A current opinion on the antimicrobial importance of popular pepper essential oil and its application in food industry

Fabrication, characterization and antimicrobial activity of chitosan/tragacanth gum/polyvinyl alcohol composite films incorporated with cinnamon essential oil nanoemulsion

The aim of this investigation was to prepare and characterize active composite films made of chitosan (CS), tragacanth gum (TG), polyvinyl alcohol (PVA) and loaded with different concentrations of cinnamon essential oil (CEO) nanoemulsion (CEO, 2 and 4 % v/v). For this purpose, the amount of CS was fixed and the ratio of TG to PVA (90:10, 80:20, 70:30, and 60:40) was considered variable. The physical (thickness and opacity), mechanical, antibacterial and water-resistance properties of the composite films were evaluated. According to the microbial tests, the optimal sample was determined and evaluated with several analytical instruments. CEO loading increased the thickness and EAB of composite films, while decreasing light transmission, tensile strength, and water vapor permeability. All the films containing CEO nanoemulsion had antimicrobial properties, but this activity was higher against Gram-positive bacteria (Bacillus cereus and Staphylococcus aureus) than Gram-negative types (Escherichia coli (O157:H7) and Salmonella typhimurium). According to the results of attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA) and X-ray diffraction (XRD), the interaction between the components of the composite film was confirmed. It can be concluded that the CEO nanoemulsion can be incorporated in CS/TG/PVA composite films and successfully used as active and environmentally friendly packaging.

Enzyme-assisted polysaccharides extraction from Calocybe indica: Synergistic antibiofilm and oxidative stability of essential oil nanoemulsion

Recently, mushroom polysaccharides have been explored to attribute to vital biologically important functions, and several extraction techniques can be employed, therefore, polysaccharides were extracted from the edible mushroom Calocybe indica to explore its functionality. Multiple enzymes viz., cellulase, pectinase, and protease (1:1:1) at temperature 47 °C and pH 4.64 with an extraction time of 2 h yielded 7.24 % polysaccharide content. The thermograph curve of polysaccharides showed two-stage decomposition at a different temperature range and decomposition of polysaccharides initiated with an onset temperature of 226.77 °C and a maximum peak at 248.90 °C. Hydrodistillation processed Eucalyptus globulus leaf oil was characterized using the chromatography technique and eucalyptol, p-cymene, Γ-terpinene, 4-epi-cubebol, spathulenol, viridiflorol, and p-mentha-1,5-dien-8-ol was observed as major components. As well, we formulated nanoemulsion using mushroom polysaccharide and eucalyptus leaf oil with 140.8 nm and evaluated synergistic antimicrobial and antibiofilm activity. MIC and MBC values for Pseudomonas aeruginosa, E. coli, and S. typhi were 12.50-3.125 and 6.25-1.56, and for S. aureus were 6.25, 6.25, 3.125, and 3.125, 3.125, 1.56 and for C. albicans the values were 12.50,12.50, 6.250 and 6.25,6.25, and 3.125 μl/mL respectively. The polysaccharides, essential oil, and nanoemulsion showed remarkable antibiofilm activity against S.aureus with inhibition of 57.42 ± 0.19, 59.62 ± 0.15, and 69.34 ± 0.19 %, while E. coli showed the least antibiofilm activity. However, all three tested samples showed significant (p < 0.05) differences against tested pathogenic microorganisms with inhibition of biofilm formation. Therefore, it could be inferred that the synergistic properties of essential oils with mushroom polysaccharides are a promising strategy to enhance antimicrobial efficacy and control foodborne pathogens.

Development of food-grade antimicrobials of fenugreek oil nanoemulsion-bioactivity and toxicity analysis

Antimicrobials of natural origin are proving to be an effective solution to emerging antimicrobial resistance and its physiological side effects. Recent studies have demonstrated that essential oils encapsulated in the form of nanoemulsions have better antimicrobial activity than the oil itself, possibly due to its high stability, solubility, sustained release, and increased bioavailability. In the present study, fenugreek oil-a well-known antimicrobial and antioxidant-has been used to fabricate nanoemulsion (NE), with an objective to meet potential alternative to synthesized antimicrobials. A combination of three different components, water, fenugreek oil, and Tween 80, has been used to prepare the nanoemulsions of different size and one of the most stable nanoemulsion with lowest concentration of surfactant Tween 80 was used to assess its bioactivity, antimicrobial properties, and toxicity against human hepatic cell line. Among all the formulations, nano-emulsion with 2.5% oil concentration, 30 min sonication (hydrodynamic size 135.2 nm, zeta potential 36.8 mV, PDI 0.135, and pH 5.12), was selected for all studies. The nanoemulsion showed potential antibacterial activity against all the microbial strains (Escherichia coli, Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) used in this study. Interestingly, the nanoemulsion showed potential antibacterial activity against P. aeruginosa, known to show resistance against ampicillin. The toxicity evaluation in human hepatic cell line (WRL-68) indicated no significant toxicity of nanoemulsion up to the concentration of 800 µg/ml. The synthesized nanoemulsion thus has a translational potential as a food-grade non-toxic natural nanoantimicrobials.

An Active Bio-Based Food Packaging Material of ZnO@Plant Polyphenols/Cellulose/Polyvinyl Alcohol: DESIGN, Characterization and Application

Active packaging materials protect food from deterioration and extend its shelf life. In the quest to design intriguing packaging materials, biocomposite ZnO/plant polyphenols/cellulose/polyvinyl alcohol (ZnPCP) was prepared via simple hydrothermal and casting methods. The structure and morphology of the composite were fully analyzed using XRD, FTIR, SEM and XPS. The ZnO particles, plant polyphenols (PPL) and cellulose were found to be dispersed in PVA. All of these components share their unique functions with the composite's properties. This study shows that PPL in the composite not only improves the ZnO dispersivity in PVA as a crosslinker, but also enhances the water barrier of PVA. The ZnO, PPL and cellulose work together, enabling the biocomposite to perform as a good food packaging material with only a 1% dosage of the three components in PVA. The light shielding investigation showed that ZnPCP-10 can block almost 100% of both UV and visible light. The antibacterial activities were evaluated by Gram-negative Escherichia coli (E. coli) and Gram-positive staphylococcus aureus (S. aureus), with 4.4 and 6.3 mm inhibition zones, respectively, being achieved by ZnPCP-10. The enhanced performance and easy degradation enables the biocomposite ZnPCP to be a prospect material in the packaging industry.

Arbutus unedo leaf extracts as potential dairy preservatives: case study on quark cheese

The plant kingdom is an endless source of molecules that can be applied in almost all realms of society. The food industry has profited from the use of plants and their derived materials for many decades. Recently, the food industry has been looking into plants to find different ways of either preserving, coloring or sweetening foods. In this work, leaf extracts of Arbutus unedo L. obtained by dynamic maceration and ultrasound assisted extraction with prior optimization of their extraction conditions through the response-surface methodology, were incorporated in quark cheese as natural preservatives and analyzed over 8 days of shelf-life. Both extracts showed antioxidant activity with no toxicity towards primary cell lines at the maximum tested concentration, as well as antibacterial activity, especially against Gram-positive strains. After their incorporation in quark cheese, no significant changes were observed in the nutritional profile and physical traits of the quark cheeses, while the microbial load was highly reduced in the cheese, especially using the extracts obtained from dynamic maceration. Thus, leaf extracts of A. unedo can be promising candidates for use in the food industry as natural preservatives.

Effect of pepper (Zanthoxylum bungeanum Maxim.) essential oil on quality changes in rabbit meat patty during chilled storage

In this paper, the components of Zanthoxylum bungeanum Maxim. essential oil (ZBMEO) were analyzed. The efficacy of different concentrations of ZBMEO on the change in physical and chemical indicators of the rabbit meat patty was evaluated. Furthermore, kinetics models were employed to calculate the lipid oxidation induction period and microbial growth lag time. GC-MS analysis revealed that the major chemical components in ZBMEO included linalool, limonene, and sabinene. Results of the storage experiment indicated that ZBMEO had a good inhibition effect on lipid and protein oxidation, microbial growth, and formation of TVB-N, as well as slowed down the rate of change in color and pH during the 12 days storage time of rabbit meat. The models showed that adding ZBMEO could delay the lipid oxidation induction period, and extend the microbial growth lag time. Overall data showed that ZBMEO is a promising natural additive to maintain the quality of rabbit meat patty.

Morphological and metabolomics impact of sublethal doses of natural compounds and its nanoemulsions in Bacillus cereus

Microbiological safety in food industry are always a concern regarding sublethal tolerance in bacteria for common and natural sanitizers. Natural bacteriocins, such as nisin (NIS), may negatively interfere in the efficiency of major compounds of essential oils against foodborne pathogenic bacteria. However, nanoemulsioned forms increase the bactericidal potential of natural compounds acting synergistically. In this study, cinnamaldehyde (CIN), citral (CIT), and linalool (LIN) were evaluated independently, associated with NIS, and in nanoemulsions (NEs) against Bacillus cereus using untargeted-metabolomics. Results revealed morphological changes in the structure of B. cereus treated with NEs of CIN and CIT, both NIS-associated. In addition, sensibility tests and UHPLC-QTOF-MS analyses indicated that NIS might react together with CIT reducing the bactericidal efficiency, while the nanoemulsion of CIT effect was enhanced by NIS in nanoemulsioned forms. This study highlights the importance of prudent administration of natural compounds as antimicrobial agents to prevent sublethal tolerance in pathogenic bacteria.

Natural Anti-Microbials for Enhanced Microbial Safety and Shelf-Life of Processed Packaged Meat

Microbial food contamination is a major concern for consumers and food industries. Consumers desire nutritious, safe and “clean label” products, free of synthetic preservatives and food industries and food scientists try to meet their demands by finding natural effective alternatives for food preservation. One of the alternatives to synthetic preservatives is the use of natural anti-microbial agents in the food products and/or in the packaging materials. Meat and processed meat products are characteristic examples of products that are highly perishable; hence natural anti-microbials can be used for extending their shelf-life and enhancing their safety. Despite several examples of the successful application of natural anti-microbial agents in meat products reported in research studies, their commercial use remains limited. This review objective is to present an extensive overview of recent research in the field of natural anti-microbials, covering essential oils, plant extracts, flavonoids, animal-derived compounds, organic acids, bacteriocins and nanoparticles. The anti-microbial mode of action of the agents, in situ studies involving meat products, regulations and, limitations for usage and future perspectives are described. The review concludes that naturally derived anti-microbials can potentially support the meat industry to provide “clean label”, nutritious and safe meat products for consumers.

Capsaicin: Plants of the Genus Capsicum and Positive Effect of Oriental Spice on Skin Health

BACKGROUND

Capsaicin, the main pungent ingredient in hot chili peppers, causes excitation of small sensory neurons. It also provides the basic pungent flavor in Capsicum fruits.

SUMMARY

Capsaicin plays a vital role as an agonist for the TRPV1 (transient receptor potential cation channel, subfamily V, member 1) receptor. TRPV1 is essential for the reduction of oxidative stress, pain sensations, and inflammation. Therefore, it has many pros related to health issue. Activation and positive impact of TRPV1 via capsaicin has been studied in various dermatological conditions and in other skin-related issues. Past studies documented that capsaicin plays a vital role in the prevention of atopic dermatitis as well as psoriasis. Moreover, TRPV1 is also very important for skin health because it acts as a capsaicin receptor. It is found in nociceptive nerve fibers and nonneural structures. It prompts the release of a compound that is involved in communicating pain between the spinal cord nerves and other parts of the body. Key Messages: Here, we summarize the growing evidence for the beneficial role of capsaicin and TRPV1 and how they help in the relief of skin diseases such as inflammation, permeation, dysfunction, atopic dermatitis, and psoriasis and in pain amplification syndrome.

Comparative Evaluation of Piper nigrum, Rosmarinus officinalis, Cymbopogon citratus and Juniperus communis L. Essential Oils of Different Origin as Functional Antimicrobials in Foods

Essential oils can be used as preservatives in foods because of their ability to inhibit bacteria growth in low concentration, which does not influence on foods' organoleptic properties and does not generate the resistance mechanisms in cells. The aim of that work was to compare the effectiveness of commercial oils from black pepper (Piper nigrum), rosemary (Rosmarinus officinalis), lemongrass (Cymbopogon citratus) and juniper (Juniperus communis L.) with oils obtained in our laboratory. The typical cultivation method was supported by the flow cytometry to detect the cells of very low physiologic and metabolic activity. Our investigation demonstrated that both types of oils can effectively inhibit the growth of saprophytic bacteria P. orientalis. The oils distilled in our laboratory had a bacteriostatic effect at a lower concentration, which is important for application in the food industry. Flow cytometry analyzes and confirmed the thesis that essential oils do not have a germicidal effect on bacteria cells.

The Influence of Selected Plant Essential Oils on Morphological and Physiological Characteristics in Pseudomonas Orientalis

The aim of this work was to estimate the antibacterial activity of selected essential oils on Pseudomonas orientalis strains isolated from foods. An attempt was also made to identify the mechanisms of the action of the plant oils. Classical methods of assessment of the effectiveness of antimicrobial activity of oils were linked with flow cytometry. It was observed that bergamot, lemongrass, bitter orange, juniper, and black pepper oils have bacteriostatic effect against P. orientalis P49. P. orientalis P110 is sensitive to lime, lemongrass, juniper, rosemary, and black pepper oils. Additionally, plant oils with biostatic effect on P. orientalis limited the intracellular metabolic activity of cells; this was closely linked with the ability of plant oils' bioactive components to interact with bacteria cell membrane, causing the release of membrane proteins. As a result, the selective permeability of the cell membranes were damaged and the bacterial shape was transformed to coccoid in form.

Influence of sub-inhibitory concentration of selected plant essential oils on the physical and biochemical properties of Pseudomonas orientalis

Plant essential oils have bacteriostatic activity in very low concentrations, thus they can be used as natural preservative in food products. The aim of this work was to understand the inhibitory and non-bactericidal effects of essential oils in low concentrations. To meet this aim some physical and biochemical properties of two P. orientalis strains isolated from food probes were investigated under the influence of plant oils. Control probes - without oils - played an important role in our investigations because P. orientalis is not a well-known and described species. Thus, these results allow us to gain additional knowledge about bacteria from P. orientalis species. The obtained results are proof that under the influence of oils, bacteria lose their ability to move, change their morphology, and also reduce their metabolic activity. However, they do not die, and properties such as the ability to produce ammonia, the ability to production of indole from the amino acid tryptophan as well as the ability to assimilation of saccharides are maintained.

Antimicrobial and antioxidant activities of hydrocarbon and oxygenated monoterpenes against some foodborne pathogens through in vitro and in silico studies

The present work describes the antimicrobial action of 25 monoterpenes (six hydrocarbons, five ketones, two aldehydes, six alcohols and six acetate analogues) against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus and antifungal activity against Aspergillus flavus. The antibacterial activity was evaluated by broth microdilution technique as a minimum inhibitory concentration (MIC) and the antifungal activity was performed by mycelia radial growth technique as the effective concentration causing 50% inhibition of the mycelial growth (EC₅₀). The results showed that thymol and α-terpineol were the most potent against E. coli (MIC = 45 and 55 mg/L, respectively) and S. aureus (MIC = 135 and 225 mg/L, respectively). The results also showed that thymol displayed the maximum antifungal action against A. flavus with EC₅₀ 20 mg/L. Furthermore, the antioxidant activity was determined using N,N-dimethyl-1,4-phenylenediamine (DMPD) and the results showed that geraniol were the most potent compound (IC₅₀ = 19 mg/L). Molecular docking studies indicated that the compounds displayed different binding interactions with the amino acid residues at the catalytic sites of N5-carboxyaminoimidazole synthetase and oxysterol binding protein Osh4 enzymes. Non-covalent interactions including van der Waals, hydrogen bonding as well as hydrophobic were observed between the compounds and the enzymes. A significant relationship was found between the docking score and the biological activity of the tested monoterpenes compared to the ceftriaxone and carbendazim as standard bactericide and fungicide, respectively. In silico ADMET properties were also performed and displayed potential for the development of promising antimicrobial agents. For these reasons, these compounds may be considered as potential ecofriendly alternatives in food preservation to delay or prevent the microbial infection and prolong the shelf life of food products.