Laurel Oil Research Articles

Antifungal activity of thyme, oregano and laurel essential oils against Aspergillus niger Tiegh

A range of pathogenic fungi are associated with postharvest fruit spoilage in storage that cause significant economic losses every year. To control postharvest mycoses, fungicide application is the usual practice. However, the use of essential oils as an alternative strategy to chemical fungicides has been considered for management of the postharvest fruit decay in order to ensure nonnegative impact on human health. Mycotoxigenic fungi Aspergillus niger Tiegh. is economically important pathogen which causes postharvest black rot on various fruits. The present study evaluated the vapor phase antifungal activity of three essential oils - thyme (Thymus vulgaris L.), oregano (Origanum vulgare L.) and laurel (Laurus nobilis L.) against postharvest pathogen A. niger. The antifungal activity of selected essential oils were evaluated by disc volatilization method on PDA medium. The vapor phase of all tested oils showed a significant (p < 0.05) fungistatic growth inhibition of pathogen A. niger, where thyme oil achieved the highest pathogen inhibition (99.8%), while laurel oil was less effective (36.3%). The obtained results suggest that the tested vapor phase (especially of thyme and oregano oils) could potentially be extremely useful fumigants to prevent and control the fruit rot in storage.

GC-MS Analysis and Evaluation of Essential Oils as Volatile Biopesticides: Assessing Their Acaricidal Potential against Varroa destructor

Honey bees are crucial for ecosystem pollination and honey production, yet the Varroa destructor mite hinders their productivity and health. Efforts to manage Varroa mites with synthetic pesticides have had limited success, highlighting the need for naturally derived acaricides as a primary option. However, the acaricidal efficacy of essential oils from Salvia officinalis L. (sage), Cannabis sativa (hemp), and Laurus nobilis (laurel) remains to be fully understood. This study aims to investigate the acaricidal efficacy of these three essential oils at varying concentrations and their impact on honey production, focusing on the efficient reduction in Varroa mites. The sugar roll method was employed to assess Varroa mite infestation levels, while GC-MS analysis was utilized to verify the composition of the essential oils. Honey production measurements were also performed. The efficacy rates (%) at concentrations of 15%, 10%, and 5% for hemp oil were 95.4% ± 0.30%, 85.71% ± 0.85%, and 64.48% ± 0.26%, respectively; for sage oil, they were 81.08% ± 0.57%, 69.42% ± 1.72%, and 50.35% ± 0.70%; and for laurel oil, they were 68.96% ± 0.34%, 54.66% ± 0.37%, and 33.58% ± 0.30%, respectively. Key compounds identified include trans-caryophyllene, α-pinene, and viridiflorol in hemp oil; myrcene, limonene, and β-caryophyllene in sage oil; and phytol, β-myrcene, and n-heneicosane in laurel oil. The overall findings indicate that hemp oil is highly effective in controlling Varroa mites. However, further research is needed to evaluate its potential side effects on bees to ensure its sustainability and safety.

Bioactivity of essential oils in the control of Sitophilus ssp.

Brazil is the largest rice producer outside of Asia, and the large production of this grain in the Brazilian territory has aspects that affect its productivity. Among all the influencing aspects is the rice weevil, Sitophilus ssp. Considering the needs of the grain industry and the market that seeks products without toxic residues, the work evaluated the bioactivity of the essential oils of laurel (Laurus nobilis), eucalyptus (Eucalyptus citriodora), and mint (Mentha piperita) on the coleopteran Sitophilus ssp. The insects used were obtained from infested silos and kept in a breeding room at a controlled temperature. For testing the bioactivity of essential oils, essential oils were used at concentrations of 1%, 5%, and 10%. The adult insects used were placed on the plates and the count of live individuals (rice weevil) was performed at times of 15 min., 30 min., 60 min., 6h, 12h, and 24h. All tested oils showed efficiency in insect mortality. The chemical characterization of essential oils was performed by gas chromatography coupled with mass spectrometry, indicating the presence of oxygenated monoterpenes in the three essential oils analyzed.

Effect of xylanase addition and ultrasonic pretreatment on the yield and volatile profile of bay laurel and sage essential oil

In order to increase the yield of essential oils in hydrodistillation of bay laurel and sage, the effect of pretreatment with ultrasound and enzymes (under different conditions of xylanase pretreatment) was studied. The effects of the optimized conditions (concentration of xylanase 0.20 mg/mL in buffer pH=6.5 at 40°C for 4 h) during the enzymatic pretreatment showed that despite the optimization the activity of xylanase did not significantly affect the quantity and quality of essential oils of bay laurel and sage. Ultrasonic pretreatment prior to enzymatic pretreatment with the addition of optimized xylanase resulted in increased yields of dominant compounds (α-thujone 27.42%, β-thujone 12.15%, and camphor 20.94%) in sage essential oil, while in bay laurel the amount of dominant compounds (1,8-cineole 24.65% and α-terpenyl acetate 11.05%) was not significantly increased. Despite minor changes, ultrasonic and enzymatic pretreatment of the plant materials did not significantly affect the chemical composition of the essential oils of bay laurel and sage compared with the control without pretreatment, as confirmed by the Spearman rank test (p < 0.05). The main advantage of ultrasonic extraction is the reduction in pretreatment time. Ultrasonic pretreatment for only 10 min before enzymatic pretreatment resulted in a 50% increase in sage essential oil yield and a 40% increase in bay laurel essential oil yield.

Prediction of Secondary Metabolites Content of Laurel (Laurus nobilis L.) with Artificial Neural Networks Based on Different Temperatures and Storage times

Bay laurel leaves, also known as bay leaves, are an important herb in many cuisines around the world. In addition to their use in cooking, bay leaves have also been used for their medicinal properties and are thought to have anti-inflammatory and antimicrobial effects. Gas chromatography/mass spectrometry (GC-MS) device was used to determine the secondary metabolites in the essential oil of bay laurel leaves samples kept at different temperatures (−22, −20, −18, 2, 4, 6, and 22°C) and storage times (1, 2, and 3 months). In this research, temperature (°C) and storage time (month) were used as input parameters in the neural network. On the other hand, alpha-pinene, beta-pinene, sabinene, 1.8-cineole, gamma-terpinene, cymenol, linalool, borneol, 4-terpineol, caryophyllene, sabinene, alpha-terpineol, germacrene-D, alpha-selinene, methyl eugenol, caryophyllene oxide, spathulenol, eugenol, and beta-selinenol were used as an output parameter. Considering the R2 values obtained from the artificial neural network analysis, R2 values of 0.97156 for the test, 0.98978 for the training, 0.98998 for the validation value, and 0.98831 for all values were obtained.

Effects of Adding Laurel (Laurus nobilis) Essential Oil to the Diet of Tilapia Fish on Growth and Intestinal Histology

The effects of adding laurel oil to the experimental diet on growth performance, biochemical compositions of fish and feeds, sand liver and intestine histology in Nile tilapia (Oreochromis niloticus) juveniles were evaluated. 180 fish (12±0.02 g) were used in the study. They were randomly placed in 12 tanks with a volume of 500 liters, with 15 fish per tank. The commercial laurel oil was added to the diets at 0, 0.3, 0.6, and 1.2%. The fish were fed with experimental diets twice a day as apparent satiation for 60 days. In the current study, weight gain (WG), feed conversion ratio (FCR), specific growth rate (SGR) and survival rates (SR) were statistically similar (p&gt;0.05). While no difference was observed between protein and ash values in the biochemical analysis of fish, lipid values were found to be lower in the 0.3% and 0.6 supplemented groups compared to the control and 1.2% supplemented groups. In addition, there was no statistical difference in protein, lipid, and ash values in the biochemical composition of the feeds. In the study, essential oil components of Laurus nobilis oil such as Linalool, Elemene, Trans-Caryophyllene, Cis-α-Bisabolene, Α-Terpinyl Acetate, Methyleugenol, β-Eudesmol were determined in low levels. The addition of 0.3% laurel oil to the diet did not cause histopathological findings, and it was found to improve liver and intestinal tissues. In conclusion, it is suggested that 0.3% laurel oil addition can be used as a feed additive in tilapia culture, especially considering the data obtained from growth and histological analyzes. Further studies are deserved need to examine the effects of laurel oil on immunity and resistance to various stress factors in other fish.&nbsp;

The Use of Enzyme Systems of the Genus Prunus for the Production of Benzaldehyde

Abstract Aim Benzaldehyde occurs in a number of plants, especially in the family Rosaceae and in particular in the genus Prunus. In nature, there are more than 100 genera and 3,000 species in the Rosaceae family. The objective of this study was to investigate the chemical composition of leaf essential oil of peach (Prunus persica L.) and cherry laurel (Prunus laurocerasus L.) as a new potential source of natural benzaldehyde. Methods The essential oil was prepared by hydrodistillation, and chemical constituents were determined by GC-FID, GC-MS and chromatographic profiles were compared with each other. Results The results show that essential oil obtained from peach and cherry laurel leaves appear to be a promising source of natural benzaldehyde. Under laboratory conditions the benzaldehyde content in peach and cherry laurel leaves reached 95.5% and 99.7%, respectively. Conclusions Laboratory and pilot experiments confirmed that by processing of 200–300 kg of green leaves of various species of the genus Prunus, especially peach and cherry laurel, 1 kg of benzaldehyde can be obtained.

Biological control of Citrus brown spot pathogen, “Alternaria alternata” by different essential oils

ABSTRACT The antifungal effects of laurel, myrtle and peppermint essential oils and their combinations were investigated in vitro on two strains of Alternaria alternata mycelial growth and in vivo on detached Citrus leaf disease incidence. Myrtle essential oil was rich in α-pinene and 1,8-cineole while peppermint essential oil in menthol and menthone. 1,8-Cineole was the main component of the essential oils from laurel, laurel + myrtle and peppermint + laurel. The combined peppermint and myrtle essential oil was characterized by the predominance of menthol and 1,8-cineole. All tested essential oils, incorporated in potato-dextrose agar, inhibited A. alternata mycelial growth and had a fungistatic effect at concentration 3 mg/mL of medium. A great synergism was detected between peppermint and laurel essential oils against the two strains of A. alternata. The combined laurel and peppermint essential oil reduced mycelial growth rates of inoculated detached leaves at concentration above 1.5 mg/mL.

Effect of different plants’ aromatic essential oils on frozen Awassi lamb meat’s chemical and physical characteristics

The effect of drenching Awassi lambs with three aromatic essential oils from sage (Salvia officinalis L.), clove (Syzygium aromaticum L.), and laurel (Laurus nobilis L.) was investigated on meat chemical and physical characteristics, and oxidative and deterioration measurements. Twenty-four Awassi lambs, five to six months old, were divided into four groups. A concentrated diet was provided to the lambs at a rate of 3% of the body weight. The treatments were as follows: T1 was served as the untreated control, while T2, T3, and T4 were drenched with oils of sage, clove, and laurel, respectively. Drenching was carried out using water-soluble capsules containing 500 mg oil/capsule/day. Treatments lasted 90 days. At the end of the treatment period, the animals were fasted overnight and slaughtered. The carcasses were cleaned and kept at 4°C for 24 h. The longissimus dorsi (LD) muscle was then separated and preserved in a plastic bag for three preservation periods: no freezing and 30 days and 60 days freezing at −18°C. Several physical, fat, and protein stability analyses of meat were done after the preservation periods. The results indicated no significant effect of drenching Awassi lambs with different aromatic essential oils on the meat’s physical and chemical characteristics. However, these oils, especially clove oil, affected fat and protein stability with increasing preservation period by freezing.

Using of Different Kinds of Aromatic Oils with Feeding on Some Productive Traits in Awassi Lambs

This study was conducted in the animal farm of the College of Veterinary Medicine/Tikrit University for the period from 01/10/2019 to 31/12/2019 to investigate the effect of using different kinds of aromatic oils on some productive traits in Awassi lambs. Twenty Awassi lambs aged between 5-6 month and divided according to weight into four group and hens in an individual cages, the study lasted for 90 day. concentrate diet provided to the lambs at 3% of their body weight. the treatment were as follows : T1 was a control group without drenching, T2 drenched with sage oil, T3 drenched with clove oil and T4 drenched with laurel oil. drenching process was done manually by using water-soluble capsules each one contain 500 mg of oil, each lambs was given one capsule/day. which is pushed by using a plastic tube in to the beginning of esophagus. to study the effect of these oils on weight characteristics, body dimensions and wool characteristics. The results showed that there was no significant effect of the treatments on body weight characteristics. As for the measurements of the body dimensions after a month of the experiment, laurel oil, clove oil and sage oil had a significant effect on the chest circumference, the width of the body at the front, the width of the body at the back and BCS, and also the parameters had a significant effect on the measurements of body dimensions At the end of the experiment, the characteristics of the height of the body at the front, the height of the body at the back, the circumference of the chest, and the length of the body. As for the characteristics of the wool, the oils used led to a decrease in the percentage of clean wool and an increase in the length of the fiber compared to the control.

Prevention of Saprolegniasis in rainbow trout (Oncorhynchus mykiss) eggs using oregano (Origanum onites) and laurel (Laurus nobilis) essential oils

The present study investigated the antifungal effects of essential oils of oregano (Origanum onites) and laurel (Laurus nobilis) on Saprolegniasis, a disease that occurs in rainbow trout eggs during the incubation period. Oregano and laurel were ground after drying, and essential oils were obtained by water distillation method using a Clevenger apparatus. The essential oils were added to potato dextrose agar (PDA) at the rates of 1-1000ppm, and the minimum inhibitory concentration (MIC) was determined as 250ppm whereas the minimum lethal concentration (MLC) was determined to be 500ppm for both plants. In the in vivo trials, fertilized eggs were treated with predetermined doses either by bathing during water hardening and incubation period or only during incubation period, and death rates were monitored during embryological development. The best larvae hatching rate was determined in 500ppm oregano and 500ppm laurel groups treated during water hardening plus daily as 82.11% and 79.87%, respectively. According to the results, it was determined that oregano and laurel essential oils exhibited better results in all doses compared with the negative control group, and 500ppm dose had a better effect than the positive control group treated with formalin.

Essential Oils of Sage, Rosemary, and Bay Laurel Inhibit the Life Stages of Oomycete Pathogens Important in Aquaculture.

Saprolegnia parasitica, the causative agent of saprolegniosis in fish, and Aphanomyces astaci, the causative agent of crayfish plague, are oomycete pathogens that cause economic losses in aquaculture. Since toxic chemicals are currently used to control them, we aimed to investigate their inhibition by essential oils of sage, rosemary, and bay laurel as environmentally acceptable alternatives. Gas Chromatography–Mass Spectrometry (GC–MS) analysis showed that the essential oils tested were rich in bioactive volatiles, mainly monoterpenes. Mycelium and zoospores of A. astaci were more sensitive compared to those of S. parasitica, where only sage essential oil completely inhibited mycelial growth. EC50 values (i.e., concentrations of samples at which the growth was inhibited by 50%) for mycelial growth determined by the radial growth inhibition assay were 0.031–0.098 µL/mL for A. astaci and 0.040 µL/mL for S. parasitica. EC50 values determined by the zoospore germination inhibition assay were 0.007–0.049 µL/mL for A. astaci and 0.012–0.063 µL/mL for S. parasitica. The observed inhibition, most pronounced for sage essential oil, could be partly due to dominant constituents of the essential oils, such as camphor, but more likely resulted from a synergistic effect of multiple compounds. Our results may serve as a basis for in vivo experiments and the development of environmentally friendly methods to control oomycete pathogens in aquaculture.

Antimicrobial effect of laurel essential oil nanoemulsion on food-borne pathogens and fish spoilage bacteria

This research aimed to apply nanotechnology for nanoformulation of Laurus nobilis essential oil (EO) by ultrasonic emulsification method and characterization of nano-form: particle size, viscosity, polydispersity index, thermodynamic stability, and surface tension. The antimicrobial activity of laurel EO nanoemulsion (LEON) and laurel EO was also investigated against a panel of ten food-borne pathogens and fish spoilage bacteria. The GC–MS analysis of EO revealed that 1,8-Cineole was the main volatile compound. According to disc-diffusion results, LEON was more effective against Gram-positive pathogen bacteria of Staphylococcus aureus and Enterococcus faecalis than EO. Laurel oil demonstrated a higher inhibitory effect against fish spoilage bacteria (6.19 to 18.5 mm). The MICs values of LEON and laurel EO ranged from 6.25 to >25 mg/mL and from 1.56 to >25 mg/mL, respectively. Nanoemulsion and oil exhibited the best bactericidal activity against Pseudomonas luteola. Therefore, LEON can be developed as a natural antimicrobial agent in food industry.

Effect of Enzymatic, Ultrasound, and Reflux Extraction Pretreatments on the Chemical Composition of Essential Oils.

The effect of different hydrodistillation pretreatments, namely, reflux extraction, reflux extraction with the addition of cell wall-degrading enzymes, and ultrasound, on the yield and chemical composition of essential oils of sage, bay laurel, and rosemary was examined. All pretreatments improved essential oil yield compared to no-pretreatment control (40–64% yield increase), while the oil quality remained mostly unchanged (as shown by statistical analysis of GC-MS results). However, enzyme-assisted reflux extraction pretreatment did not significantly outperform reflux extraction (no-enzyme control), suggesting that the observed yield increase was mostly a consequence of reflux extraction and enzymatic activity had only a minute effect. Thus, we show that ultrasound and reflux extraction pretreatments are beneficial in the production of essential oils of selected Mediterranean plants, but the application of enzymes has to be carefully re-evaluated.

Determination of chemical compositions and antifungal activities of laurel and fennel essential oils against fungal disease agents of cypress seedlings

Fusarium oxysporum and Pestalotiopsis funerea are the most common fungal disease agents of conifer seedlings causing root rot and shoot or tip blight diseases. In this study, chemical compositions and antifungal activities of essential oils of fennel (Foeniculum vulgare Mill.) and laurel (Laurus nobilis L.) were determined against root rot and wilt disease agents F. oxysporum and P. funerea in vitro conditions. Chemical compositions of essential oils were determined by using GC-MS analysis. Antifungal volatile phase effects of essential oils were determined on inhibition of mycelial growth in vitro conditions by using different concentrations. The effect of most effective concentrations of essential oils on the morphology of fungal hypha was also determined by using light microscope. GC-MS analysis of essential oils of laurel and fennel plants revealed that eucalyptol (46.97%) and α-terpinyl acetate (19.82%) were major components of laurel; trans-anethole (82.44%) and limonene (5.18%) were major components of fennel essential oils. Volatile phase effects of fennel and laurel essential oils were found to completely inhibit mycelial growth of F. oxysporum at 30.0 and 50.0 µl petri-1 concentrations, respectively. Complete growth inhibition of P. funerea by essential oil of fennel and laurel were observed at relatively lower concentrations (20.0 and 25.0 µl petri-1 concentrations, respectively). Light microscopic observations on hyphae, exposed to volatile phase of the most efficient concentrations of essential oil, revealed considerable structural deformations such as cytoplasmic coagulation, vacuolations and protoplast leakage. In conclusion, our results suggest that essential oils have the potential for use in control of fungal diseases of conifer plants.

Experimental Determination of the Qualitative Composition of Chladone Extracts of Bay Leaf

The features of the use of laurel leaf extracts in food production are considered. The characteristics of the main substances contained in the leaves of the Noble laurel are listed. The chemical composition of Noble laurel proves the prospect of using extracts in food production. The extraction and environmental advantages of extraction with liquefied gases were analyzed, traditional methods of extracting vegetable oil, as well as their comparative characteristics were given. The stages of the technological process of extraction of laurel oil using liquefied chladone are shown, the organoleptic characteristics of the final product are evaluated. In the process of chemical analysis of the refrigerant extract, it was determined that the use of the modern method of chladone extraction with liquefied gases allows extracting the extract with a significantly larger amount of aroma-forming substances. The obtained values of the number of aroma are compared with the indicators of aqueous-alcoholic extract, which exceed the latter several times. Studies of extracts by gas chromatography have been described, as a result of which more than 50 components have been identified, among which fatty acids and ether derivatives are of particular interest. It was revealed that the chladone extract of laurel leaves retains the color, smell and taste of the original plant materials. The results of gas chromatography were compared with literature data on the qualitative composition of bay leaf extracts obtained by microwave extraction and supercritical fluid extraction, as a result of which it was established that chladone extract of bay leaf has the same dominant compound 1,8-cineole. Of particular value are eugenol derivatives, which can act as antioxidant supplements in the treatment of cancer.

Influence of different essential oils on marinated anchovy (Engraulis encrasicolus L. 1758) during refrigerated storage

Abstract This study aims to determine the effect of different essential oils on the physical, chemical and microbiological properties, and the shelf life of the cold marinated anchovies ( Engraulis encrasicolus L. 1758) stored at 4 ± 2 °C. The anchovies were marinated for twenty-four hours at 4 ± 2 °C in brine, consisting of salt (10%), alcohol vinegar (4%) and citric acid (0.2%), and then stored for six months at 4 ± 2 °C in sunflower seed oil. The study consists of the following groups: only sunflower seed oil (group A), 0.1% rosemary oil (group B), 0.1% coriander oil (group C), 0.1% laurel oil (group D) and 0.1% garlic oil (group E). When the results of the TVB-N and microbiological analysis were considered, it were established that all the groups maintained their freshness during the six month period, and that group E containing garlic oil, had the minimum TVB-N ratio and the lowest total mesophilic bacteria count by the end of the storage period.

Oxidative Stability, Affective and Descriptive Sensory Properties of Roasted Peanut Flavored with Oregano, Laurel, and Rosemary Essential Oils as Natural Preservatives of Food Lipids

The objective of the study is to evaluate lipid oxidation stability in roasted peanuts with essential oils as natural antioxidants. Laurel, oregano, and rosemary essential oil (LEO, OEO, and REO, respectively) provide preliminary antioxidant activity determined by free radical scavenging activity (DPPH test) of 61.1, 58.4, and 47.9% and total phenolic content of 10.3, 10.6, and 8.4 mg g−1 for LEO, OEO, and REO, respectively. Essential oil (EO; 0.02% p/p) is added to roasted peanuts and an affective sensory test (nine‐point hedonic scale) shows that samples with OEO have greater values (6.74) than those of other samples (≈6.20). Chemical (peroxide anisidine diene content and Totox values) volatile (hexanal and 2‐heptenal) and sensory (oxidized and cardboard intensity) indicators change over 84 storage days. Samples with EOs show lower values than those for controls decreasing lipid oxidation. Samples with BHT have the lowest values for deterioration indicators. Principal component analysis of EOs for all indicators and samples with EOs shows that LEO and OEO have better antioxidant properties than REO. Coefficient regression between sensory variables peroxide value and hexanal has a good correlation and can be used as a predictor equation. Essential oils can be used as flavor and natural antioxidant agent in roasted peanut.Practical Applications: The authors believe in the importance of replacing the use of synthetic antioxidants with natural antioxidants in foods. Synthetic antioxidants are being questioned by the perception of safety that these offer by consumers. The essential oils present an antioxidant alternative since their components possess these properties and the application of them is a reason for research to be able to provide more information to the food industry. The sensory properties of essential oils are well received by consumers and the potential for their application as functional flavorings is in its initial stages. That is why this research collaborates with the use of the essential oils of oregano, laurel, and rosemary as possible antioxidants and flavors in peanuts roasted or in other food (which is susceptible to oxidative processes) evidenced its antioxidant properties and the modification of taste and sensory perception by the consumers.Oregano, laurel, and rosemary essential oils can be used as antioxidants in peanut products and foods with high lipid content.

Contact toxicity of pine, laurel and juniper essential oils to spirodiclofen-resistant and -susceptible Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) populations

Tetranychus urticae Koch, 1836 (Acari: Tetranychidae) causes significant losses in agricultural production because of it is a polyphagous pest and develops resistance to pesticides in a short time. This study was conducted in 2017-2018 in Isparta, Turkey. Contact toxicities of pine, laurel and juniper essential oils to different developmental stages of a highly spirodiclofen-resistant and a spirodiclofen-susceptible population of T. urticae were investigated. The was aim was to contribute to the development of alternative methods to control in resistant populations. The essential oil solutions were applied using a spray tower at 100 kPa to the leaf surface at 1.2-1.6 mg/cm 2 . The experiments were conducted with three replicates , with 15 individuals each treatment replicate. The highest mortality in adults was 100 % for pine, juniper and laurel oil in the susceptible population, and 59.5% for pine oil, 57.5% for laurel oil and 51.2% for juniper oil in the spirodiclofen-resistant population. In addition, the highest mortality for nymphs was 81.6% for pine oil, 95.2% for laurel oil, 95.7% for juniper oil in the susceptible population, and 50.0% for pine oil, 56.3% for laurel oil and 58.0% for juniper oil in the spirodiclofen-resistant population. In toxicity tests on egg the highest mortality was lower than 55.0% in both populations. As a result, the three essential oils were showed to have a significant effect in the T. urticae population with high level resistance to spirodiclofen.

ANTIBACTERIAL AND ANTI-OXIDANT ACTIVITIES OF LAUREL OIL AGAINST Staphylococcus aureus AND Pseudomonas fluorescence IN Oreochromis niloticus FILLETS

Laurus nobilis L. commonly known as Bay belonging to the family Lauraceae, is one of the most useful plant used in foods as a spice in Mediterranean cookery. This study was designed to evaluate the antibacterial and anti-oxidant activities of different concentrations of laurel essential oil (0.5%, 1%, 1.5%) against two bacterial strains "Staphylococcus aureus as food poisoning bacteria and Pseudomonas fluorescence as food spoilage bacteria" in order to enhance fish safety and increase shelf life. A total of 80 samples of freshly dead Oreochromis niloticus fish were collected after experimental infection with the two bacterial strains followed by treatment with different concentrations of laurel essential at different storage time at chilling temperature. The results showed that laurel essential oil was efficient against the tested bacteria, but varied in its antibacterial activity as follows; the highest reduction percent of S. aureus and P. fluorescence at rate of 99.97% and 94.5% was detected 6 days after laurel oil treatment, respectively, and reached 100% 9 day after oil treatment at the same concentration. While the lowest value was obtained with 0.5% concentration. Laurel oil (1.5%) also showed a significant decrease in pH, TNB-N and TBA. Based on the obtained data, it could be concluded that, laurel essential oil has strong antibacterial and antioxidant activity against the tested bacteria, so that it can be used as natural food preservatives alternatives to other synthetic agents to keep quality and increase fish shelf life.Key words: Laurus nobilis; essential oil; antibacterial activity; fish shelf-life; food safety