Antimicrobial activity of Pistacia lentiscus and Satureja montana essential oils against Listeria monocytogenes CECT 935 using laboratory media: Efficacy and synergistic potential in minced beef

Bio-functional properties of Jilungin (Terminalia canescens)

Jilungin (Terminalia canescens) is a native Australian plant and the Indigenous "Nyul Nyul" people of the  Kimberley region of Western Australia use its leaves to make herbal tea. Due to the rise in the popularity of drinking Jilungin tea among the consumers in Australia and internationally, it is important to study the nutritional and health-beneficial properties as well as safety of Jilungin leaves. This study aims to determine the nutritional composition, anti-nutritional factors, antimicrobial and antidiabetic properties of Jilungin leaves. Also, the phytochemical profiling using UHPLC-MS/MS (Ultra-performance liquid chromatographymass spectrometry) and antioxidant activity of Jilungin methanolic extracts and herbal infusion were investigated. The safety of the leaves and infusion was also investigated by using in vitro mammalian cell lines (Caco2, HT29, and HepG2) through cell viability assays. The leaves are rich in dietary fiber (43.9%) and linoleic acid (30.4% of total fatty acids). Phytochemical profiling revealed ellagic acid, geraniin, pedunculagin, and punicalagin as the major bioactive compounds. The results also demonstrated that Jilungin has strong antioxidant and antidiabetic activities. A significant (p < 0.01) strong positive correlation was observed between the high antioxidant activity of Jilungin infusion with the major bioactive compounds. Jilungin extracts (50 mg/mL) exhibited strong antimicrobial activity against Staphylococcus aureus and Bacillus cereus. Its infusion and methanolic extract were safe on the studied cell lines (Caco-2, HT29, and HepG2) at higher concentrations of 66.6 and 98 mg/mL, respectively. Therefore, Jilungin teas or infusions could be a safe and effective way to promote health and well-being. PRACTICAL APPLICATION: Jilungin tea is very popular among consumers in Australia and is gaining popularity worldwide. The current study will increase knowledge on the nutritional aspects and safety of the Jilungin use.

Rosmarinus officinalis essential oils' eradication of beta-lactamase and multidrug resistant clinical bacterial pathogens from hospital settings

Antibiotics have become increasingly ineffective in the face of bacterial resistance, particularly in hospitals. Interestingly, there is high demand for bioprospecting of secondary metabolites, particularly for treating multidrug-resistant clinical diseases. In fact, Rosemary has been used for its antiseptic properties dating back to antiquity. The aim of this research is to evaluate the effectiveness of Rosmarinus officinalis essential oil against multidrug-resistant clinical bacterial pathogens. Results showed promising antibacterial activity against seven bacteria: Escherichia coli, Enterobacter cloacae, Staphylococcus aureus, Serratia odorifera, Klebsiella pneumoniae, Klebsiella oxytoca, Aeromonas hydrophila with MIC values of 35.7, 17.85, 71.4, 8.9, 17.8, 285.7, 35.7 µg/ml respectively and MBC values of 142.8, 71.4, 285.7, 35.7, 71.4, 571.5,71.4 µg/ml respectively. This study suggests that Rosmarinus essential oil can be used as a therapeutic agent in the fight against a wide range of multi-resistant bacteria.

Physicochemical, Antioxidant, and Antimicrobial Properties of Three Medicinal Plants from the Western Part of the Rhodope Mountains, Bulgaria

The present study examined the physicochemical, antioxidant, and antimicrobial properties of three medicinal plants: thyme (Thymus callieri Borbás ex Velen), cotton thistle (Onopordum acanthium L.), and hawthorn fruit (Crataegus monogyna Jacq.) from the Western Rhodope Mountains, Bulgaria. The first stage determined the physicochemical characteristics (moisture, ash, carbohydrates, proteins, and vitamin C) of the three herbs. The second stage investigated four types of extracts (aqueous, oil, methanolic, and ethanolic) of each herb and evaluated their total phenolic content, the presence of phenolic compounds (flavonoids and phenolic acids), their antioxidant activity, and antimicrobial properties. Thyme was characterised by the highest ash, protein, and vitamin C content (6.62%, 11.30%, and 571 mg/100 g, respectively). Hawthorn fruit showed the highest moisture and carbohydrate content (8.50% and 4.20%, respectively). The 70% ethanolic extracts of the three herbs exhibited the highest levels of phenolic compounds and, consequently, pronounced antioxidant activity, compared to the other three types of extracts. The aqueous, oil, methanolic, and ethanolic thyme extracts demonstrated the highest total phenolic content-TPC (27.20 mg GAE/g, 8.20 mg GAE/g, 31.70 mg GAE/g, and 310.00 mg GAE/g, respectively), compared to the extracts of the other two plants. These results were consistent with the highest antioxidant activity of the thyme extracts determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, the oxygen radical absorbance capacity (ORAC) assay, and the hydroxyl radical averting capacity (HORAC) assay (except for the oil extract examined using the DPPH method). The results from the high-performance liquid chromatography (HPLC) analysis revealed that the flavonoid quercetin-3-ß-glucoside had the highest concentration in thyme (374.5 mg/100 g), while myricetin dominated in the cotton thistle (152.3 mg/100 g). The phenolic acid content analysis showed prevalence of rosmaric acid in the thyme (995 mg/100 g), whereas chlorogenic acid was detected in the highest concentration in the cotton thistle and hawthorn fruit (324 mg/100 g and 27.7 mg/100 g, respectively). The aqueous, methanolic, and ethanolic extracts showed moderate to high antibacterial potential but limited antifungal activity. None of the oil extracts inhibited the test microorganisms used in the study.

Pistacia lentiscus essential oil and its pure active components as acaricides to control Dermanyssus gallinae (Acari: Mesostigmata)

The goal of this work was to assess the in vitro acaricidal effects of Pistacia lentiscus essential oil and its pure active components against red poultry mites Dermanyssus gallinae as an alternative to chemical acaricide (formamidines). Essential oil was obtained using hydrodistillation and then analyzed using GC-MS. The following major components were identified: α-pinene (20.58 %), D-Limonene (18.16 %), β-Myrcène (15.06 %), 4-Terpineol (7.68 %), caryophyllene (5.45 %) and γ-terpinene (5.21 %). The toxicity of essential oil and its six monoterpenes were tested at concentrations ranging from 0.43 to 3.50 mg/cm2, using contact and spraying bioassays. Toxicity was expressed as a lethal concentration (LC50 or LC90). The experiment results revealed that activity was method and concentration dependent, and the spraying method was more effective than the contact bioassay for acaricidal activity. In this bioassay, the highest mortality was observed with 4-Terpineol. The LC50 was estimated to be 0.184 mg/cm2 for this substance, followed by α-pinene, the LC50 of which was estimated to be 0.203 mg/cm2. Caryophyllene and γ-terpinene were found less effective in controlling D. gallinae. P. lentiscus oil and its major compounds were also evaluated for anti-acetylcholinesterase (AChE) effects; 4-Terpineol was found to be the most effective AChE inhibitor with IC50 values reaching 18.73 ± 2.83 µg/mL. This framework pointed out the importance of the traditional use of P. lentiscus as an ecofriendly alternative against ectoparasite of veterinary importance; D. gallinae. In vivo trials should also be conducted to assure the safe use of essential oils or individual compounds and to achieve efficient acaricidal property.

Use of Algerian Type Ras El-Hanout Spices Mixture with Marination to Increase the Sensorial Quality, Shelf Life, and Safety of Whole Rabbit Carcasses under Low-O2 Modified Atmosphere Packaging

This study aimed to evaluate the effect of combined treatments with Ras El-Hanout spices mixture and marinade solution containing extra virgin olive oil, onion, garlic, and concentrated lemon juice on sensorial quality, shelf life, and safety of whole rabbit carcasses under low-O2 modified atmosphere packaging (MAP). The values of pH, water holding capacity, shear force, thiobarbituric acid reactive substances, total volatile basic nitrogen, color (CIE L*a*b*), sensorial tests, and spoilage microorganisms were determined in rabbit meat at 0, 5, 10, 15, and 20 days during a retail display at 7 ± 1 °C. The results indicated that the marination process using the Ras El-Hanout blend of spices improved the water-holding capacity of meat maintaining optimum pH values. This combined treatment delayed the growth of major spoilage microorganisms, lipid oxidation, protein degradation, and undesirable color changes compared to unmarinated samples from the fifth to the twentieth day of retail exposure. The shelf life of rabbit carcasses under low-O2 MAP could be extended to 20 days of retail display, while rabbit carcasses under aerobic display presented a shorter shelf life of 5 to 10 days. Instrumental and sensorial tests showed that low-O2 MAP enhanced the tenderness of whole rabbit carcasses, with those marinated with Ras El-Hanout being the most positively perceived by the panelists. Marination also inhibited the pathogen Campylobacter jejuni, thus increasing the microbiological safety of the packaged product. The overall results indicated that low-O2 MAP combined with the Ras El-Hanout spice blend and marinade solution may represent a promising strategy for retail establishments to improve the quality, shelf life, and safety of rabbit carcasses.

Bioactive Properties of Kakadu Plum-Blended Products

Kakadu plum (Terminalia ferdinandiana), endemic to Australia, is growing in popularity due to its high levels of vitamin C and strong antioxidant properties. In this study, Kakadu plum fruit powder was used as a functional food ingredient with other plant materials to develop value-added products to enhance their nutritional and commercial value. The present study determined the bioactive properties of nine products, including three Kakadu plum fruit powder samples produced from different processing batches and five Kakadu plum-blended products. Vitamin C, the total phenolic content, and the ellagic acid content were determined. Bioactive properties such as antioxidant, antidiabetic, and antimicrobial assays were also performed. Cytotoxicity was tested to obtain more specific product information regarding food safety. Kakadu plum-blended products showed lower cytotoxicity and lower bioactive properties (antioxidant and antibacterial activities) in comparison to Kakadu plum powder. However, overall, most of the bioactive properties were shown to be higher in the blends when compared with the commercial blueberry powder as a benchmark antioxidant product. Therefore, there is great potential for Kakadu plum to contribute to the growing functional food and ingredient markets.

Valorisation of Three Underutilised Native Australian Plants: Phenolic and Organic Acid Profiles and In Vitro Antimicrobial Activity

Tasmannia lanceolata, Diploglottis bracteata and Syzygium aqueum are understudied native Australian plants. This study aimed to characterise the non-anthocyanin phenolic and organic acid profiles of the aqueous extracts obtained from the leaves of T. lanceolata and fruits of D. bracteata and S. aqueum by UHPLC-Q-Orbitrap-MS/MS and UHPLC-TQ-MS/MS. A total of 39, 22, and 27 non-anthocyanin polyphenols were tentatively identified in T. lanceolata, D. bracteata, and S. aqueum extracts, respectively. Furthermore, sugars and ascorbic acid contents as well as in vitro antioxidant and antimicrobial activities of the extracts were determined. Response surface methodology was applied to achieve an extract blend with a strong inhibitory effect against Pseudomonas viridiflava, the main cause of soft rot in vegetables, Bacillus subtilis, Rhodotorula diobovata and Alternaria alternata. The identified compounds including organic acids (e.g., quinic, citric and malic acids) and polyphenols (e.g., catechin, procyanidins, and ellagitannins) might contribute to the observed antimicrobial activity. Furthermore, this study provides the most comprehensive phenolic profiles of these three underutilised native Australian plants to date.

A Review of Regulatory Standards and Advances in Essential Oils as Antimicrobials in Foods

As essential oils (EOs) possess GRAS status, there is a strong interest in their application to food preservation. Trends in the food industry suggest consumers are drawn to environmentally friendly alternatives and less synthetic chemical preservatives. Although the use of EOs has increased over the years, adverse effects have limited their use. This review aims to address the regulatory standards for EO usage in food, techniques for delivery of EOs, essential oils commonly used to control pathogens and molds, and advances with new active compounds that overcome sensory effects for meat products, fresh fruits and vegetables, fruit and vegetable juices, seafood, dairy products, and other products. This review will show adverse sensory effects can be overcome in various products by the use of edible coatings containing encapsulated EOs to facilitate the controlled release of EOs. Depending on the method of cooking, the food product has been shown to mask flavors associated with EOs. In addition, using active packaging materials can decrease the diffusion rate of the EOs, thus controlling undesirable flavor characteristics while still preserving or prolonging the shelf life of food. The use of encapsulation in packaging film can control the release of volatile or active ingredients. Further, use of EOs in the vapor phase allows for contact indirectly, and use of nanoemulsion, coating, and film wrap allows for the controlled release of the EOs. Research has also shown that combining EOs can prevent adverse sensory effects. Essential oils continue to serve as a very beneficial way of controlling undesirable microorganisms in food systems.

Antibiotic properties of Satureja montana L. hydrolate in bacteria and fungus of clinical interest and its impact in non-target environmental microorganisms

The aim of this study was to analyse the microbicidal and microbiostatic activity of S. montana hydrolate L., the water-soluble fraction of the hydro-distillation process used to obtain the essential oil, on 14 Gram-positive and Gram-negative bacteria and a fungus of clinical interest. To consider whether this hydrolate is a more environmentally friendly alternative to traditional antibiotics, its effect on non-target microorganisms in the aquatic and terrestrial environment was analysed using natural soil and river microorganism communities, characterized through 16S rRNA gene sequencing. Results showed that S. montana hydrolate was especially effective (25% v/v concentration) against Pasteurella aerogenes, Streptococcus agalactiae and Acinetobacter baumannii (priority 1, WHO). It was also a microbicide for a further 7 bacterial strains and the fungus Candida albicans (50% v/v concentration). The river and soil communities exposed to the hydrolate showed a decrease in their growth, as well as a decrease in their ability to metabolize polymers and carbohydrates (soil microorganisms) and polymers, carboxylic and ketone acids (river microorganisms). Hydrolates could be an alternative to conventional antibiotics, but their impact on the environment must be taken into account.

Investigation of the effect of lavender (Lavandula angustifolia Mill.) essential oil on microbiological, physicochemical, and sensorial properties of meatballs during shelf-life, and its inhibitory effect on Escherichia coli O157:H7

The present work aimed at investigating the effect of lavender (Lavandula angustifolia Mill.) essential oil on the microbiological, physicochemical, and sensorial properties of meatballs, and elucidating its antimicrobial effect on the meatballs contaminated with Escherichia coli O157:H7. The essential oil as determined via gas chromatography mass spectrometry (GC-MS) contained two major components, linalool and linalyl acetate, at 37.023 and 28.651%, respectively. The antioxidant activity test which was performed via 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity test, revealed that the essential oil had moderate capacity. The antibacterial activity of the essential oil was investigated against E. coli O157:H7, and the minimum inhibition concentration (MIC) was determined to be 6.4 μL/mL. Six different test groups were formed based on the concentrations of E. coli O157:H7 (0 and 108 CFU/mL) and essential oil (0, 6.4, and 12.8 μL/mL). Although essential oil had inhibitory effect against TAMB, coliforms, yeasts and moulds, Staphylococcus aureus, E. coli, and especially E. coli O157:H7 in the microbiological analyses, no effect was observed on the physicochemical properties of the meatballs. Approximately, 3 log decrease was observed in the E. coli O157:H7 levels when essential oil was added at a concentration of two-fold MIC value. It was observed that the addition of essential oil to meatballs did not increase the lipid oxidation level as much as the control group. Meatballs that contained essential oil at MIC value achieved the highest general acceptability scores at the end of their storage periods.

Lipophilic Compounds and Antibacterial Activity of Opuntia ficus-indica Root Extracts from Algeria

The chemical composition, investigated by gas chromatography-mass spectrometry, and antibacterial activity of lipophilic extractives of three varieties of Opuntia ficus-indica roots from Algeria are reported in this paper for the first time. The results obtained revealed a total of 55 compounds, including fatty acids, sterols, monoglycerides and long chain aliphatic alcohols that were identified and quantified. β-Sitosterol was found as the major compound of the roots of the three varieties. Furthermore, considerable amounts of essential fatty acids (ω3, ω6, and ω9) such as oleic, linoleic, and linolenic acids were also identified. The green variety was the richest among the three studied varieties. The antibacterial activity, evaluated with disc diffusion method, revealed that lipophilic extracts were effective mainly against Gram-positive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) (19~23 mm). Gram-negative strains mainly Pseudomonas aeruginosa gave an inhibition zone of 18 mm, which is considered high antibacterial activity. The minimal inhibitory concentrations of the tested bacteria revealed interesting values against the majority of bacteria tested: 75–100 µg mL⁻¹ for Bacillus sp., 250–350 µg/mL for the two Staphylococcus strains, 550–600 µg mL⁻¹ for E. coli, and 750–950 µg mL⁻¹ obtained with Pseudomonas sp. This study allows us to conclude that the lipophilic fractions of cactus roots possess interesting phytochemicals such as steroids, some fatty acids and long chain alcohols that acted as antibiotic-like compounds countering pathogenic strains.

Xanthine Oxidase Inhibitory Activity and Chemical Composition of Pistacia chinensis Leaf Essential Oil

Gout is a common metabolic disease caused by abnormal purine metabolism that promotes the formation and deposition of monosodium urate crystals within joints that causes acute arthritis and can seriously affect the daily life of patients. Pistacia chinensis is one of the traditional medicinal plants of the Anacardiaceae family, and there have been many studies on its biological activity, including anti-inflammatory, antidepressant, antibacterial, antioxidant, and hypoglycemic activities. The aim of this study was to evaluate the antigout effect of P. chinensis leaf essential oil and its constituents through xanthine oxidase inhibition. Leaf essential oil showed good xanthine oxidase inhibitory activity for both substrates, hypoxanthine and xanthine. Six fractions were obtained from open column chromatography, and fraction E1 exhibited the best activity. The constituents of leaf essential oil and fraction E1 were analyzed by GC-MS. The main constituents of both leaf essential oil and fraction E1 were limonene and 3-carene; limonene showed a higher inhibitory effect on xanthine oxidase. Based on the enzyme kinetic investigation, limonene was the mixed-type inhibitor against xanthine oxidase. The results revealed that Pistacia chinensis leaf essential oil and limonene have the potential to act as natural remedies for the treatment of gout.

Characterization and Antifungal Activity of Pullulan Edible Films Enriched with Propolis Extract for Active Packaging

Active pullulan films with the addition of 3, 5 or 10% propolis extract produced by the casting method were tested in the study. Propolis extracts from Bochnia County, Siedlce County and Ełk County (Poland) were used. The appearance of the films was characterized, as well as physical parameters (thickness, moisture content, water solubility), tensile strength (TS), elongation at break (EB), optical characteristics (light transparency, UV barrier, color) and antifungal properties. The antifungal activity of the films was tested by the disc diffusion method against yeast (Candida albicans, C. krusei, Saccharomyces cerevisiae, Rhodotorula mucilaginosa) and mold (Alternaria solani, Fusarium solani, Rhizopus stolonifer, Colletotrichum gloeosporioides, C. cladosporioides, Aspergillus niger, A. ochraceus, Mucor mucedo, Penicillium expansum, P. chrysogenum). The origin of propolis influenced the color and water solubility of the films. The addition of increasing concentrations of propolis extract increased the film thickness and the intensity of the yellow color, extended the water dissolution time of the film and reduced the values of TS and EB. The addition of propolis extract in the pullulan film improved UV radiation protection but decreased light transparency. The antifungal activity increased significantly with the increasing concentration of propolis extract in the film, regardless of the origin of propolis. Molds showed greater sensitivity to pullulan films containing propolis extract than yeasts. In general, films made of pullulan with the addition of propolis extract can be considered as natural active packaging to protect against the growth of fungi in food.

Profiling of Essential Oils from the Leaves of Pistacia lentiscus Collected in the Algerian Region of Tizi-Ouzou: Evidence of Chemical Variations Associated with Climatic Contrasts between Littoral and Mountain Samples

Leaves of Pistacia lentiscus were collected from two Algerian sites in the mountains and the littoral of the Tizi-Ouzou region. The harvest was conducted in four consecutive seasons on the same selected set of trees. Essential oils (EOs) were extracted by hydrodistillation; then, they were analyzed by gas chromatography coupled mass spectrometry (GC-MS). Forty-seven constituents could be detected and quantified, including α-pinene (2–13%), β-caryophyllene (8–25%), β-myrcene (0.3–19%), bornyl acetate (0.8–7%), δ-cadinene (3–8%), bisabolol (1–9%), β-pinene (0.9–7%), caryophyllene oxide (4–9%), and α-cadinol (3–11%). Antioxidant (AOx) activities of the EOs were assessed by ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and 2,2′-azino-bis (3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) assays. Significant differences in EO composition and AOx activities appeared dependent on the season and the site. Variations of AOx activities were significant for the FRAP and ABTS tests but not for DPPH. Characterization of the leaf fatty acyl (FA) profiles was performed by GC-MS. Variability appeared according to season and altitude. Polyunsaturated fatty acids levels were high (27–55%) at the coldest date and place. The levels of linolenic acyl in the leaves were significantly correlated with bisabolol levels in the EOs (Spearman’s correlation coefficient: 0.818). Such results will be useful for the sustainable local valorization of wild P. lentiscus. These data also open new routes for further studies on terpenoid biosynthesis using correlation networks and fluxomic approaches.

Unani medicinal herbs as potential air disinfectants: an evidence-based review

OBJECTIVES

Indoor air quality has a significant impact on our health and quality of life, as people spends 80-90% of their time indoors. Fumigation of several medicinal herbs has been recommended by Unani scholars to improve air quality, but their efficacy in air purification is still unknown. Hence, this article aims to discuss the applicability of proposed medicinal herbs in the light of current researches.

METHODS

A manual literature survey of classical Unani texts was conducted to collect information about the herbs recommended for air purification. In addition, research databases such as PubMed, Google Scholar, and ScienceDirect were extensively searched for evidence on the efficacy and mechanism of action of the suggested herbs in air purification.

RESULTS

In classical Unani texts, authors have found descriptions of 26 herbs that have been recommended for improving air quality. In-vitro studies have confirmed the antimicrobial activity of 19 of these herbs. Moreover, the efficacy of Styrax benzoin, Commiphora myrrha and Acorus calamus fumigation on aerial microbes have also been validated by studies.

CONCLUSIONS

The findings of the literature review clearly demonstrated that the herbs recommended by Unani scholars for air purification have broad-spectrum antimicrobial activity, indicating that these herbs could be a potential candidate for air disinfectant. Therefore, authors recommend the further researches on proposed herbs to validate their efficiency against airborne pathogens in the vapour phase.

Food Ingredients Derived from Lemongrass Byproduct Hydrodistillation: Essential Oil, Hydrolate, and Decoction

Essential oil (EO), hydrolate, and nondistilled aqueous phase (decoction) obtained from the hydrodistillation of lemongrass byproducts were studied in terms of their potential as food ingredients under a circular economy. The EO (0.21%, dry weight basis) was composed mainly of monoterpenoids (61%), the majority being citral (1.09 g/kg). The minimal inhibitory concentrations (MIC) of lemongrass EO against Escherichia coli, Salmonella enterica, and Staphylococcus aureus, were 617, 1550, and 250 μg/mL, respectively. This effect was dependent on the citral content. Particularly for Gram-negative bacteria, a synergism between citral and the remaining EO compounds enhanced the antimicrobial activity. The polymeric material obtained from the nondistilled aqueous phase was composed of phenolic compounds (25% gallic acid equivalents) and carbohydrates (22%), mainly glucose (66 mol%). This polymeric material showed high antioxidant activity due to bound phenolic compounds, allowing its application as a functional dietary fiber ingredient. Matcha green tea formulations were successfully mixed with lemongrass hydrolate containing 0.21% EO (dry weight basis) with 58% of monoterpenoids, being citral at 0.73 g/kg, minimizing matcha astringency with a citrus flavor and extending the product shelf life. This holistic approach to essential oils’ hydrodistillation of Cymbopogon citratus byproducts allows for valorizing of the essential oil, hydrolate, and decoction for use as food ingredients.

Plant Extracts for the Control of Listeria monocytogenes in Meat Products

The antimicrobial activity of garlic (Allium sativum L.) and onion (Allium cepa L.) plant active extracts was determined against Listeria monocytogenes in two meat products. Samples of sausages “cacciatore” and cooked ham in vacuum-packaged slices were artificially contaminated, and the presence of Listeria was evaluated during the sausages ripening and throughout the shelf-life of the cooked ham. The test carried out on sausages did not show differences among treated and untreated samples. The antagonistic activity of the plant extracts against the pathogen was probably hidden by the competition from the sausages microbial flora and the pH and the water activity (aw) decrease. On the other hand, the plant extracts determined an initial reduction of about 1.00 log cfu/g of the L. monocytogenes viable count in the cooked ham slices contaminated with 103 cfu/g, but the best result was obtained with the contamination of 102 cfu/g of L. monocytogenes. In addition to the pathogen’s initial decrease, we observed an extension of the lag phase and a reduction of the Listeria growth rate. Considering that the presence of L. monocytogenes during the slicing phase of the cooked ham does not exceed 10 cfu/g, the use of plant extracts can lead to complete pathogen elimination.

Essential oils as natural antimicrobials applied in meat and meat products-a review

Meat and meat products are highly susceptible to the growth of micro-organism and foodborne pathogens that leads to severe economic loss and health hazards. High consumption and a considerable waste of meat and meat products result in the demand for safe and efficient preservation methods. Instead of synthetic additives, the use of natural preservative materials represents an interest. Essential oils (EOs), as the all-natural and green-label trend attributing to remarkable biological potency, have been adopted for controlling the safety and quality of meat products. Some EOs, such as thyme, cinnamon, rosemary, and garlic, showed a strong antimicrobial activity individually and in combination. To eliminate or reduce the organoleptic defects of EOs in practical application, EOs encapsulation in wall materials can improve the stability and antimicrobial ability of EOs in meat products. In this review, meat deteriorations, antimicrobial capacity (components, effectiveness, and interactions), and mechanisms of EOs are reviewed, as well as the demonstration of using encapsulation for masking intense aroma and conducting control release is presented. The use of EOs individually or in combination and encapsulated applications of EOs in meat and meat products are also discussed.

The antimicrobial effect of thyme and rosemary essential oils against Listeria monocytogenes in sous vide turkey meat during storage

The research was aimed to study the impact of sous vide thermal treatment on the microbiological quality of fresh turkey breast meat after treatment with thyme and rosemary EOs and the survival of Listeria monocytogenes on the turkey meat samples. The samples were vacuum-packed and cooked at 55 °C, 60 °C, and 65 °C for 5, 15, 30 and, 60 min. There was an amount of 5 g (5 ±0.2 g) of the sample placed in PA/PE film bags and inoculated with 100 μL of L. monocytogenes inoculum. The sample was incubated at 37 °C for 18 h after bag sealing. The samples were tested on the 1st and 3rd days of experiments. The microbiological quality of fresh turkey breast meat was assessed by the detection of total microbial counts and meat microbiota was identified by mass spectrometry using MALDI-TOF MS Biotyper (Bruker Daltonics, Germany). Microbial counts differed significantly depending on temperature and time and the microbial counts ranged from 2.21 log cfu.g-1 to 8.26 log cfu.g-1 on the 1st and 3rd day of the experiment. The study shows that the sous vide method with essential oils combination is an effective method and it can be used to protect the microbiota of turkey meat and L. monocytogens survival, however, the quality of raw material is crucial.

Essential Oils and Their Application in Food Safety

Food industries are facing a great challenge due to contamination of food products with different microbes such as bacteria, fungi, viruses, parasites, etc. These microbes deteriorate food items by producing different toxins during pre- and postharvest processing. Mycotoxins are one of the most potent and well-studied toxic food contaminants of fungal origin, causing a severe health hazard to humans. The application of synthetic chemicals as food preservatives poses a real scourge in the present scenario due to their bio-incompatibility, non-biodegradability, and environmental non-sustainability. Therefore, plant-based antimicrobials, including essential oils, have developed cumulative interest as a potential alternative to synthetic preservatives because of their ecofriendly nature and generally recognized as safe status. However, the practical utilization of essential oils as an efficient antimicrobial in the food industry is challenging due to their volatile nature, less solubility, and high instability. The recent application of different delivery strategies viz. nanoencapsulation, active packaging, and polymer-based coating effectively addressed these challenges and improved the bioefficacy and controlled release of essential oils. This article provides an overview of essential oils for the preservation of stored foods against bacteria, fungi, and mycotoxins, along with the specialized mechanism of action and technological advancement by using different delivery systems for their effective application in food and agricultural industries smart green preservative.

Leaves and Fruits Preparations of Pistacia lentiscus L.: A Review on the Ethnopharmacological Uses and Implications in Inflammation and Infection

There is an increasing interest in revisiting plants for drug discovery, proving scientifically their role as remedies. The aim of this review was to give an overview of the ethnopharmacological uses of Pistacia lentiscus L. (PlL) leaves and fruits, expanding the search for the scientific discovery of their chemistry, anti-inflammatory, antioxidative and antimicrobial activities. PlL is a wild-growing shrub rich in terpenoids and polyphenols, the oil and extracts of which have been widely used against inflammation and infections, and as wound healing agents. The more recurrent components in PlL essential oil (EO) are represented by α-pinene, terpinene, caryophyllene, limonene and myrcene, with high variability in concentration depending on the Mediterranean country. The anti-inflammatory activity of the oil mainly occurs due to the inhibition of pro-inflammatory cytokines and the arachidonic acid cascade. Interestingly, the capacity against COX-2 and LOX indicates PlL EO as a dual inhibitory compound. The high content of polyphenols enriching the extracts provide explanations for the known biological properties of the plant. The protective effect against reactive oxygen species is of wide interest. In particular, their anthocyanins content greatly clarifies their antioxidative capacity. Further, the antimicrobial activity of PlL oil and extracts includes the inhibition of Staphylococcus aureus, Escherichia coli, periodontal bacteria and Candida spp. In conclusion, the relevant scientific properties indicate PlL as a nutraceutical and also as a therapeutic agent against a wide range of diseases based on inflammation and infections.

Natural Phenolic Compounds for the Control of Oxidation, Bacterial Spoilage, and Foodborne Pathogens in Meat

Alternative technologies for long-term preservation, quality assurance, and safety of meat are continuously pursued by the food industry to satisfy the demands of modern consumers for nutritious and healthy meat-based products. Naturally occurring phenolic compounds are considered promising substances by the meat industry for their antioxidant and antimicrobial properties, while consumers seem to embrace them for their claimed health benefits. Despite the numerous in vitro and in situ studies demonstrating their beneficial effects against meat oxidation, spoilage, and foodborne pathogens, wide application and commercialization has not been yet achieved. Major obstacles are still the scarcity of legislative framework, the large variety of meat-based products and targeted pathogens, the limited number of case-specific application protocols and the questionable universal efficiency of the applied ones. The objectives of the present review are i) to summarize the current knowledge about the applications of naturally occurring phenols in meat and meat-based products, emphasizing the mechanisms, determinants, and spectrum of their antioxidant and antimicrobial activity; ii) to present state-of-the-art technologies utilized for the application of phenolic compounds in meat systems; and iii) to discuss relevant regulation, limitations, perspectives, and future challenges for their mass industrial use.

Garlic, Onion, and Cinnamon Essential Oil Anti-biofilms' Effect against Listeria monocytogenes

Biofilms represent a serious problem for food industries due to their persistence in processing surfaces, from which they can cause food spoilage or, even worse, lead to foodborne diseases. Microorganisms immersed in biofilms are more resistant to biocides. The search for natural effective alternatives for the prevention and the control of biofilms has increased lately. The aim of this research was to test the antibacterial and the anti-biofilm activities of cinnamon, onion, and garlic essential oils against Listeria monocytogenes. The methodology highlighted first the effect of these essential oils on L. monocytogenes using disc diffusion and minimum inhibitory concentration (MIC) methods and then on initial cell attachment and six hours preformed biofilms. The inhibition of biofilms was assessed by crystal violet assay. Sulfides were the most abundant compounds present in onion and garlic essential oils, while cinnamaldehyde was predominant in cinnamon essential oil. MIC values were of 0.025 mg mL-1 for onion essential oil and 0.100 mg mL-1 for cinnamon and garlic. Onion essential oil inhibited initial cell attachment by 77% at 0.5 of the MIC dose, while at MIC, cinnamon and garlic essential oils inhibited the initial microbial adhesion completely. All three essential oils completely inhibited initial cell attachment when applied at 2 MIC. On the contrary, preformed biofilms were more resistant, and the inhibition rate ranged from 33% to 78%. In summary, this investigation revealed that the essential oils of garlic, onion, and cinnamon show an effective antibiofilm activity against L. monocytogenes and are promising natural antimicrobial alternatives for food processing facilities.

GC-MS analysis and biological activity of hydroalcholic extracts and essential oils of Rhus typhina L. wood (anacardiaceae) in comparison with leaves and fruits

Hydroalcoholic extracts (HE) and essential oils (EO) of branches, leaves and fruits of Rhus typhina L., were characterized by GC-MS. HE (yealds: branches 68.30 mg/g, leaves 35.82 mg/g and fruits 257.76 mg/g), showed different compositions dominated by gallic acid (33.46%) in branches, its precursor 1-cyclohexane-3,4,5-hydroxy-carboxylic acid (20.55%) in leaves and malic acid (89.15%) in fruits. EO yields were 210 µg/g for branches (main component δ-cadinene, 22.00%), followed by fruits with 132 µg/g (β-pinene 32.2%) and by leaves with 54 µg/g and phenylacetaldehyde as major component (40.13%). Total phenolic content (TPC) was highest in branches HE (5.87 µg _GAE/mL) and in EO leaves (17.71 µg _GAE/mL). The highest value of radical scavenging activity (DPPH test) was detected in leaves HE and EO. The branches EO antimicrobial activity was strong against C. albicans and negligible against E. coli. Leaves and fruits EO showed strong activity against C. albicans and intermediate activity against Escherichia coli.

Antimicrobial activity of flavonoids from Sedum aizoon L. against Aeromonas in culture medium and in frozen pork

The chemical composition and antimicrobial activity of flavonoids from Sedum aizoon L. against Aeromonas in vitro were investigated, and the effect of flavonoid treatment on the quality of fresh pork during frozen storage for 6 months was also explored. The results showed that kaempferol, quercetin dihydrate, and catechin were the most predominant flavonoids from S. aizoon L. Flavonoids exhibited antibacterial activity to Aeromonas in vitro, which caused membrane damage, disruption of the bacterial surface, and internal ultrastructure, and resulted in the leakage of reducing sugars and proteins. Meanwhile, flavonoid treatment retarded the microbial growth and deteriorates of pork characteristics, including pH value, total volatile basic nitrogen (TVB-N), texture, and sensory evaluation during frozen storage, thereby prolonged the shelf life. Their results suggested that flavonoids from S. aizoon L. offer a promising choice for food safety and preservation.

Influence of stressing conditions caused by organic acids and salts on tolerance of Listeria monocytogenes to Origanum vulgare L. and Rosmarinus officinalis L. essential oils and damage in bacterial physiological functions

This study evaluated whether the pre-exposure (24, 48 and 72 h) to sublethal conditions caused by acetic acid (AA), lactic acid (LA), sodium chloride (NaCl) or potassium chloride (KCl) could induce increased cross-tolerance to the essential oils from Origanum vulgare L. (OVEO) and Rosmarinus officinalis L. (ROEO) in different Listeria monocytogenes strains. Damage to membrane integrity, membrane potential, enzymatic activity and efflux activity in L. monocytogenes cells pre-exposed (24 h) to AA or NaCl and further treated with OVEO or ROEO (8 and 24 h) were investigated using flow cytometry (FC). Results of minimum inhibitory concentration (MIC) modulation test showed that pre-exposure to sublethal conditions caused by organic acids or salts increased cross-tolerance only to ROEO, since MIC of ROEO increased up to 4.8-fold against pre-exposed cells. Otherwise, MIC of OVEO against these pre-exposed cells was up to ten-fold lower than that observed against not pre-exposed cells, indicating no increase in cross-tolerance. Bacterial survival assays showed that ROEO only decreased the counts over time of cells not pre-exposed to organic acids or salts, while OVEO decreased similarly or more the counts of pre-exposed cells compared to not pre-exposed cells. Results of FC analysis showed that all measured functions in L. monocytogenes cells pre-exposed to AA or NaCl and treated with OVEO or ROEO were affected, although with different intensities. These data indicate that exposure to sublethal conditions imposed by organic acids or salts could result in a phenotype of increased cross-tolerance to ROEO but not to OVEO in L. monocytogenes.

Assessment of Antioxidant and Antibacterial Properties on Meat Homogenates of Essential Oils Obtained from Four Thymus Species Achieved from Organic Growth

In the organic food industry, no chemical additives can be used to prevent microbial spoilage. As a consequence, the essential oils (EOs) obtained from organic aromatic herbs and spices are gaining interest for their potential as preservatives. The organic Thymus zygis, Thymus mastichina, Thymus capitatus and Thymus vulgaris EOs, which are common in Spain and widely used in the meat industry, could be used as antibacterial agents in food preservation. The aims of this study were to determine (i) the antibacterial activity using, as culture medium, extracts from meat homogenates (minced beef, cooked ham or dry-cured sausage); and (ii) the antioxidant properties of organic EOs obtained from T. zygis, T. mastichina, T. capitatus and T. vulgaris. The antioxidant activity was determined using different methodologies, such as Ferrous ion-chelating ability assay, Ferric reducing antioxidant power, ABTS radical cation (ABTS^•+) scavenging activity assay and 2,2′-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging method; while the antibacterial activity was determined against 10 bacteria using the agar diffusion method in different meat model media. All EOs analyzed, at all concentrations, showed antioxidant activity. T. capitatus and T. zygis EOs were the most active. The IC₅₀ values, for DPPH, ABTS and FIC assays were 0.60, 1.41 and 4.44 mg/mL, respectively, for T. capitatus whilst for T. zygis were 0.90, 2.07 and 4.95 mg/mL, respectively. Regarding antibacterial activity, T. zygis and T. capitatus EOs, in all culture media, had the highest inhibition halos against all tested bacteria. In general terms, the antibacterial activity of all EOs assayed was higher in the medium made with minced beef than with the medium elaborated with cooked ham or dry-cured sausage.

Listeria monocytogenes behaviour and quality attributes during sausage storage affected by sodium nitrite, sodium lactate and thyme essential oil

The effects of the addition of nitrite at 200 ppm (N), sodium lactate 1.5% (L) and thyme essential oil at 100 ppm (T1) on Listeria monocytogenes behaviour and ATPase activity inhibition were evaluated, as well as lipid oxidation through the quantification of malonaldehydes, in sausage stored at 8 ℃ for 41 days and at 30 ℃ for 14 days. The changes in the colour profile were performed during storage time at 8 ℃. Quantitative descriptive sensory analyses were performed after two days at 4 ℃. At 8 ℃, the treatments with the highest inhibition on L. monocytogenes were L and N, without significant differences. In turn, at 30 ℃, the bacterium was most inhibited with treatment L, followed by T1 and N, without significant differences. A 44.1% and 19% inhibition of ATPase activity was detected in L and T1 treatments, respectively. At 8 ℃ and 30 ℃, malonaldehydes content was not different between the treatments. N presented the highest values of a* and concentration of metmyoglobin after 41 days at 8 ℃. The panel detected differences between T1 and N for the aroma in the descriptors spices and herbal.

Influence of vacuum-ageing duration of whole beef on retail shelf life of steaks packaged with oregano (Origanum vulgare L.) active film under high O2

Beef Longissimus lumborum (LL) was no aged (LL0), aged for 7 days (LL7) and 14 days (LL14) under vacuum at 1 ± 1 °C. The obtained beefsteaks were packaged in high oxygen (Hi-O2) with active packaging (AP) during 13-21 days at 1 ± 1 °C. Redness (CIE a* values), metmyoglobin percentage (MetMb%), total flora (PCA), thiobarbituric acid-reactive substances (TBA-RS), instrumental tenderness (Warner-Bratzler shear force: WBSF), and sensory analyses were performed. The various variables differed amongst the ageing times and packaging systems (AP vs. control). Three and ten additional days of retail shelf life were observed for steaks from LL7 and LL14, respectively. AP increased efficiently the retail shelf life of beefsteaks, but did not affect meat tenderness. The extended ageing from 7 to 14 days also induced higher tenderness in beefsteaks and did not show any affect negative effect on other quality parameters. Innovative technology referring to ageing under vacuum combined with Hi-O2 MA/AP would be desirable for beefsteaks during display and constituted a good alternative for meat supermarkets.