Anti-Salmonella Activity of Thymus serpyllum Essential Oil in Sous Vide Cook-Chill Rabbit Meat.

Food is generally prepared and vacuum-sealed in a water bath, then heated to a precise temperature and circulated in a sous vide machine. Due to its affordability and ease of use, this cooking method is becoming increasingly popular in homes and food service businesses. However, suggestions from manufacturers and chefs for long-term, low-temperature sous vide cooking raise questions about food safety in the media. In this study, heat treatment with different times and wild thyme essential oil (EO) in sous vide-processed rabbit longissimus dorsi muscle were found to inactivate Salmonella enterica. The rabbit meat samples were vacuum-packed in control groups, in the second group the rabbit meat samples were injected with S. enterica, and in the third group were meat samples infected with S. enterica with Thymus serpylum EO additive. The vacuum-packed samples were cooked sous vide for the prescribed time at 55, 60, and 65 °C. At 5, 15, 30, and 60 min, the quantities of S. enterica, total bacterial counts, and coliform bacteria were measured in groups of sous vide rabbit meat. Microbiological analyses of rabbit meat samples on days 1 and 7 were evaluated. In this study, total viable counts, coliforms bacteria, and number of Salmonella spp. were identified. After incubation, isolates from different groups of microorganisms were identified by the mass spectrometry technique. For each day measured, the test group exposed to a temperature of 55 °C for 5 min had a greater number of total microbiota. The most isolated microorganisms by MALDI-TOF MS Biotyper from the control and treated groups were Lactococcus garvieae and in the treated groups also S. enterica. Based on our analysis of sous vide rabbit meat samples, we discovered that adding 1% of thyme essential oil to the mixture reduced the amount of Salmonella cells and increased the overall and coliform bacterial counts. The microbiological quality of sous vide rabbit meat that was kept for seven days was positively impacted by the addition of thyme essential oil.

Thymus zygis, Valuable Antimicrobial (In Vitro and In Situ) and Antibiofilm Agent with Potential Antiproliferative Effects.

With the growing issues of food spoilage, microbial resistance, and high mortality caused by cancer, the aim of this study was to evaluate T. zygis essential oil (TZEO) as a potential solution for these challenges. Here, we first performed GC/MS analysis which showed that the tested TZEO belongs to the linalool chemotype since the abundance of linalool was found to be 38.0%. Antioxidant activity assays showed the superiority of TZEO in neutralizing the ABTS radical cation compared to the DPPH radical. The TZEO was able to neutralize 50% of ABTS•+ at the concentration of 53.03 ± 1.34 µg/mL. Antimicrobial assessment performed by employing disc diffusion and minimal inhibitory concentration assays revealed TZEO as a potent antimicrobial agent with the highest inhibition activity towards tested gram-negative strains. The most sensitive on the treatment with TZEO was Enterobacter aerogenes showing an MIC 50 value of 0.147 ± 0.006 mg/mL and a MIC 90 value of 0.158 ± 0.024 mg/mL. Additionally, an in situ analysis showed great effects of TZEO in inhibiting gram-negative E. coli, P. putida, and E. aerogenes growing on bananas and cucumbers. Treatment with the TZEO vapor phase in the concentration of 500 µg/mL was able to reduce the growth of these bacteria on the food models to the extent > 90%, except for E. coli growth on the cucumber, which was reduced to the extent of 83.87 ± 4.76%. Furthermore, a test on the antibiofilm activity of the tested essential oil revealed its biofilm prevention effects against Salmonella enterica which forms biofilms on plastic and stainless-steel surfaces. Performed tests on the TZEO effects towards cell viability showed no effects on the normal MRC-5 cell line. However, the results of MTT assay of TZEO effects on three cancer cell lines (MDA-MB-231, HCT-116, and K562) suggest that TZEO exerted the strongest effects on the inhibition of the viability of MDA-MB-231 cells, especially after long-term treatment in the highest concentration applied with reducing the viability of the cells to 57%. Additionally, results of NBT and Griess assays suggest that TZEO could be a convenient candidate for future testing for developing novel antitumor therapies.

Chemical Composition and Biological Activities of Eucalyptus globulus Essential Oil.

Eucalyptus globulus essential oil (EGEO) is considered as a potential source of bioactive compounds with significant biological activity. The aim of this study was to analyze the chemical composition of EGEO, in vitro and in situ antimicrobial activity, antibiofilm activity, antioxidant activity, and insecticidal activity. The chemical composition was identified using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). The main components of EGEO were 1,8-cineole (63.1%), p-cimene (7.7%), a-pinene (7.3%), and a-limonene (6.9%). Up to 99.2% of monoterpenes were present. The antioxidant potential of essential oil and results indicate that 10 µL of this sample can neutralize 55.44 ± 0.99% of ABTS•+, which is equivalent to 3.22 ± 0.01 TEAC. Antimicrobial activity was determined via two methods: disk diffusion and minimum inhibitory concentration. The best antimicrobial activity was shown against C. albicans (14.00 ± 1.00 mm) and microscopic fungi (11.00 ± 0.00 mm-12.33 ± 0.58 mm). The minimum inhibitory concentration showed the best results against C. tropicalis (MIC 50 2.93 µL/mL, MIC 90 3.17 µL/mL). The antibiofilm activity of EGEO against biofilm-forming P. flourescens was also confirmed in this study. The antimicrobial activity in situ, i.e., in the vapor phase, was significantly stronger than in the contact application. Insecticidal activity was also tested and at concentrations of 100%, 50%, and 25%; the EGEO killed 100% of O. lavaterae individuals. EGEO was comprehensively investigated in this study and information regarding the biological activities and chemical composition of the essential oil of Eucalyptus globulus was expanded.

Biological Activity of Cupressus sempervirens Essential Oil.

The aim of this study was to evaluate the antioxidant, antibiofilm, antimicrobial (in situ and in vitro), insecticidal, and antiproliferative activity of Cupressus sempervirens essential oil (CSEO) obtained from the plant leaf. The identification of the constituents contained in CSEO was also intended by using GC and GC/MS analysis. The chemical composition revealed that this sample was dominated by monoterpene hydrocarbons α-pinene, and δ-3-carene. Free radical scavenging ability, performed by using DPPH and ABTS assays, was evaluated as strong. Higher antibacterial efficacy was demonstrated for the agar diffusion method compared to the disk diffusion method. The antifungal activity of CSEO was moderate. When the minimum inhibitory concentrations of filamentous microscopic fungi were determined, we observed the efficacy depending on the concentration used, except for B. cinerea where the efficacy of lower concentration was more pronounced. The vapor phase effect was more pronounced at lower concentrations in most cases. Antibiofilm effect against Salmonella enterica was demonstrated. The relatively strong insecticidal activity was demonstrated with an LC50 value of 21.07% and an LC90 value of 78.21%, making CSEO potentially adequate in the control of agricultural insect pests. Results of cell viability testing showed no effects on the normal MRC-5 cell line, and antiproliferative effects towards MDA-MB-231, HCT-116, JEG-3, and K562 cells, whereas K562 cells were the most sensitive. Based on our results, CSEO could be a suitable alternative against different types of microorganisms as well as suitable for the control of biofilms. Due to its insecticidal properties, it could be used in the control of agricultural insect pests.

Salvia sclarea Essential Oil Chemical Composition and Biological Activities.

Salvia sclarea essential oil (SSEO) has a long tradition in the food, cosmetic, and perfume industries. The present study aimed to analyze the chemical composition of SSEO, its antioxidant activity, antimicrobial activity in vitro and in situ, antibiofilm, and insecticidal activity. Besides that, in this study, we have evaluated the antimicrobial activity of SSEO constituent (E)-caryophyllene and standard antibiotic meropenem. Identification of volatile constituents was performed by using gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS) techniques. Results obtained indicated that the main constituents of SSEO were linalool acetate (49.1%) and linalool (20.6%), followed by (E)-caryophyllene (5.1%), p-cimene (4.9%), a-terpineol (4.9%), and geranyl acetate (4.4%). Antioxidant activity was determined as low by the means of neutralization of the DDPH radical and ABTS radical cation. The SSEO was able to neutralize the DPPH radical to an extent of 11.76 ± 1.34%, while its ability to decolorize the ABTS radical cation was determined at 29.70 ± 1.45%. Preliminary results of antimicrobial activity were obtained with the disc diffusion method, while further results were obtained by broth microdilution and the vapor phase method. Overall, the results of antimicrobial testing of SSEO, (E)-caryophyllene, and meropenem, were moderate. However, the lowest MIC values, determined in the range of 0.22-0.75 µg/mL for MIC50 and 0.39-0.89 µg/mL for MIC90, were observed for (E)-caryophyllene. The antimicrobial activity of the vapor phase of SSEO (towards microorganisms growing on potato) was significantly stronger than that of the contact application. Biofilm analysis using the MALDI TOF MS Biotyper showed changes in the protein profile of Pseudomonas fluorescens that showed the efficiency of SSEO in inhibiting biofilm formation on stainless-steel and plastic surfaces. The insecticidal potential of SSEO against Oxycarenus lavatera was also demonstrated, and results show that the highest concentration was the most effective, showing insecticidal activity of 66.66%. The results obtained in this study indicate the potential application of SSEO as a biofilm control agent, in the shelf-life extension and storage of potatoes, and as an insecticidal agent.

An In-Depth Study on the Chemical Composition and Biological Effects of Pelargonium graveolens Essential Oil.

The essential oil of Pelargonium graveolens (PGEO) is identified in the literature as a rich source of bioactive compounds with a high level of biological activity. This study aimed to examine the chemical profile of PGEO as well as its antioxidant, antibacterial, antibiofilm, and insecticidal properties. Its chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS), achieving comprehensive identification of 99.2% of volatile compounds. The predominant identified compounds were ß-citronellol (29.7%) and geraniol (14.6%). PGEO's antioxidant potential was determined by means of DPPH radical and ABTS radical cation neutralization. The results indicate a higher capacity of PGEO to neutralize the ABTS radical cation, with an IC50 value of 0.26 ± 0.02 mg/mL. Two techniques were used to assess antimicrobial activity: minimum inhibitory concentration (MIC) and disk diffusion. Antimicrobial evaluation using the disk diffusion method revealed that Salmonella enterica (14.33 ± 0.58 mm), which forms biofilms, and Priestia megaterium (14.67 ± 0.58 mm) were most susceptible to exposure to PGEO. The MIC assay demonstrated the highest performance of this EO against biofilm-forming S. enterica (MIC 50 0.57 ± 0.006; MIC 90 0.169 ± 0.08 mg/mL). In contrast to contact application, the assessment of the in situ vapor phase antibacterial activity of PGEO revealed significantly more potent effects. An analysis of antibiofilm activity using MALDI-TOF MS demonstrated PGEO's capacity to disrupt the biofilm homeostasis of S. enterica growing on plastic and stainless steel. Additionally, insecticidal evaluations indicated that treatment with PGEO at doses of 100% and 50% resulted in the complete mortality of all Harmonia axyridis individuals.

Microbiological and Physicochemical Composition of Various Types of Homemade Kombucha Beverages Using Alternative Kinds of Sugars.

Kombucha is a beverage made by fermenting sweetened tea with a symbiotic culture of yeast and bacteria. Literature data indicate that the kombucha beverage shows many health-promoting properties such as detoxification, chemo-preventive, antioxidant, antimicrobial, antifungal, and general strengthening. The research conducted focuses on the analysis of polyphenolic compounds formed in the fermentation process using ultra-efficient liquid chromatography, as well as on checking the antimicrobial properties of kombucha against pathogenic bacteria and yeasts found in food. Analysis of the composition of the tea mushroom (SCOBY) microflora using the MALDI TOF MS Biotyper mass spectrometer showed 8 species of bacteria and 7 species of yeasts. In vitro studies confirm the bactericidal and bacteriostatic properties of fermented kombucha beverages, with white and green tea beverages showing the highest antibacterial activity. The bacteria Staphylococcus aureus and yeast Candida albicans were the most sensitive to the effects of kombucha tea beverages. UPLC chromatographic analysis confirmed the presence of 17 bioactive compounds in kombucha beverages that can affect human health. The analyses conducted were aimed at indicating the best recipe and conditions to prepare a kombucha beverage, which allowed the selection of the version with the best health-promoting properties. Fermented kombucha teas contain many elements such as aluminium, calcium, iron, potassium, magnesium, sodium, phosphorus, and sulphur.

Assessment of Ocimum basilicum Essential Oil Anti-Insect Activity and Antimicrobial Protection in Fruit and Vegetable Quality.

Basil (Ocimum basilicum) is a commonly used herb; it also contains essential oils and other valuable compounds. The basil oil obtained has a pleasant aroma, but also a broad spectrum of biological activity. This work reports on the chemical composition, antioxidant, antimicrobial and anti-insect activity in vitro and in situ of Ocimum basilicum essential oil (OBEO) obtained by steam distillation of fresh flowering plants. Gas chromatography-mass spectrometry, DPPH, agar and disc diffusion and vapor phase methods were used to analyze the OBEO properties. The analysis of the chemical composition of OBEO showed that its main components were methyl chavicol (88.6%), 1,8-cineole (4.2%) and α-trans-bergamotene (1.7%). A strong antioxidant effect was demonstrated at the level of 77.3%. The analysis of antimicrobial properties showed that OBEO exerts variable strength of inhibiting activity against various groups of microorganisms. The growth inhibition zones ranged from 9.67 to 15.33 mm in Gram-positive (G+) and Gram-negative (G-) bacteria and from 5.33 to 7.33 mm in yeast. The lowest measured minimal inhibition concentration (MIC) was 3.21 µL/mL against Gram-negative Azotobacter chrococcum and Gram-positive Micrococcus luteus. The antimicrobial activity of in situ vapor phase of OBEO was also confirmed on apples, pears, potatoes and kohlrabi. The highest insecticidal activity against Pyrrhocorisapterus, observed at the concentration of 100%, caused the death of 80% of individuals. Due to its broad spectrum of activity, OBEO seems an ideal candidate for preserving fruit and vegetables.

Combined Effect of Vacuum Packaging, Fennel and Savory Essential Oil Treatment on the Quality of Chicken Thighs.

The aim of the present work was to evaluate the microbiological quality of chicken thighs after treatment by fennel (Foeniculum vulgare) and savory (Satureja hortensis) essential oil, stored under vacuum packaging (VP) at 4 ± 0.5 °C for a period of 16 days. The following treatments of chicken thighs were used: Air-packaging control samples (APCS), vacuum-packaging control samples (VPC), vacuum-packaging (VP) control samples with rapeseed oil (VPRO), VP (vacuum-packaging) with fennel essential oil at concentrations 0.2% v/w (VP + F), and VP with savory essential oil at concentration 0.2% v/w (VP + S). The quality assessment of APCS, VPC, VPRO, VP + F and VP + S products was established by microbiological analysis. The microbiological parameters as the total viable counts of bacteria of the Enterobacteriaceae family, lactic acid bacteria (LAB), and Pseudomonas spp. were detected. Bacterial species were identified with the MALDI-TOF MS Biotyper. The combination of essential oils and vacuum packaging had a significant effect (p < 0.05) on the reduction of total viable counts (TVC) compared with control group without vacuum packaging and the untreated control group. Though 15 genera and 46 species were isolated with scores higher than 2.3 from the chicken samples.

The antioxidant and antimicrobial activity of essential oils against Pseudomonas spp. isolated from fish.

Natural products of plant origin, which include essential oils (EO) could be used as a growth inhibitor of pathogenic and spoilage microflora in food. The objective of this study was to determine the antibacterial and antioxidant activity of 21 EO against 10 Pseudomonas species isolated from freshwater fish. The chemical composition of EO was determined by gas chromatography/mass spectrometry. The disc diffusion method and detection of minimum inhibitory concentration (MIC) were used for the determination of the antimicrobial activity. All the EO tested exhibited antimicrobial activity, however, Cinnamomum zeylanicum EO was the most effective against Pseudomonas spp. both according to the disc diffusion and MIC methods. The EOs of Cymbopogon nardus, Origanum vulgare, Foeniculum vulgare and Thymus serpyllum showed the highest antioxidant activity of 93.86 µg, 83.47 µg, 76.74 µg and 74.28 µg TEAC/mL. Application of EO could be an effective tool for inhibition of growth of Pseudomonas spp. on fish.