Effect of Thymus vulgaris L. essential oil and thymol on the microbiological properties of meat and meat products: A review

Encapsulation of Thymol in Ethyl Cellulose-Based Microspheres and Evaluation of Its Sustained Release for Food Applications

Food waste is a global concern with enormous economic, environmental and social impacts that has contributed to active packaging evolution. However, incorporating bioactive substances into the packaging can deteriorate its physicochemical and mechanical characteristics. Thus, the objective of this work was to entrap the natural bioactive compound thymol into microparticles and apply them in the form of pads for the controlled release of bioactivity in food packaging material. The physicochemical characteristics and bioactivity of five different ethyl cellulose-based microparticles were evaluated. Increasing the amount of thymol in the formulation led to higher encapsulation efficiency. Encapsulation resulted in a substantial increase of >10-20 °C in the volatilization temperature of thymol, and the release of thymol occurred following a sustained profile, best described by the Higuchi release kinetic model. Increasing the polymer to thymol ratio in the microparticles resulted in higher thermal stability and a more gradual release profile. While all formulations demonstrated considerable inhibition of E. coli growth, the ones with the highest thymol content maintained their antimicrobial activity for at least one month of microparticle storage. Furthermore, the ability of the microparticles in retaining pH and titratable acidity of cherry tomatoes was evaluated, and it was confirmed that these characteristics were maintained during 21 days of storage.

Effect of Rheum ribes L. pulp enriched with eugenol or thymol on survival of foodborne pathogens and quality parameters of chicken breast fillets

The aim of this study was to characterize the pulp of Rheum ribes L. and to determine the effect of the pulp enriched with eugenol (1 %) or thymol (1 %) on the microbiological and physico-chemical quality of chicken breast fillets. Chicken breast fillets, inoculated with Listeria monocytogenes, Salmonella enterica subsp. enterica serovar Typhimurium, and Escherichia coli O157:H7 (~6.0 log10), were marinated for 24 h in a mixture prepared from a combination of Rheum ribes L. pulp with eugenol or thymol. The quality parameters were analyzed for 15 days at +4 °C. The Rheum ribes L. pulp was found to have high antioxidant activity, high total phenolic content and contained 22 different phenolic substances, among which rutin ranked first. The pulp contained high levels of p-xylene and o-xylene as volatile substances and citric acid as an organic acid. The combination of Pulp + Eugenol + Thymol (PET) reduced the number of pathogens in chicken breast fillets by 2.03 to 3.50 log10 on day 0 and by 2.25 to 4.21 log10 on day 15, compared to the control group (P < 0.05). The marinating treatment significantly lowered the pH values of fillet samples on the first day of the study, compared to the control group (P < 0.05). During storage, TVB-N levels showed slower increase in the treatment groups compared to the control group (P < 0.05). In addition, the marinating process led to significant changes in physicochemical parameters such as water holding capacity, color, texture, cooking loss, and drip loss compared to the control group (P < 0.05). In conclusion, the results of this study showed that the pulp of Rheum ribes L., which has a high antioxidant capacity and contains various bioactive compounds. Furthermore, S. Typhimurium, E. coli O157:H7 and L. monocytogenes were inhibited considerably by marinating Rheum ribes L. pulp with a combination of eugenol and thymol.

Evaluation of the Antibacterial, Anti-Inflammatory, And Bone-Promoting Capacity of UiO-66 Loaded with Thymol or Carvacrol

Oral infectious diseases have a significant impact on the health of oral and maxillofacial regions, as well as the overall well-being of individuals. Carvacrol and thymol, two isomers known for their effective antibacterial and anti-inflammatory properties, have gained considerable attention in the treatment of oral infectious diseases. However, their application as topical drugs for oral use is limited due to their poor physical and chemical stability. UiO-66, a metal-organic framework based on zirconium ion (Zr4+), exhibits high drug loading capability. Carvacrol and thymol were efficiently loaded onto UiO-66 with loading rates of 79.60 ± 0.71% and 79.65 ± 0.76%, respectively. The release rates of carvacrol and thymol were 77.82 ± 0.87% and 76.51 ± 0.58%, respectively, after a period of 72 h. Moreover, Car@UiO-66 and Thy@UiO-66 demonstrated excellent antibacterial properties against Candida albicans, Escherichia coli, and Staphylococcus aureus with minimum bactericidal concentrations (MBC) of 0.313 mg/mL, 0.313 mg/mL, and 1.25 mg/mL, respectively. Furthermore, based on the results of the CCK8 cytotoxicity assay, even at concentrations as high as 1.25 mg/mL, Car@UiO-66 and Thy@UiO-66 exhibited excellent biocompatibility with a relative cell survival rate above 50%. These findings suggest that Car@UiO-66 and Thy@UiO-66 possess favorable biocompatibility properties without significant toxicity towards periodontal membrane cells. Additionally, in vivo studies confirmed the efficacy of Car@UiO-66and Thy@UiO-66 in reducing inflammation, promoting bone formation through inhibition of TNF-a and IL6 expression, enhancement of IL10 expression, and acceleration of bone defect healing. Therefore, the unique combination of antibacterial, anti-inflammatory, and osteogenic properties make Car@UiO-66 and Thy@Ui O-66 promising candidates for the treatment of oral infectious diseases and repairing bone defects.

Using Essential Oils to Reduce Yersinia enterocolitica in Minced Meat and in Biofilms

Yersiniosis, one of the leading foodborne infections in the European Union, is caused by Yersinia enterocolitica. In this study, the antibacterial and antibiofilm effects of cinnamon (Cinnamomum zeylanicum Nees), clove (Syzygium aromaticum L.), oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), thyme (Thymus vulgaris L.), and winter savory (Satureja montana L.) essential oils were investigated against Y. enterocolitica strains belonging to the bioserotype 4/O:3. Cinnamon essential oil showed the highest antibacterial activity, with an MIC value 0.09 µL/mL, followed by oregano and thyme essential oils, with MIC values from 0.09 to 0.18 µL/mL, and from 0.18 to 0.23 µL/mL, respectively. Thyme essential oil at 0.23 µL/g (MIC) and at 0.46 µL/g (2MIC) significantly (p < 0.05) reduced the number of Y. enterocolitica by 0.38 log CFU/g and 0.64 log CFU/g, respectively, in minced pork meat during storage at 4 °C for 4 days. The Y. enterocolitica strains formed biofilms at 15 °C and 37 °C in tryptic soy broth and Luria-Bertani broth, while no biofilms were obtained at 5 °C, and in meat broth nutrient media. Applying the minimum bactericidal concentrations of cinnamon, clove, oregano, rosemary, thyme, and winter savory essential oils on preformed biofilms led to significant reductions being observed in the range from 45.34% to 78.89%. A scanning electron microscopy assay showed the devastating impact of oregano and thyme essential oils on the morphology of Y. enterocolitica bacterial cells. In conclusion, the results of this study show that essential oils possess high anti-Yersinia and antibiofilm effects.

Enhancing hamburger shelf life and quality using gallic acid encapsulated in gelatin/tragacanth gum complex coacervate

Considering mitigating oxidative degradation and inhibiting microbial proliferation in meat products, incorporating antioxidant and antimicrobial materials is critical to enhance shelf life, maintain quality, and ensure food safety. So, this study aimed to investigate the antimicrobial and antioxidant effects of encapsulated gallic acid on the quality of hamburgers during 30 days of storage. Gallic acid was microencapsulated in tragacanth gum/gelatin complex coacervate, and its encapsulation efficiency was optimized by the response surface method. The optimized encapsulation conditions were 1:4 polymer ratio (tragacanth to gelatin ratio); total polymer content, 0.9 %; pH, 3.5; and gallic acid content, 0.88 %, resulting in a 98 % encapsulation efficiency. The microcapsules were characterized using various techniques, including scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and differential scanning calorimetry. 400 ppm encapsulated gallic acid was added to the hamburger formulation, and various microbial properties, chemical analysis (peroxide value (POV) and thiobarbituric acid (TBA)), and sensory properties of the hamburgers were evaluated during storage. Results showed that gallic acid in the hamburgers decreased lipid oxidation from 0.126 to 0.103 mg MAD/kg in the TBA test and 12.73 to 11.03 meq/kg in the POV test during one month of storage. Also, phenolic compounds could prevent the growth and proliferation of spoilage microorganisms by damaging the microorganism cell walls and changing the metabolic processes. So, the amounts of total count and yeast and mold in the treated sample were lower than in the control sample. Significantly, adding encapsulated gallic acid did not negatively affect the flavor or overall evaluation of the samples. Overall, these findings suggested that encapsulated gallic acid is a suitable candidate to maintain chemical, microbial, and sensory characteristics of hamburgers over time.

Development of functional, sustainable pullulan-sodium alginate-based films by incorporating essential oil microemulsion for chilled pork preservation

Developing safe, eco-friendly, and functionally edible packaging materials has attracted global attention. Essential oils, can be incorporated into packaging materials as antioxidant and antibacterial agents. However, their high volatility and discontinuous film matrix issues may cause a rough film surface, limiting the application in food packaging. In this study, thyme essential oil microemulsion (TEO-M) was prepared and incorporated into a pullulan-sodium alginate (PS) film. The TEO-M incorporation endowed the PS film with antioxidant and UV protection properties. The antioxidant activities of the TEO-M-incorporated PS film were significantly better than those of the TEO-C (thyme essential oil coarse emulsion)-incorporated PS film. In comparison to TEO-C, the distribution of TEO-M in the film is more uniform. Lipid oxidation and the growth of microorganisms in chilled pork were inhibited by incorporating TEO-M at a concentration of 50 mg/mL in the PS film (PS-50M). After 10 days of storage at 4 °C, the total viable count (TVC) of chilled pork preserved in the PS-50M material was significantly reduced compared to the control group (P < 0.05). This study shows that incorporating TEO-M in the PS film provides a method for applying essential oils in food packaging, which may have great potential in the food industry.

Impact of sodium alginate-based film loaded with resveratrol and thymol on the shelf life of cooked sausage and the inoculated Listeria monocytogenes

In present study, sodium alginate biodegradable films containing different concentrations of resveratrol (RES: 0.002% and 0.004%) or thymol (THY: 0.5% and 1%) and their combinations were prepared, and evaluated for their effects on spoilage-related microbial profile, lipid oxidation, sensory properties, and protective effects against Listeria monocytogenes in beef mortadella sausage during 40 days storage at 4°C. The release rate of phenolic compounds was determined by the Folin-Ciocalteu test. To assess the shelf life of the product, changes in total viable count (TVC), lactic acid bacteria count (LAB), psychrotrophic bacteria count (PTC), pH levels, thiobarbituric acid reactive substances (TBARS) levels, and sensory characteristics (taste, color, odor, and overall acceptability) were evaluated. For the sensory evaluation, a panel of 70 semi-trained judges was selected according to their initial performance. Samples wrapped with sodium alginate films containing 1% THY (alone or combined with different concentrations of RES) exhibited lower bacterial counts compared to other experimental groups at the end of the storage period (6.01-6.35 vs. 6.71-8.17 log10 CFU/g for TVC, 5.37-5.83 vs. 6.07-7.11 log10 CFU/g for LAB, 5.08-5.18 vs. 5.40-7.23 log10 CFU/g for PTC, and 6.53-6.92 vs. 7.23-9.01 log10 CFU/g for inoculated L. monocytogenes). Sodium alginate films containing the combination of 0.004% RES and different concentrations of THY showed higher antioxidant effects than other experimental groups (TBARS values of 1.68-1.99 vs. 2.23-3.80 mg MDA/kg sample). The sodium alginate film containing 0.004% RES + 1% THY exhibited the highest antimicrobial and antioxidant activities and highest sensory scores among all treatments. These findings highlight the potential application of the sodium alginate film containing a combination of RES and THY as an active packaging material with natural preservatives in the meat products industry. This application can effectively extend the shelf life and enhance the microbial safety of clean-label cooked sausages during refrigerated storage.

Marinades Based on Natural Ingredients as a Way to Improve the Quality and Shelf Life of Meat: A Review

Marinating is a traditional method of improving the quality of meat, but it has been modified in response to consumer demand for "clean label" products. The aim of this review is to present scientific literature on the natural ingredients contained in marinades, the parameters of the marinating process, and certain mechanisms that bring about changes in meat. A review was carried out of publications from 2000 to 2023 available in Web of Science on the natural ingredients of meat marinades: fruit and vegetables, seasonings, fermented dairy products, wine, and beer. The review showed that natural marinades improve the sensory quality of meat and its culinary properties; they also extend its shelf life. They affect the safety of meat products by limiting the oxidation of fats and proteins. They also reduce biogenic amines and the formation of heterocyclic aromatic amines (HAAs) and polycyclic aromatic hydrocarbons (PAHs). This is possible due to the presence of biologically active substances and competitive microflora from dairy products. However, some marinades, especially those that are acidic, cause a slightly acidic flavour and an unfavourable colour change. Natural compounds in the ingredients of marinades are accepted by consumers. There are no results in the literature on the impact of natural marinades on the nutritional value and health-promoting potential of meat products, so it can be assumed that this is a future direction for scientific research.

Green label marinades: A solution to salmonella and campylobacter in chicken products?

Introduction

The presence of meat-borne pathogens entering the home remains a concern for consumers, despite advances made in improving antimicrobial interventions and systems within the processing line. Naturally antibacterial food ingredients including citrus juice and essential oils have been proven to inhibit the proliferation of microbial growth with varying success.

Aims

This study aims to investigate the antimicrobial and sensory effects of mixtures of essential oils, fruit juices and herbs at established Minimum Inhibitory Concentrations (MICs) for their biopreservative effect on general microbiota of chicken and against chicken challenged with selected pathogenic/surrogate microorganisms.

Materials and methods

Three marinade compositions were designed for use on chicken meat; lemon juice, thyme oil and black pepper (M1), lime juice, lemongrass oil and chilli paste (M2), and olive oil, oregano oil, basil oil and garlic paste (M3). These marinades were assessed for antibacterial effects against Salmonella enterica, Campylobacter jejuni and Listeria innocua on marinaded chicken drumsticks stored in aerobic conditions at 4 °C. Consumer tasting sessions were also conducted with a small focus group using selected final marinades.

Results

M1 and M2 were effective at significantly reducing initial pathogen carriage from 6 Log CFU/g to 2 Log CFU/g on refrigerated chicken meat as well as increasing the shelf-life of the product during cold-storage from 2 days to 7 days. However, consumer studies indicate that the flavours these marinades impart to treated products can be strong.

Conclusion

These findings indicate that these designed marinades have shown excellent potential to improve food safety as well as shelf-life for the consumer, particularly in settings where food safety is often compromised such as barbecuing or in care settings. However, further recipe optimisation is required to make these marinades acceptable to consumers.

Antimicrobial and Antibiofilm Potential of Thymus vulgaris and Cymbopogon flexuosus Essential Oils against Pure and Mixed Cultures of Foodborne Bacteria

The spread of pathogenic and food spoilage microorganisms through the food chain still faces major mitigation challenges, despite modern advances. Although multiple cleaning and disinfection procedures are available for microbial load reduction in food-related settings, microbes can still remain on surfaces, equipment, or machinery, especially if they have the ability to form biofilms. The present study assessed the biofilm-forming properties of pure and mixed cultures of foodborne and spoilage bacteria (Listeria monocytogenes, Enterococcus faecalis, Aeromonas hydrophila, Brochothrix thermosphacta), using polystyrene and stainless steel contact surfaces. Subsequently, the antimicrobial and antibiofilm properties of Thymus vulgaris and Cymbopogon flexuosus essential oils—EOs—were evaluated against these bacteria. Moreover, in silico prediction of the absorption and toxicity values of the EOs’ major constituents was also performed, perceiving the putative application in food-related settings. Overall, biofilm formation was observed for all microbes under study, at different temperatures and both contact surfaces. In polystyrene, at 25 °C, when comparing pure with mixed cultures, the combination Listeria–Aeromonas achieved the highest biofilm biomass. Moreover, at 4 °C, increased biofilm formation was detected in stainless steel. Regarding thyme, this EO showed promising antimicrobial features (especially against A. hydrophila, with a MIC of 0.60 µg/µL) and antibiofilm abilities (MBEC of 110.79 µg/µL against L. monocytogenes, a major concern in food settings). As for lemongrass EO, the highest antimicrobial activity, with a MIC of 0.49 µg/µL, was also observed against L. monocytogenes. Overall, despite promising results, the in situ effectiveness of these essential oils, alone or in combination with other antimicrobial compounds, should be further explored.

Biocontrol Activity of Aromatic and Medicinal Plants and Their Bioactive Components against Soil-Borne Pathogens

Soil-borne phytopathogens can have detrimental effects on both cereal and horticultural crops resulting in serious losses worldwide. Due to their high efficiency and easy applicability, synthetic pesticides are still the primary choice in modern plant disease control systems, but stringent regulations and increasing environmental concerns make the search for sustainable alternatives more pressing than ever. In addition to the incorporation of botanicals into agricultural practices, the diversification of cropping systems with aromatic and medicinal plants is also an effective tool to control plant diseases through providing nutrients and shaping soil microbial communities. However, these techniques are not universally accepted and may negatively affect soil fertility if their application is not thoroughly controlled. Because the biocontrol potential of aromatic and medicinal plants has been extensively examined over the past decades, the present study aims to overview the recent literature concerning the biopesticide effect of secondary metabolites derived from aromatic and medicinal plants on important soil-borne plant pathogens including bacteria, fungi, and nematodes. Most of the investigated herbs belong to the family of Lamiaceae (e.g., Origanum spp., Salvia spp., Thymus spp., Mentha spp., etc.) and have been associated with potent antimicrobial activity, primarily due to their chemical constituents. The most frequently tested organisms include fungi, such as Rhizoctonia spp., Fusarium spp., and Phytophthora spp., which may be highly persistent in soil. Despite the intense research efforts dedicated to the development of plant-based pesticides, only a few species of aromatic herbs are utilized for the production of commercial formulations due to inconsistent efficiency, lack of field verification, costs, and prolonged authorization requirements. However, recycling the wastes from aromatic and medicinal plant-utilizing industries may offer an economically feasible way to improve soil health and reduce environmental burdens at the same time. Overall, this review provides comprehensive knowledge on the efficiency of aromatic herb-based plant protection techniques, and it also highlights the importance of exploiting the residues generated by aromatic plant-utilizing sectors as part of agro-industrial processes.

Comparing the Effects of Thyme (Zataria multiflora) and Rosemary (Rosmarinus officinalis) Essential Oils on Microbiological, Physicochemical, and Sensory Properties of Vacuum-Packaged and Refrigerated Chicken Breast

This study aimed to compare the effects of thyme and rosemary essential oils (EOs) with vacuum packaging on shelf life extension and organoleptic properties of chicken breast meat. For this purpose, two concentrations of 0.1% and 0.3% (v/w) from thyme and rosemary EOs were added individually to fresh chicken breast samples, packed under vacuum conditions, and stored at 4°C for 12 days. All the samples were evaluated for microbiological, physicochemical, and sensory properties at 3-day intervals. The results showed that the thyme EO treatments, especially at 0.3% concentration, significantly reduced both total and psychrotrophic colony counts, and they were more effective in reducing microbial counts compared to rosemary EO treatments. Moreover, thyme EO significantly controlled Escherichia coli growth in treated samples. TBA values in treated samples with thyme EOs were significantly less than in rosemary EOs and control samples. Results indicated that rosemary EO treatments had the lowest pH during 12 days. Colorimetric and organoleptic analysis of the samples showed statistical differences on various days. In the EOs-treated chicken breasts, the color and texture of the samples improved compared to controls, but the taste and odor were not desired at the higher concentration of thyme and rosemary EOs.