Extract on Bacteria Isolated from Urinary Tract Infection

Evaluation of the antimicrobial effect of Thymus capitatus Essential Oil (EO) Extract on Bacteria Isolated from Urinary Tract Infection

Flexible mats as promising antimicrobial systems via integration of Thymus capitatus (L.) essential oil into PLA.

Aim: To develop electrospun mats loaded with Thymus capitatus (L.) essential oil (ThymEO) and to study their morpho-mechanical and antimicrobial properties. Materials & methods: Poly(lactic acid) (PLA) mats containing ThymEO were prepared by electrospinning. The effect of ThymEO on the morpho-mechanical properties of fibers was assayed by scanning electron microscopy and dynamometer measurements. The antimicrobial activity of ThymEO delivered either in liquid or vapor phase was assessed through killing curves and invert Petri dishes method. The cytotoxicity was also investigated. Results: The mechanical properties were enhanced by integrating ThymEO into PLA. Both liquid and vapors of ThymEO released from mats caused reductions of microbial viable cells. Negligible cytotoxicity was demonstrated. Conclusion: PLA/ThymEO delivery systemscouldbe suitable for treating microbial infections.

Antimicrobial Effect of Essential Oil of Thymus capitatus from Northern Cyprus and Its Gargle Preformulation

Aims: The aim of this study is to prepare herbal gargle preformulations making use of essential oil of aerial parts of Thymus capitatus growing wild in Northern Cyprus and comparing antimicrobial efficacy between these formulations with pure essential oil.
 Place and Duration of Study: Department of Pharmaceutical Technology, Faculty of Pharmacy, Near East University, Nicosia, TRNC and Department of Pharmaceutical Microbiology, Faculty of Pharmacy, Ankara University, Ankara, Turkey, between January 2017 and June 2017.
 Methodology: Preformulations with three different concentrations of Thymus capitatus essential oil were prepared by using simple preparation method. Preformulation studies were done in lab with less than 500 ml. There is not specific process parameters. Manufacturing process and process parameters will be clarified with further studies. These compositions and the essential oil were tested in-vitro for antimicrobial activity studies by using broth microdilution method. Staphylococcus aureus ATCC 43300, Staphylococcus aureus ATCC 25923, Staphylococcus epidermidis ATCC 12228, Bacillus subtilis ATCC 6633, Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 29212, Klebsiella pneumoniae RSKK 574, Salmonella paratyphi C, Pseudomonas aeruginosa ATCC 9027, Pseudomonas aeruginosa ATCC 27853 as bacteria and Candida albicans ATCC 10231, Candida parapsilosis ATCC 22019 as yeasts were used for antimicrobial activity tests.
 Results: All trials were found to be more effective than EO, and a significant effect was observed when compared to the values ​​of standard antimicrobial agents.
 Conclusion: TheThymus capitatus growing in Northern Cyprus could be used as a herbal raw material, essential oil source in developing herbal gargle preformulations to reduce fungal and bacterial infections in mouth.

Correlation between chemical composition and antibacterial activity of some Lamiaceae species essential oils from Tunisia

BackgroundLamiaceae family is one of the most diverse and common plant families in terms of ethnomedicine due to their potential therapeutic effects. The aim of this study is to investigate the correlation between the chemical composition and the antibacterial effect of five essential oils from this family against five reference bacterial strains responsible of nosocomial diseases and foodborne illnesses.MethodsThe commercial essential oils of Tunisian Rosmarinus officinalis, Thymus capitatus, Origanum majorana and Salvia officinalis were analyzed by GC/FID and GC-MS. Essential oils were evaluated for their antibacterial activities by disc diffusion and microbroth dilution methods against five reference bacterial strains: Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica, Bacillus subtilis and Staphylococcus aureus. The inhibition zone diameter values and the twenty major compounds of the selected essential oils were subjected to PCA and HCA analysis.ResultsAnalysis by GC/FID and GC/MS allowed the identification of ninety-one components representing 96.0 to 98.2% of the total oils. The different component contents varied according to the species. The main components were carvacrol, 1,8-cineole, α-thujone, α-terpineol and α-pinene. The PCA and the HCA of the selected essential oil components and the inhibition zone diameter (IZD) values identified four species groups and subgroups. Each essential oils group constituted a chemotype responsible for their bacterial inhibition ability. Thymus capitatus essential oil showed the strongest antibacterial activity with MBC ranging from 0.73 to 2.94 mg mL− 1.ConclusionRosmarinus officinalis, Thymus capitatus, Origanum majorana and Salvia officinalis essential oils have shown promising antibacterial activities against reference bacterial strains responsible for nosocomial diseases and foodborne illnesses.

Inhibition of bacterial growth on marble stone of 18th century by treatment of nanoencapsulated essential oils

Controlling of cultural heritage biodeterioration is a serious problem in the world. Chemical biocides, used to kill unwanted microorganism, can represent a risk for human health and environment, and interfere with the restoration material. Natural biocides could represent a valid alternative to conventional ones. In this study we report the use of nanocapsules suspensions (NCs) loaded with Origanum vulgare and Thymus capitatus essential oils (EOs) to contrast the development of bacterial growth of two microrganisms (Escherichia coli and Kokuria rhizophila) on the marble stone from 18th century church altar. No structural change was observed on the stone after treatment with the aqueous suspension containing nanoparticles as evidenced by SEM-EDX analysis. The nanostructurate systems (EO-NCs) were able to inhibit the bacterial grow on the stone pretreated with bacterial inoculum as showed by agar discs contact test. Nanocapsules, based on biodegradable and biocompatible polymer (poly(ε-caprolactone)), loaded with thyme EO are more efficient than nanocapsules loaded with oregano EO. The obtained results evidenced the potential of these natural biocides in the treatment of biodeteriorated cultural heritage.

Chitosan Beads Incorporated with Essential Oil of Thymus capitatus: Stability Studies on Red Tilapia Fillets.

Red Tilapia is one of the most consumed but perishable fish in the world. As a result, it requires preservation methods for safe consumption without affecting its organoleptic characteristics. Chitosan encapsulating essential oils have shown to be an excellent food conservation method. For that reason, we carried out the study of the protective effect on red Tilapia fillets with chitosan beads (CB) incorporated with Thymus capitatus (TCEO) essential oil at 500, 1000, and 2000 mg/L to assess the conservation of the fillets. The TCEO composition was characterized by gas chromatography-mass spectrometry (CG-MS). For the other side, CB was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction spectroscopy (XRD), thermogravimetric analysis (TGA), and Scanning electron microscopy (SEM). The protective effect of the beads was tested against the Gram-positive and Gram-negative bacteria growth for four weeks. The results showed an inhibition effect in Gram-positive bacteria at higher TCEO concentration (1000 and 2000 mg/L). Besides that, the pH, total volatile basic nitrogen (T-BNV-N), color, and fillet texture were evaluated as quality attributes. The results suggested that the incorporation of the CB-TCEO allowed a higher contact of the active compounds with the food surface, which reflected more excellent stability. The quality attributes of the fillets were preserved for 26 days, suggesting its uses for the treatment for perishable food.

Combined effect of Thymus capitatus and Cinnamomum verum essential oils with conventional drugs against Candida albicans biofilm formation and elucidation of the molecular mechanism of action

Biofilm formation by the pathogenic strain Candida albicans (C. albicans) is a crucial virulence factor on biotic and abiotic surfaces especially in medical devices. The present study investigated the effects of Cinnamomum verum and Thymus capitatus essential oils (EOs) and their combination with antifungal drugs on the development of biofilm and mature biofilm. The molecular mechanism of action was also investigated. Results showed that C. verum and T. capitatus EOs were broadly effective against C. albicans biofilm formation exhibiting 85.57% and 80.6% inhibition at half MIC values, respectively. Furthermore, they showed 92.79 and 94.46% eradication of C. albicans mature biofilm at 2xMIC values. Moreover, these EOs were able to reduce the production of secreted aspartic proteases by >90% at 0.75xMIC. The antibiofilm potency was improved when EOs were combined with AMB, effectively eradicating C. albicans mature biofilm on central venous catheter (CVC). Transcriptomic analyses indicated that EOs, especially when combined with AMB, down-regulate Ras-cAMP-Efg and MAPK signaling genes. In addition, EOs and their combination with AMB significantly inhibited the expression of adhesion and secreted aspartyl proteinase virulence factor genes. Our results demonstrated that C. verum and T. capitatus EOs and their combination with AMB could provide an effective treatment against C. albicans biofilm on medical devices.

Antimicrobial Effect of Thymus capitatus and Citrus limon var. pompia as Raw Extracts and Nanovesicles.

In view of the increasing interest in natural antimicrobial molecules, this study screened the ability of Thymus capitatus (TC) essential oil and Citrus limon var. pompia (CLP) extract as raw extracts or incorporated in vesicular nanocarriers against Streptococcus mutans and Candida albicans. After fingerprint, TC or CLP were mixed with lecithin and water to produce liposomes, or different ratios of water/glycerol or water/propylene glycol (PG) to produce glycerosomes and penetration enhancer vesicles (PEVs), respectively. Neither the raw extracts nor the nanovesicles showed cytotoxicity against human gingival fibroblasts at all the concentrations tested (1, 10, 100 μg/mL). The disc diffusion method, MIC-MBC/MFC, time-kill assay, and transmission electron microscopy (TEM) demonstrated the highest antimicrobial potential of TC against S. mutans and C. albicans. The very high presence of the phenol, carvacrol, in TC (90.1%) could explain the lethal effect against the yeast, killing up to 70% of Candida and not just arresting its growth. CLP, rich in polyphenols, acted in a similar way to TC in reducing S. mutans, while the data showed a fungistatic rather than a fungicidal activity. The phospholipid vesicles behaved similarly, suggesting that the transported extract was not the only factor to be considered in the outcomes, but also their components had an important role. Even if other investigations are necessary, TC and CLP incorporated in nanocarriers could be a promising and safe antimicrobial in caries prevention.

Activity of Thymus capitatus essential oil components against in vitro cultured Echinococcus multilocularis metacestodes and germinal layer cells.

The essential oil (EO) of Thymus capitatus, seven fractions (F1-F7) obtained from silica gel chromatography, and several pure EO components were evaluated with respect to in vitro activities against Echinococcus multilocularis metacestodes and germinal layer (GL) cells. Attempts to evaluate physical damage in metacestodes by phosphoglucose isomerase (PGI) assay failed because EO and F1-F7 interfered with the PGI-activity measurements. A metacestode viability assay based on Alamar Blue, as well as transmission electron microscopy, demonstrated that exposure to EO, F2 and F4 impaired metacestode viability. F2 and F4 exhibited higher toxicity against metacestodes than against mammalian cells, whereas EO was as toxic to mammalian cells as to the parasite. However, none of these fractions exhibited notable activity against isolated E. multilocularis GL cells. Analysis by gas chromatography-mass spectrometry showed that carvacrol was the major component of the EO (82.4%), as well as of the fractions F3 (94.4%), F4 (98.1%) and F5 (90.7%). Other major components of EO were β-caryophyllene, limonene, thymol and eugenol. However, exposure of metacestodes to these components was ineffective. Thus, fractions F2 and F4 of T. capitatus EO contain potent anti-echinococcal compounds, but the activities of these two fractions are most likely based on synergistic effects between several major and minor constituents.

The Effect of Edible Chitosan Coatings Incorporated with Thymus capitatus Essential Oil on the Shelf-Life of Strawberry (Fragaria x ananassa) during Cold Storage.

The strawberry is a fruit appreciated in the food industry for its high content of bioactive compounds. However, it is considered a highly perishable fruit, generally attacked by pests of phytopathogenic origin, which decreases its shelf-life. Normally, to diminish the losses caused by pathogenic microbes, coatings of polysaccharides in combination with natural products like essential oils are applied. In this work, we describe the effect of edible coatings from chitosan (CT) incorporating Thymus capitatus essential oil (TCEO), applied to strawberries stored under refrigeration conditions (5 ± 0.5 °C). Different concentrations of TCEO were applied to chitosan coatings, with different effects on the physical and microbiological properties of the strawberries. All the products had greater acceptance and quality than the controls, being more effective those with essential oil incorporation. It is noteworthy that all the essential oil treatments lead to an increase in the shelf-life of strawberries of up to 15 days. Scanning electron microscopy (SEM) analysis of the microstructure showed a decrease in compactness with TCEO introduction, but without compromising food preservation after 15 days. In addition, treated strawberries delayed the loss of physicochemical and antioxidant properties, due to protection against the microbial development of aerobic mesophylls, molds, and yeasts.

Chitosan films incorporated with Thymus capitatus essential oil: mechanical properties and antimicrobial activity against degradative bacterial species isolated from tuna (Thunnus sp.) and swordfish (Xiphias gladius).

Chitosan-based coatings and films have been widely studied, demonstrating to be an efficient and eco-friendly approach to extend the shelf life of food products. The effect of incorporating Thymus capitatus essential oil (TCEO) at different concentrations (0.5, 1.0, and 1.5% w/w) on physical, mechanical and antimicrobial properties of chitosan films was studied. The antimicrobial activity of the films was evaluated by agar diffusion method, against 23 spoiling microorganisms isolated from tuna and swordfish (ten Shewanella baltica, one S. morhuae, one S. putrefaciens, two Pseudomonas fluorescens, two P. fragi, five Serratia spp., one Aeromonas molluscorum, and one Acinetobacter radioresistens) and Shewanella putrefaciens ATCC 49138. The films exerted antimicrobial activity against all the tested strain, although not proportional to increasing TCEO concentration. In particular, S. baltica was the most sensitive species and the inhibition was stable after 72h. In general, TCEO incorporation in chitosan films, significantly (p < 0.05) decreased the water permeability (from 0.577 ± 0.060 gmm/kPahm2 at 61% R.U. for chitosan to 0.487 ± 0.037 gmm/kPahm2 for the film with 1.5% TCEO), the elongation at brake (from 27.322 ± 2.35% for chitosan to 14.695 ± 3.99% for the film with 1.5% TCEO) and increased the tensile strength (from 1.697 ± 0.16% for chitosan to 19.480 ± 2.86% for the film with 1.5% TCEO). Moisture content and water contact angle of the films also showed a similar trend with TCEO introduction, because of crosslinking reaction among the polymer chains and TCEO components. Scanning electron microscopy confirmed structure-properties relationships. These results suggest chitosan films incorporated with TCEO as an alternative treatment to inhibit the growth of degradative bacteria with potential application in the fish industry. The importance of testing more than one strain of the same bacteria species to evaluate the effectiveness of chitosan-essential oils coatings was also demonstrated.

Thymus capitatus essential oil ameliorates pasteurization efficiency.

This work aims to characterize Thymus capitatus essential oil and to investigate its preservative effects on raw milk quality alone or combined to pasteurization heat treatment. To study its preservative effect, 1mgl-1 of T. capitatus essential oil, characterized by GC-MS, was added to pasteurized or raw milk. The evaluation of milk quality was made by consulting samples total acidities, peroxide values and their total microbial counts, as compared to control milks. Assays were made immediately and after every 48h of incubation at room temperature throughout 6days. Results showed that the incorporation of T. capitatus EO to pasteurized milk was the most efficient treatment that inhibited milk deterioration. Combining pasteurization to EO incorporation into raw milk inhibited completely the contaminant bacterial growth to the second day of incubation. Moreover, until the fourth day, no statistical differences have been recorded on the total acidity of incorporated and pasteurized milk samples, while raw milk acidity exceeded 55g of lactic acid equivalentl-1. Considering milk fat oxidation, adding T. capitatus EO to pasteurized milk has significantly retarded milk peroxide production to day 4. In conclusion, Thymus capitatus essential oil, combined to pasteurization, presents an interesting potency to act as milk stabilizer.