Essential oils as antimicrobials in food systems – A review

Synergistic inhibition of Salmonella Typhimurium and Staphylococcus aureus in apple jam by cinnamaldehyde and potassium sorbate

The objective of this study was to evaluate the antimicrobial effectiveness of cinnamaldehyde (CIN) and potassium sorbate (P.S.), alone and in combination, against Salmonella Typhimurium and Staphylococcus aureus in vitro and in apple jam. Antimicrobial activity in vitro was investigated by minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC), time-kill assay and determination of fractional inhibitory concentration index. CIN MIC and MBC was 312 μg/mL. P.S. MIC and MBC were 2500 and 5000 μg/mL, respectively, against S. Typhimurium; and 10,000 and 20,000 μg/mL, respectively, against S. aureus. The compounds combined exhibited a synergistic effect (FIC < 0.5), inhibiting S. Typhimurium growth after 12 h and S. aureus after 24 h. The effect of CIN and P.S., at sub-inhibitory concentrations, against bacterial strains in apple jam was evaluated during storage. Physicochemical and sensory analyses were also performed. No cultivable S. Typhimurium or S. aureus cells were recovered in apple jam supplemented with CIN + P.S. on the third day of storage. The addition of CIN and P.S. did not affect the physicochemical properties and sensory evaluation showed a score above 7.0. CIN and P.S. association at sub-inhibitory concentrations was effective in controlling foodborne pathogens and improved the shelf life of apple jam.

Potential fungicidal and antiaflatoxigenic effects of cinnamon essential oils on Aspergillus flavus inhabiting the stored wheat grains

Wheat is one of the essential crops for the human and animal nutrition, however, contamination with aflatoxigenic fungi, due to the improper storage conditions and high humidity, was the main global threats. So, preventing the growth of aflatoxigenic fungi in stored wheat grains, by using different essential oils was the main objective of this work. Aspergillus flavus EFBL-MU12 PP087400, EFBL-MU23 PP087401 and EFBL-MU36 PP087403 isolates were the most potent aflatoxins producers inhabiting wheat grains. The effect of storage conditions of wheat grains "humidity, temperature, incubation period, and pH" on growth of A. flavus, was assessed by the response surface methodology using Plackett-Burman design and FCCD. The highest yield of aflatoxins EFBL-MU12 B1 and B2 by A. flavus grown on wheat grains were 145.3 and 7.6 μg/kg, respectively, at incubation temperature 35°C, 16% moisture contents, initial pH 5.0, and incubated for 14 days. The tested oils had a powerful antifungal activity for the growth and aflatoxins production by A. flavus in a concentration-dependent manner. Among these oils, cinnamon oil had the highest fungicidal activity for A. flavus at 0.125%, with about 85-90 % reduction to the aflatoxins B1 and B2, conidial pigmentation and chitin contents on wheat grains. From the SEM analysis, cinnamon oils had the most deleterious effect on A. flavus with morphological aberrations to the conidial heads, vegetative mycelia, alteration in conidiophores identity, hyphae shrank, and winding. To emphasize the effect of the essential oils on the aflatoxins producing potency of A. flavus, the molecular expression of the aflatoxins biosynthetic genes was estimated by RT-qPCR. The molecular expression of nor-1, afLR, pKsA and afLJ genes was suppressed by 94-96%, due to cinnamon oil at 0.062% compared to the control. Conclusively, from the results, cinnamon oils followed by the peppermint oils displayed the most fungicidal activity for the growth and aflatoxins production by A. flavus grown on wheat grains.

Citric acid crosslinked carboxymethyl cellulose edible films: A case study on preserving freshness in bananas

The study involves the preparation and characterization of crosslinked-carboxymethyl cellulose (CMC) films using varying amounts of citric acid (CA) within the range 5 %-20 %, w/w, relative to the dry weight of CMC. Through techniques such as Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, carbonyl content analysis, and gel fraction measurements, the successful crosslinking between CMC and CA is confirmed. The investigation includes an analysis of chemical structure, physical and optical characteristics, swelling behavior, water vapor transmission rate, moisture content, and surface morphologies. The water resistance of the cross-linked CMC films exhibited a significant improvement when compared to the non-crosslinked CMC film. The findings indicated that films crosslinked with 10 % CA demonstrated favorable properties for application as edible coatings. These transparent films, ideal for packaging, prove effective in preserving the quality and sensory attributes of fresh bananas, including color retention, minimized weight loss, slowed ripening through inhibiting amyloplast degradation, and enhanced firmness during storage.

Eco-Friendly Sanitization of Indoor Environments: Effectiveness of Thyme Essential Oil in Controlling Bioaerosol Levels and Disinfecting Surfaces

Bioaerosols and pathogens in indoor workplaces and residential environments are the primary culprits of several infections. Techniques for sanitizing air and surfaces typically involve the use of UV rays or chemical sanitizers, which may release chemical residues harmful to human health. Essential oils, natural substances derived from plants, which exhibit broad antimicrobial properties, could be a viable alternative for air and surface sanitation. The objective of this study has been to investigate the efficacy of thyme essential oil (TEO) in environmental sanitation processes. In Vitro assays through agar well diffusion, disk volatilization and tube dilution methods revealed significant antimicrobial activity of TEO 100% against foodborne and environmental isolates, with both bacteriostatic/fungistatic and bactericidal/fungicidal effects. Therefore, aqueous solutions of TEO 2.5% and 5% were formulated for air sanitation through nebulization and surface disinfection via direct contact. Bioaerosol samples and surface swabs were analyzed before and after sanitation, demonstrating the efficacy of aqueous solutions of TEO in reducing mesophilic and psychrophilic bacteria and environmental fungi levels in both air and on surfaces. The obtained results prove the antimicrobial potential of aqueous solutions of TEO in improving indoor air quality and surface cleanliness, suggesting thyme essential oil as an effective and safe natural sanitizer with minimal environmental impact compared to dangerous chemical disinfectants.

Evolution and chemical diversity of the volatile compounds in Salvia species

INTRODUCTION

The plant essential oils are composed of volatile compounds and have significant value in preventing and treating neurological diseases, anxiety, depression, among others. The genus Salvia has been shown to be an important medicinal resource, especially the aerial parts of genus Salvia, which are rich in volatile compounds; however, the chemical diversity and distribution patterns of volatile compounds in Salvia species are still unknown.

OBJECTIVE

The work is performed to analyse the chemical diversity and distribution patterns of volatile compounds in genus Salvia.

METHODS

The genomic single nucleotide polymorphisms (SNPs) combined with gas chromatography-mass spectrometry (GC-MS) were used to explore the evolution and chemical diversity of Salvia volatile compounds. Initially, the genetic relationship of genus Salvia was revealed by phylogenetic tree that was constructed based on SNPs. And then, GC-MS was applied to explore the chemical diversity of volatile compounds.

RESULTS

The results indicated that the volatile compounds were mainly monoterpenoids, sesquiterpenoids, and aliphatic compounds. The genomic SNPs divided species involved in this work into four branches. The volatile compounds in the first and second branches were mainly sesquiterpenoids and monoterpenoids, respectively. Species in the third branch contained more aliphatic compounds and sesquiterpenoids. And those in the fourth branch were also rich in monoterpenoids but had relatively simple chemical compositions.

CONCLUSION

This study offered new insights into the phylogenetic relationships besides chemistry diversity and distribution pattern of volatile compounds of genus Salvia, providing theoretical guidance for the investigations and development of secondary metabolites.

Comparative analysis of chemical profiles, antioxidant, antibacterial, and anticancer effects of essential oils of two Thymus species from Montenegro

The essential oils of Thymus vulgaris (TVEO) and Thymus serpyllum (TSEO) show different biological activities. The aim of the study was to evaluate the biological activities of TVEO and TSEO from Montenegro. The main components of TVEO were p-cymene (29.52%), thymol (22.8%) and linalool (4.73%) while the main components of TSEO were p-cymene (19.04%), geraniol (11,09%), linalool (9.16%), geranyl acetate (6.49%) and borneol (5.24%). Antioxidant activity determined via DPPH for TVEO was 4.49 and FRAP 1130.27, while for TSEO it was estimated that DPPH was 4.88 μL/mL and FRAP was 701.25 μmol FRAP/L. Both essential oils were active against all tested bacteria, with the highest level of sensitivity of E. coli with MIC of 1.5625 μL/mL. Essential oils showed strong cytotoxic effects on human cancer cell lines, with IC50 values ranging from 0.20 to 0.24 μL/mL for TVEO and from 0.32 to 0.49 μL/mL for TSEO. TVEO caused apoptosis in cervical adenocarcinoma HeLa cells through activation of caspase-3 and caspase-8, while TSEO caused apoptosis through caspase-3. EOs decreased levels of oxidative stress in normal MRC-5 cells. HeLa cells treated with TVEO had reduced MMP2 expression levels, while cells treated with TSEO had lowered MMP2 and MMP9 levels. The treatment of HeLa cells with TVEO increased the levels of miR-16 and miR-34a, indicating potential tumor-suppressive properties. Our findings suggest that Thymus essential oils may be considered as good candidates for further investigation as cancer-chemopreventive and cancer-therapeutic agents.

Characterization of Salmonella phages isolated from poultry coops and its effect with nisin on food bio-control

Salmonella is a bacterium associated with food contaminated by various animals, primarily poultry. Interest and research on bacteriophages are increasing because they can be used as an alternative against increasing antibiotic resistance. In our study, eight Salmonella-specific lytic bacteriophages were isolated from chicken feces. Two of the isolated phages (AUFM_Sc1 and AUFM_Sc3) were chosen for their characterization due to their broader host range. Based on morphological and genomic analysis, AUFM_Sc1 was identified to be close to similar Enterobacteria spp. CC31 (Myoviridae) and AUFM_Sc3 was identified to be close to Salmonella phage vB_Sen_I1 (Demerecviridae (formerly Siphoviridae)). Although these phages have shown promise for use in phage therapy applications for chickens, further studies are needed on their suitability. When a cocktail of these phages (AUFM_Sc1 + AUFM_Sc3) and nisin combination was applied on chicken breast meat, it was determined that it was effective against Salmonella contamination and while a good inhibitory effect was observed on the food, especially during the first 48 h, the effect decreased later, but the bacterial concentration was still low compared to the control group. Therefore, it is considered that the combination of AUFM_Sc1 + AUFM_Sc3 + nisin can be used as a food preservative against Salmonella.

Chemical profile and biological properties of the Piper corcovadense C.DC. essential oil

The essential oil from Piper corcovadense D.DC. (EOPc), an important plant belonging to the Piperaceae family, which is commonly found in the northern region of Brazil and poorly explored scientifically, was used in this study. Thus, the EOPc was characterized chemically by Gas Chromatography/Mass Spectrometry (GC/MS) and the antioxidant and antimicrobial activities and their potential effects on cutaneous melanoma (SK-MEL-28) and healthy peripheral blood mononuclear (PBMC) cells were determined. The major compounds identified in the EOPc were: trans-sesquisabinene hydrate, trans-caryophyllene, β-pinene, trans-β-farnesene, 14-hydroxycaryophyllene, limonene and p-cymene. The EOPc demonstrated antioxidant activity as evaluated by Folin-Ciocalteu reagent (FC) reducing capacity, DPPH, and ABTS methods. The values found were respectively 5.41 ± 0.17 mg GAE mL-1 (GAE: Gallic acid equivalent), 2.88 ± 0.17 µmol TE mL-1 (TE: Trolox equivalent) and 6.26 ± 0.02 µmol TE mL-1. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for different bacterial strains. The EOPc at a concentration of 2.61 µg mL-1 exhibited both bactericidal and bacteriostatic properties against Escherichia coli. The EOPc showed potential antitumor activity as it reduced the cell viability of human cutaneous melanoma cells SK-MEL-28. Besides, the EOPc did not exhibit cytotoxic activity against healthy PBMCs, indicating that it does not harm healthy cells at the tested concentrations. The EOPc increased the levels of ROS at concentrations of 250 µg mL-1. The EOPc also did not stimulate the mobilization of endogenous antioxidant defenses, as assessed by total thiol (PSH) and non-protein thiols (NPSH). Thus, the study suggests that the EOPc has antioxidant and antimicrobial properties due to the presence of specific compounds. It also exhibits antitumor potential against cutaneous melanoma cells while showing no cytotoxicity to healthy PBMCs. It directly influenced ROS levels at the highest tested concentration in the cells, suggesting an antitumor effect related to the intrinsic apoptosis pathway. Nevertheless, while the study has initial findings, the results are promising and indicate an attractive biological potential of P. corcovadense, mainly in human cutaneous melanoma cells.

Salmonella in eggs and egg-laying chickens: pathways to effective control

Eggs contaminated with Salmonella have been internationally significant sources of human illness for several decades. Most egg-associated illness has been attributed to Salmonella serovar Enteritidis, but a few other serovars (notably S. Heidelberg and S. Typhimurium) are also sometimes implicated. The edible interior contents of eggs typically become contaminated with S. Enteritidis because the pathogen's unique virulence attributes enable it to colonize reproductive tissues in systemically infected laying hens. Other serovars are more commonly associated with surface contamination of eggshells. Both research and field experience have demonstrated that the most effective overall Salmonella control strategy in commercial laying flocks is the application of multiple interventions throughout the egg production cycle. At the preharvest (egg production) level, intervention options of demonstrated efficacy include vaccination and gastrointestinal colonization control via treatments such as prebiotics, probiotics, and bacteriophages, Effective environmental management of housing systems used for commercial laying flocks is also essential for minimizing opportunities for the introduction, transmission, and persistence of Salmonella in laying flocks. At the postharvest (egg processing and handling) level, careful regulation of egg storage temperatures is critical for limiting Salmonella multiplication inside the interior contents.

Growth kinetics of Lactococcus lactis and Lactobacillus casei in liquid culture medium containing as prebiotics inulin or fructose

BACKGROUND

Predictive microbiology is a tool that allows us to evaluate the behavior of the concentration of biomass and estimated cells under extrinsic conditions, providing scientific and industrial benefits. In the present study, the growth of L. lactis and L. casei combined with inulin and fructose was modeled using the Gompertz sigmoidal growth functions and plotted using data obtained from batch culture in relation to biomass and cell concentration expressed as estimates in ln N (OD600nm and cells mL-1 ) as a function of time.

RESULTS

The results of the kinetic modeling indicated that (T1) A1B1 = L. lactis + fructose and (T4) A2B2 = L. casei + inulin presented the best function coefficients and best fits in most cases compared to the rest. The specific growth rate of the maximum acceleration was from 0.364 to 0.473 h-1 and 0.100 to 0.129 h-1 , the concentration of bacterial cells (A) was from 0.556 to 0.713 and 0.425 to 0.548 respectively and the time where (μ) occurred with a greater magnitude (L) fluctuated between 0.854 and 0.802 and when this time in (L) is very fast, it presents values of ≤0.072 to ≤0.092. Its coefficient of determination and/or multiple regression (R2 ) obtained in the two adjustments was 0.97.

CONCLUSION

It was possible to predict the influence of the carbon source on the behavior of maximum growth rates, higher consumption due to nutrient affinity and shorter growth time. © 2023 Society of Chemical Industry.

Essential oils: An eco-friendly alternative for controlling toxigenic fungi in cereal grains

Fungi are widely disseminated in the environment and are major food contaminants, colonizing plant tissues throughout the production chain, from preharvest to postharvest, causing diseases. As a result, grain development and seed germination are affected, reducing grain quality and nutritional value. Some fungal species can also produce mycotoxins, toxic secondary metabolites for vertebrate animals. Natural compounds, such as essential oils, have been used to control fungal diseases in cereal grains due to their antimicrobial activity that may inhibit fungal growth. These compounds have been associated with reduced mycotoxin contamination, primarily related to reducing toxin production by toxigenic fungi. However, little is known about the mechanisms of action of these compounds against mycotoxigenic fungi. In this review, we address important information on the mechanisms of action of essential oils and their antifungal and antimycotoxigenic properties, recent technological strategies for food industry applications, and the potential toxicity of essential oils.

Identification of Volatile Molecules and Bioactivity of Gruyt Craft Beer Enriched with Citrus aurantium var. dulcis L. Essential Oil

In this work, for the first time, a gruyt beer and the same one after the addition of Citrus aurantium essential oil (AEO), were investigated to determine the composition of the volatile fraction. The applied analytical techniques, such as Head Space/Solid Phase Microextraction-Gas Chromatography-Mass Spectrometry (HS/SPME-GC-MS) and Proton Transfer Reaction-Time of Flight-Mass Spectrometer (PTR-ToF-MS), allowed us to identify the content of volatile organic compounds (VOCs). From the comparison between the two beer samples, it showed that the one after the addition of AEO was particularly richened in limonene and a series of minor terpene compounds. AEO was also characterized by GC/MS analysis and the results showed that limonene reached 95%. Confocal microscopy was used to look at riboflavin autofluorescence in yeast cells. It was found that beer with AEO had twice as much fluorescence intensity as the control. A spectrophotometric analysis of total polyphenols, tannins, and flavonoids, and a bioactivity screening, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azinobis-(3-Ethylbenzthiazolin-6-Sulfonic Acid) (ABTS) radical scavenger, chelating, reducing, antiglycative ones, were also carried out. Moreover, the tolerability of the tested samples in human H69 cholangiocytes and the cytoprotection towards the tert-butyl hydroperoxide (tBOOH)-induced oxidative damage were evaluated. Under our experimental conditions, the beers were found to be able to scavenge DPPH and ABTS radicals and chelate iron ions, despite weak antiglycative and reducing properties. The tested samples did not affect the viability of H69 cholangiocytes up to the highest concentrations; moreover, no signs of cytoprotection against the damage induced by tBOOH were highlighted. Adding AEO to beer resulted in a moderate enhancement of its DPPH scavenging and chelating abilities, without improvements in the other assays. Conversely, AEO and its major compound limonene were ineffective when assessed at the concentrations added to beer. This evidence suggests that the addition of AEO may enhance the organoleptic features of the beer and slightly potentiate some of its bioactivities.

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 β-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.

Carvacrol Microemulsion vs. Nanoemulsion as Novel Pork Minced Meat Active Coatings

Carvacrol is well documented for its antibacterial and antioxidant effects. However, its high volatility has directed researchers toward nanoencapsulation technology according to bioeconomy and sustainability trends. This study examined and compared free carvacrol (FC), carvacrol microemulsion (MC), carvacrol microemulsion busted with chitosan (MMC), and carvacrol nanoemulsions (NC) as active coatings on extending minced pork meat shelf life at 4 ± 1 °C for 9 days, focusing on microbiological, physiochemical, and sensory characteristics. The research involved pre-characterizing droplet sizes, evaluating antioxidants, and determining antibacterial efficacy. The results demonstrated that NC with a 21 nm droplet size exhibited the highest antioxidant and antibacterial activity. All coatings succeeded in extending the preservation of fresh minced pork meat in comparison to the free carvacrol sample (FC). The NC coating showed the highest extension of minced pork meat preservation and maintained meat freshness for 9 days, with a lower TBARs of 0.736 mg MDA/Kg, and effectively reduced mesophilic, lactic acid, and psychotrophic bacterial counts more significantly by 1.2, 2, and 1.3 log, respectively, as compared to FC. Sensory assessments confirmed the acceptability of NC and MCC coatings. Overall, the carvacrol-based nanoemulsion can be considered a novel antioxidant and antimicrobial active coating due to its demonstrated higher efficacy in all the examined tests performed.

Dried Herbs as an Easy-to-Use and Cost-Effective Alternative to Essential Oils to Extend the Shelf Life of Sheep Lump Cheese

The objective of this research was to assess the effectiveness of three specific dried herbs (rosemary, thyme, and oregano) in combating microbial spoilage in sheep lump cheese. This was achieved by comparing them with a control group and cheeses treated with corresponding 1% essential oils (Rosmarinus officinalis, Origanum vulgare, Thymus vulgaris). All cheese samples were vacuum-sealed and stored at 4 °C for 15 days. Analysis of total viable counts of viable bacteria (TVC), coliform bacteria (CB), lactic acid bacteria (LAB), and microscopic filamentous fungi (MFF) was conducted on days 0, 5, 10, and 15. The results revealed that, at the end of the storage period, dried oregano-treated samples exhibited the lowest TVC count (5.80 log CFU/g), while dried rosemary-treated samples showed the lowest CB count (3.27 log CFU/g). Moreover, the lowest MFF count (2.40 log CFU/g) was observed in oregano essential oil-treated samples. Additionally, dried oregano-treated samples displayed the highest LAB count (4.49 log CFU/g) at the experiment's conclusion. Furthermore, microorganism identification from sheep cheese was performed using MALDI-TOF MS Biotyper technology, revealing that the most frequently isolated bacteria were Citrobacter braakii and Hafnia alvei (Enterobacteriaceae family), along with Lacticaseibacillus paracasei (Lactobacillaceae family). In summary, all the natural substances examined exhibited inhibitory effects against the studied microorganisms, with oregano essential oil and dried oregano demonstrating the strongest inhibitory effects. This supports their potential use as cost-effective natural preservatives to extend the shelf life of sheep lump cheese.

Assessing the In Vitro and In Vivo Effect of Supplementation with a Garlic (Allium sativum) and Oregano (Origanum vulgare) Essential Oil Mixture on Digestibility in West African Sheep

This study assessed the impact of a mixture of garlic (Allium sativum) and oregano (Origanum vulgare) essential oils (EOGOs) on in vitro dry matter digestibility (IVDMD) and in vivo apparent nutrient digestibility. Different EOGO inclusion levels were evaluated to assess the dose response and potential effects of the mixture. Three EOGO inclusion levels (0.5, 0.75, and 1 mL/kg of incubated dry matter) were evaluated in vitro, while four treatments (0.5, 0.75, and 1 mL/day of EOGO and a control group) were tested in vivo on 12 West African sheep. A randomized controlled trial was conducted using a 4 × 4 design. Blood parameters (glucose, blood urea nitrogen, and β-hydroxybutyrate) were measured to observe the effect of EOGO on the metabolism. The results showed that the inclusion of EOGO significantly enhanced IVDMD at low levels (p < 0.052) compared with the highest levels in treatments containing 0.5 and 0.75 mL/kg of EOGO dry matter. A higher intake of dry matter (DM), crude protein (CP), and neutral detergent fiber (NDF) (p < 0.05) was observed in the in vivo diets with the inclusion of EOGO. In terms of in vivo apparent digestibility, significant differences were found among treatments in the digestibility coefficients of DM, CP, and NDF. EOGO inclusion increased the digestibility of DM. CP digestibility displayed a cubic effect (p < 0.038), with the lowest values of digestibility observed at 1 mL EOGO inclusion. Additionally, NDF digestibility showed a cubic effect (p < 0.012), with the highest value obtained at 0.75 mL of EOGO inclusion. The inclusion levels above 0.75 mL EOGO showed a cubic effect, which indicates that higher concentrations of EOGO may not be beneficial for the digestibility of CP and NDF. Although no significant difference was observed in total digestible nutrients, a linear trend was observed (p < 0.059). EOGO improved the intake of DM, CP, and NDF. EOGO supplementation improved the digestibility of DM and NDF, with optimal levels observed at 0.5 mL/day. No significant effects were observed in the blood parameters. These results suggest that EOGO has the potential as an additive in ruminal nutrition to improve food digestibility and serve as an alternative to antibiotic additives. The use of EOGO potentially improves fiber digestion and may reduce the use of antibiotics in livestock production. Garlic (A. sativum) and oregano (O. vulgare) essential oils effectively modulated fiber digestibility at 0.75 mL/day. Garlic (A. sativum) and oregano (O. vulgare) essential oils have the potential to improve digestibility at low inclusion levels and serve as an alternative to antibiotic additives. The effectiveness of essential oils is greater in a mixture and at lower doses.

Analysis of the volatile monoterpene composition of citrus essential oils by photoelectron spectroscopy employing continuously monitored dynamic headspace sampling

A new photoelectron spectroscopic method permitting a quantitative analysis of the volatile headspace of several essential oils is presented and discussed. In particular, we focus on the monoterpene compounds, which are known to be the dominant volatile components in many such oils. The photoelectron spectra of the monoterpene constituents may be effectively isolated by accepting for analysis only those electrons that accompany the production of m/z = 136 ions, and by using low photon energies that restrict cation fragmentation. The monoterpene isomers are then identified and quantified by regression modelling using a library of terpene standard spectra. An advantage of this approach is that pre-concentration of the volatile vapour is not required, and all steps are performed at ambient temperature, avoiding the possible deleterious effects (such as isomerisation/decomposition) that may sometimes arise in gas chromatographic (GC) procedures. As a proof-of-principle demonstration, three citrus oils (lemon, lime, bergamot) are analysed with this approach and the results are compared with reported GC composition profiles obtained for these oils. Potential advantages of the methodology that include multiplex detection and real-time, in situ analysis are identified and discussed. Alternative and faster experimental implementations concerning laboratory-based ionization and detection schemes are proposed and considered, as is the possibility of a straightforward extension towards simultaneous determination of enantiomeric excesses.

Use of Doehlert Matrix as a Tool for High-Throughput Screening of Organic Acids and Essential Oils on Miniaturized Pork Loins, Followed by Lab-Scale Validation That Confirmed Tested Compounds Do Not Show Synergistic Effects against Salmonella Typhimurium

The many possible treatments and continuously changing consumer trends present a challenge when selecting antimicrobial interventions during pork processing. Thirty-five potential antimicrobials were screened at commercial working concentrations by individually adding them to miniaturized (69 cm3) disks of pork loin ends, followed by inoculation with Salmonella Typhimurium ATCC 19585. Two organic acids and nine essential oils significantly inhibited Salmonella counts on pork (p < 0.05). However, six compounds that represent different levels of significance (p < 0.05-p < 0.0001) were selected as independent variables to build a Response Surface Methodology model based on a Doehlert matrix (Doehlert Matrix-RSM): lactic acid 1.25%, formic acid 0.25%, cumin 0.25%, clove 0.25%, peppermint 0.5%, and spearmint 0.5%. The goal of the Doehlert Matrix-RSM was to study single and paired effects of these antimicrobials on the change in Salmonella over 24 h. The Doehlert Matrix-RSM model predicted that lactic acid, formic acid, cumin, peppermint, and spearmint significantly reduced Salmonella when added alone, while no significant interactions between these antimicrobials were found. A laboratory-scale validation was carried out on pork loin end slices, which confirmed the results predicted by the model. While this screening did not identify novel synergistic combinations, our approach to screening a variety of chemical compounds by implementing a miniaturized pork loin disk model allowed us to identify the most promising antimicrobial candidates to then formally design experiments to study potential interactions with other antimicrobials.

Can droplet size influence antibacterial activity in ultrasound-prepared essential oil nanoemulsions?

Essential oil nanoemulsion may have improved antibacterial properties over pure oil and can be used for food preservation. Ultrasonic cavitation is the most common mechanism for producing nanoemulsions, and the impact of processing parameters on droplet properties needs to be elucidated. A systematic literature search was performed in four databases (Science Direct, Web of Science, Scopus and PubMed), and 987 articles were found, 16 of which were eligible for the present study. A meta-analysis was performed to qualitatively assess which process parameters (power, sonication time, essential oil, and tween 80 concentration) can influence the final droplet size and polydispersity and how droplet size is associated with antibacterial activity. We observed that power, essential oil, and tween 80 concentrations added during processing are the critical variables for forming smaller droplets. Ratios of up to 3:1 (surfactant:oil) can produce droplets smaller than 180 nm with antibacterial properties superior to pure oil or isolated compounds. The improved properties of nanoemulsions are associated with the size and chemical composition of the droplet since the proportion of the hydrophobic core (EO) and the hydrophilic outer layer (Tween 80) directly influences the antibacterial mechanism of action.

Current status, technology, regulation and future perspectives of essential oils usage in the food and drink industry

Nowadays, essential oils (EOs) have a wide use in many applications such as in food, cosmetics, pharmaceutical and animal feed products. Consumers' preferences concerning healthier and safer foodstuffs lead to an increased demand for natural products, in replacement of synthetic substances, used as preservatives, flavourings etc. EOs, besides being safe, are promising alternatives as natural food additives, and much research has been carried out on their antioxidant and antimicrobial activity. The initial purpose of this review is to discuss conventional and 'green' extraction techniques along with their basic mechanism for the isolation of EOs from aromatic plants. This review aims to provide a broad overview of the current knowledge about the chemical constitution of EOs while considering the existence of different chemotypes, since bioactivity is attributed to the chemical composition - qualitative and quantitative - of EOs. Although the food industry primarily uses EOs as flavourings, an overview on recent applications of EOs in food systems and active packaging is provided. EOs exhibit poor solubility in water, oxidation susceptibility, negative organoleptic effect and volatility, restricting their use. Encapsulation techniques have been proven to be one of the best approaches to preserve the biological activities of EOs and minimize their effects on food sensory qualities. Herein, different encapsulation techniques and their basic mechanism for loading EOs are discussed. EOs are highly accepted by consumers, who are often under the misconception that 'natural' means safe. This is, however, an oversimplification, and the possible toxicity of EOs should be taken into consideration. Thus, in the final section of the current review, the focus is on current EU legislation, safety assessment and sensory evaluation of EOs. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Effects of grafting methods and raw materials on the physicochemical properties and biological activities of phenolic acids grafted oat β-glucan

Phenolic acids are commonly used as food biological preservatives. Grafting phenolic acids onto polysaccharides could effectively enhance their biological activities and environmental stability to varying degrees. However, grafting methods and raw materials could affect the physical properties and biological activities of the phenolic acid-grafted polysaccharides. In this study, caffeic acid (CA) and gallic acid (GA) were grafted onto oat β-glucan (OG) and hydrolyzed oat β-glucan (OGH) through N,N'-carbonyldiimidazole-mediated (CDI) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride coupling N-hydroxysuccinimide (EDC/NHS) methods. Graft modification decreased the crystallinity and thermal stability of the conjugates, but retained good bioactivities for the conjugates. The antioxidant and bacteriostatic activities of the conjugates prepared by the EDC method were better than those of the CDI method, and the OGH-conjugates showed better biological activities than OG-conjugates. EDC-GAOGH showed best DPPH (89.78%) and ABTS (92.32%) scavenging activities. The inhibitory effect of EDC-GAOGH on Escherichia coli was significantly better than that of EDC-CAOGH, but for Staphylococcus aureus, the results are opposite, which indicating that different phenolic acid grafting products have different inhibitory effects on pathogenic microbes. In general, grafting phenolic acids onto OGH using EDC method is an effective strategy for preparing food biological preservative.

Diet of Broilers with Essential Oil from Citrus sinensis and Xylopia aromatica Fruits

This study aimed to evaluate the effects of essential oils from the fruits of Citrus sinensis and Xylopia aromatica, included in broiler feed, on blood parameters, the biometrics of digestive organs, bone analyses, and the biochemical profiles of the viscera, as well as the histomorphometry of the small intestine. In this study, 180 one-day-old male chicks of the Cobb 500 strain were fed a corn and soybean meal over three treatments and six replications, and the experimental design was completely randomized. The data were subjected to an analysis of variance and a Tukey test at a 5% significance level. The effect of the experimental diets on performance, blood parameters, biometrics of the digestive organs, bone analysis, and biochemical profiles of the viscera, as well as the histomorphometry of the small intestine, were evaluated. The compounds identified in the essential oil of X. aromatica were sylvestrene, α-pinene, and β-pinene, while in C. sinensis they were limonene and myrcene. The essential oils of C. sinensis and X. aromatica had no significant effect on performance at 14 days. The effects of the presence of the essential oils of C. sinensis and X. aromatica on the response were beneficial: there were reductions in liver lipids, cholesterol, and triglycerides, and in the depths of the crypts in the jejunum of chickens. So, the essential oils from the fruits of C. sinensis and X. aromatica can be used in broiler chickens to improve the lipid profiles of birds without affecting their performance.

Date (Phoenix dactylifera L.) seed oil is an agro-industrial waste with biopreservative effects and antimicrobial activity

Antimicrobial resistant (AMR) infections are a leading health threat globally. Previous literature has underscored the farm-to-fork continuum as a potential focal point for the emergence and spread of AMR. In the present study, date (Phoenix dactylifera L.) seed oil was investigated for its chemical composition and antimicrobial activity against common foodborne pathogens including Escherichia coli O157:H7, Salmonella enteritidis, Salmonella typhimurium, Listeria monocytogenes, and Staphylococcus aureus in vitro, and in ultra-high-temperature (UHT) milk as a food model at storage temperatures of 37 °C (24 h) and 10 °C (7 days). GC-MS analysis of the seed oil revealed 20 compounds, with octadecane (52.2-55.4%) as the major constituent, and the fatty acid analysis revealed 17 fatty acids, with oleic acid (42.3-43.1%) as the main constituent, followed by lauric acid (19.8-20.3%). The antimicrobial activity of date seed oil was determined using the microdilution method. A significant inhibition against gram-negative bacteria was noted in microbiological media and UHT milk, with a log reduction ranging from 4.3 to 6.7 (at 37 °C/24 h) and 5.7 to 7.2 (at 10 °C/7 days), respectively, at oil concentrations ranging between 10 and 15 µl/ml. The oil showed a similar significant inhibitory effect against St. aureus in the microbiological media (2.0-6.0 log reduction), whereas the inhibitory effect against L. monocytogenes was not statistically significant, with a maximum log reduction of 0.64 achieved at a concentration of 10 µl/ml. AFM imaging of the bacteria showed that oil treatment led to morphological changes in the bacteria including the formation of distorted shapes, surface blebs, indentations, stiffness, and swelling. Present findings suggest that date seed oil can be a promising by-product with potential antimicrobial activity and a food preservative.

A review of the bioactive properties of Mongolian plants, with a focus on their potential as natural food preservatives

Consumers have recently preferred food that is easy to make and of excellent quality, as well as food that is safe, natural, and minimally processed, but has a longer shelf life. Food deteriorates over time as a result of microbiological, chemical, or physical changes. Phytochemicals derived from medicinal and food plants have long been recognized for their biological activity to protect plants. These bioactivities are designed to increase the shelf life of food while inhibiting the growth of microorganisms. The use of natural plant food preservatives containing bioactive compounds as health-promoting agents is particularly intriguing. Furthermore, due to their effectiveness against food spoilage and foodborne pathogens, natural plant-origin antimicrobial compounds have been investigated as alternatives to synthetic antimicrobial compounds for preserving food quality. This review focused on the plant composition and properties that can be utilized as a natural food preservative, as well as the possibilities of using Mongolian medicinal plants.

Edible Coatings as a Natural Packaging System to Improve Fruit and Vegetable Shelf Life and Quality

In the past years, consumers have increased their interest in buying healthier food products, rejecting those products with more additives and giving preference to the fresh ones. Moreover, the current environmental situation has made society more aware of the importance of reducing the production of plastic and food waste. In this way and considering the food industry's need to reduce food spoilage along the food chain, edible coatings have been considered eco-friendly food packaging that can replace traditional plastic packaging, providing an improvement in the product's shelf life. Edible coatings are thin layers applied straight onto the food material's surface that are made of biopolymers that usually incorporate other elements, such as nanoparticles or essential oils, to improve their physicochemical properties. These materials must provide a barrier that can prevent the passage of water vapor and other gasses, microbial growth, moisture loss, and oxidation so shelf life can be extended. The aim of this review was to compile the current data available to give a global vision of the formulation process and the different ways to improve the characteristics of the coats applied to both fruits and vegetables. In this way, the suitability of compounds in by-products produced in the food industry chain were also considered for edible coating production.

Antimicrobial Effects and Antioxidant Activity of Myrtus communis L. Essential Oil in Beef Stored under Different Packaging Conditions

The aim of this study was to assess the antimicrobial effects of myrtle (Myrtus communis L.) essential oil (EO) on pathogenic (E. coli O157:H7 NCTC 12900; Listeria monocytogenes ATCC BAA-679) and spoilage microbiota in beef and determine its minimum inhibitory concentration (MIC) and antioxidant activity. The behavior of LAB, Enterobacteriaceae, Pseudomonas spp., and fungi, as well as total mesophilic (TM) and total psychotropic (TP) counts, in beef samples, was analyzed during storage at 2 and 8 °C in two different packaging systems (aerobiosis and vacuum). Leaves of myrtle were dried, its EO was extracted by hydrodistillation using a Clevenger-type apparatus, and the chemical composition was determined using chromatographical techniques. The major compounds obtained were myrtenyl acetate (15.5%), β-linalool (12.3%), 1,8-cineole (eucalyptol; 9.9%), geranyl acetate (7.4%), limonene (6.2%), α-pinene (4.4%), linalyl o-aminobenzoate (5.8%), α-terpineol (2.7%), and myrtenol (1.2%). Myrtle EO presented a MIC of 25 µL/mL for E. coli O157:H7 NCTC 12900, E. coli, Listeria monocytogenes ATCC BAA-679, Enterobacteriaceae, and E. coli O157:H7 ATCC 35150 and 50µL/mL for Pseudomonas spp. The samples packed in aerobiosis had higher counts of deteriorative microorganisms than samples packed under vacuum, and samples with myrtle EO presented the lowest microbial contents, indicating good antimicrobial activity in beef samples. Myrtle EO is a viable natural alternative to eliminate or reduce the pathogenic and deteriorative microorganisms of meat, preventing their growth and enhancing meat safety.

Edible Coatings and Future Trends in Active Food Packaging-Fruits' and Traditional Sausages' Shelf Life Increasing

The global food production industry faces environmental concerns exacerbated by substantial food waste. European countries are striving to reduce food waste towards a circular bioeconomy and sustainable development. To address environmental issues and reduce plastic waste, researchers are developing sustainable active packaging systems, including edible packaging made from industry residues. These innovations aim to increase food safety and quality, extend shelf life, and reduce plastic and food waste. Particularly important in the context of the growing demand for fresh and minimally processed fruits, edible coatings have emerged as a potential solution that offers numerous advantages in maintaining fruit quality. In addition to fruit, edible coatings have also been investigated for animal-based foods to meet the demand for high-quality, chemical-free food and extended shelf life. These products globally consumed can be susceptible to the growth of harmful microorganisms and spoilage. One of the main advantages of using edible coatings is their ability to preserve meat quality and freshness by reducing undesirable physicochemical changes, such as color, texture, and moisture loss. Furthermore, edible coatings also contribute to the development of a circular bioeconomy, promoting sustainability in the food industry. This paper reviews the antimicrobial edible coatings investigated in recent years in minimally processed fruits and traditional sausages. It also approaches bionanocomposites as a recently emerged technology with potential application in food quality and safety.

Antibacterial activity and mechanism of cinnamon essential oil nanoemulsion against Pseudomonas deceptionensis CM2

This work aimed to evaluate the antibacterial activity and mechanism of cinnamon essential oil nanoemulsion (CON) against Pseudomonas deceptionensis CM2. The results revealed that CON could effectively inhibit the proliferation of P. deceptionensis CM2 cells in a time- and concentration-dependent manner. After 4 h of incubation with CON at the minimum inhibitory concentration (0.125 mg/mL), the relative fluorescence intensity of propidium iodide and 1-N-phenylnapthylamine (NPN) was increased by 32.0% and 351.4%, respectively. The membrane permeability of P. deceptionensis CM2 cells was significantly disrupted after CON treatment, resulting in the leakage of intracellular substances (such as proteins and electrolytes). CON also caused significant increases in the DiBAC4(3) fluorescence intensity of P. deceptionensis CM2 cells. These results demonstrate that CON induced inactivation of P. deceptionensis CM2 by destroying the integrity and function of bacterial membrane. A higher level of intracellular reactive oxygen species (ROS) was observed in CON-treated cells (p < 0.05), compared with control cells. Moreover, the addition of glutathione to the growth medium remarkably decreased the antimicrobial activity of CON against P. deceptionensis CM2, further confirming that oxidative stress played an important role in the antimicrobial activity of CON. Overall, CON may exhibit antibacterial effects by causing damage to the bacterial membranes and oxidative stress.

Multiple potential strategies for the application of nisin and derivatives

Nisin is a naturally occurring bioactive small peptide produced by Lactococcus lactis subsp. lactis and belongs to the Type A (I) lantibiotics. Due to its potent antimicrobial activity, it has been broadly employed to preserve various food materials as well as to combat a variety of microbial pathogens. The present review discusses the antimicrobial properties of nisin and different types of their derivatives employed to treat microbial pathogens with a detailed underlying mechanism of action. Several alternative strategies such as combination, conjugation, and nanoformulations have been discussed in order to address several issues such as rapid degradation, instability, and reduced activity due to the various environmental factors that arise in the applications of nisin. Furthermore, the evolutionary relationship of many nisin genes from different nisin-producing bacterial species has been investigated. A detailed description of the natural and bioengineered nisin variants, as well as the underlying action mechanisms, has also been provided. The chemistry used to apply nisin in conjugation with natural or synthetic compounds as a synergetic mode of antimicrobial action has also been thoroughly discussed. The current review will be useful in learning about recent and past research that has been performed on nisin and its derivatives as antimicrobial agents.

Recent advancements on use of essential oils as preservatives against fungi and mycotoxins spoiling food grains

Spoilage of grains by mycotoxigenic fungi poses a great threat to food security and human health. Conventionally used chemical agents to prevent grain fungi contamination cause increasingly significant problems such as microbial resistance, residual toxicity and environmental unfriendliness. In recent years, plant essential oils (EOs) have become a hot spot in the research of control of grain fungi and mycotoxins, due to their extensive sources, non-toxicity, environmental friendliness and good antifungal efficiency. The current review aims to provide an overview of the prevention of fungi and mycotoxins in grain through EOs. The antifungal and toxin inhibition efficiency of different EOs and their effective components are investigated. The inhibition mechanism of EOs on fungi and mycotoxins in grains is introduced. The influence of EOs treatment on the change of grain quality is also discussed. In addition, the formulations and techniques used to overcome the disadvantages of EOs application are introduced. The results of recent studies have confirmed that EOs provide great potential for controlling common fungi and mycotoxins in grains, and enhancing quantity and quality safety of grains.

Carvacrol/β-cyclodextrin inclusion complex as a fumigant to control decay caused by Penicillium digitatum on Shatangju mandarin slices

Preservation and microorganism control of fresh-cut fruit pose a persistent challenge in the food industry. To address this issue, we prepared a β-cyclodextrin (β-CD) inclusion complex containing carvacrol using a coprecipitation method and employed it for the non-contact fumigation of fresh-cut Shatangju mandarin slices. This biodegradable and safe preservative offers an effective means to combat spoilage and ensure product quality. We confirmed the formation of the encapsulated structure of the inclusion complex through various characterization methods, including scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). We also demonstrated the inhibitory effect of this preservative on Penicillium digitatum and its associated spoilage both in vitro and in vivo. The incidence and severity were significant lower in the inclusion complex-treated group (75.0% and 46.7%, respectively) compared to the group treated with pure carvacrol (100% and 69.2%, respectively). In addition, fruit freshness parameters and sensory evaluation showed that the inclusion complex treatment effectively maintained the overall quality of the fruit and achieved the highest consumer acceptance.

Plant extracts and essential oils in the dairy industry: A review

Plants have been used as food additives worldwide to enhance the sensory qualities of foods and extend their shelf life by reducing or eliminating foodborne pathogens. They also serve as therapeutic agents due to their beneficial effects on human health through their anti-cancerous, anti-inflammatory, antioxidant, and immune-modulatory properties. Plants can be added to food as a dry powder, grated material, paste, juice, or as an extract that can be produced by a variety of methods. Plant extracts and essential oils are concentrated sources of bioactive phytochemicals that can be added to food in small amounts in a variety of forms. These forms include liquid, semi-solid, or dry powder for easy and uniform diffusion. Encapsulation can protect bioactive compounds from temperature, moisture, oxidation, and light, as well as allow for controlling the release of the encapsulated ingredients. Nanoemulsions can enhance the bioactivity of active components. This review explains how plant extracts and essential oils are used in the dairy industry as antimicrobial materials, analyzing their impact on starter bacteria; as natural antioxidants to prevent the development of off-flavors and increase shelf life; and as technological auxiliaries, like milk-clotting enzymes, stabilizers, and flavoring agents. Therefore, plant extracts and essential oils are a better choice for the dairy industry than plants or their parts due to a wide range of applications, homogeneous dispersion, and ability to control the concentration of the bioactive ingredients and enhance their efficiency.

Citral and trans-cinnamaldehyde, two plant-derived antimicrobial agents can induce Staphylococcus aureus into VBNC state with different characteristics

Viable but nonculturable (VBNC) state bacteria are difficult to detect in the food industry due to their nonculturable nature and their recovery characteristics pose a potential threat to human health. The results of this study indicated that S. aureus was found to enter the VBNC state completely after induced by citral (1 and 2 mg/mL) for 2 h, and after induced by trans-cinnamaldehyde (0.5 and 1 mg/mL) for 1 h and 3 h, respectively. Except for VBNC state cells induced by 2 mg/mL citral, the VBNC state cells induced by the other three conditions (1 mg/mL citral, 0.5 and 1 mg/mL trans-cinnamaldehyde) were able to be resuscitated in TSB media. In the VBNC state cells induced by citral and trans-cinnamaldehyde, the ATP concentration was reduced, the hemolysin-producing ability was significantly decreased, but the intracellular ROS level was elevated. The results of heat and simulated gastric fluid experiments showed different environment resistance on VBNC state cells induced by citral and trans-cinnamaldehyde. In addition, by observing the VBNC state cells showed that irregular folds on the surface, increased electron density inside and vacuoles in the nuclear region. What's more, S. aureus was found to enter the VBNC state completely after induced by meat-based broth containing citral (1 and 2 mg/mL) for 7 h and 5 h, after induced by meat-based broth containing trans-cinnamaldehyde (0.5 and 1 mg/mL) for 8 h and 7 h. In summary, citral and trans-cinnamaldehyde can induce S. aureus into VBNC state and food industry needs to comprehensively evaluate the antibacterial capacity of these two plant-derived antimicrobial agents.

Carvacrol-loaded nanoemulsions produced with a natural emulsifier for lettuce sanitization

Carvacrol is an antimicrobial agent that shows potential for eliminating microorganisms in vegetables, increasing food safety. However, intense odor and low water solubility of carvacrol are limiting factors for its application for fresh vegetables sanitization, which can be overcome by nanotechnology. Two different nanoemulsions containing carvacrol (11 mg/mL) were developed by probe sonication: carvacrol-saponin nanoemulsion (CNS) and carvacrol-polysorbate 80 nanoemulsion (CNP). Formulations presented appropriate droplet sizes (from 74.7 nm to 168.2 nm) and high carvacrol encapsulation efficiency (EE) (from 89.5 % to 91.5 %). CNS showed adequate droplet size distribution (PDI < 0.22) and high zeta potential values (around -30 mV) compared to CNP, with saponin chosen for the following experiments. Carvacrol nanoemulsions presented Bacterial Inactivation Concentration (BIC) against the Salmonella cocktail from 5.51 to 0.69 mg/mL and for the E. coli cocktail from 1.84 to 0.69 mg/mL. Among all tested nanoemulsions, CNS1 presented the lowest BIC (0.69 mg/mL) against both bacterial cocktails. Damage to bacterial cells in lettuce treated with nanoemulsion was confirmed by scanning electron microscopy. For lettuce sanitization, CNS1 showed a similar effect to unencapsulated carvacrol, with a high bacterial reduction (>3 log CFU/g) after lettuce immersion for 15 min at 2 × BIC. Using the same immersion time, the CNS1 (2 × BIC) demonstrated equal or better efficacy in reducing both tested bacterial cocktails (>3 log CFU/g) when compared to acetic acid (6.25 mg/mL), citric acid (25 mg/mL), and sodium hypochlorite solution (150 ppm). Lettuce immersed in CNS1 at both concentrations (BIC and 2 × BIC) did not change the color and texture of leaves, while the unencapsulated carvacrol at 2 × BIC darkened them and reduced their firmness. Consequently, carvacrol-saponin nanoemulsion (CNS1) proved to be a potential sanitizer for lettuce.

Inhibitive effect and mechanism of cinnamaldehyde on growth and OTA production of Aspergillus niger in vitro and in dried red chilies

Mould and mycotoxin contamination is an ongoing issue in agriculture and food industry. Production by Aspergillus niger DTZ-12 in Guizhou dried red chilies was found, leading to significant economic losses. In this study, the inhibitive efficacy (Effective Concentration, EC) of cinnamaldehyde (CIN), eugenol (EUG), carvacrol (CAR), and linalool (LIN) against A. niger DTZ-12 were evaluated. CIN with the best antifungal capacity was then investigated for the comprehensive inhibitory activity against A. niger DTZ-12 including mycelia, spores, and physiological activities. Results showed that CIN can effectively retard mycelial growth, spore germination, and OTA production of A. niger DTZ-12 in vitro and in dried red chilies during storage. At physiological level, CIN can increase cell membrane permeability by reducing the ergosterol, decrease ATP content and ATPase activity, and promote the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in cell. These results suggested that CIN displayed a great potential to be employed as a natural and effective alternative preservative during dried red chili storage.

Zerumbone Disturbs the Extracellular Matrix of Fluconazole-Resistant Candida albicans Biofilms

This study assessed the effect of zerumbone (ZER) against fluconazole-resistant (CaR) and -susceptible Candida albicans (CaS) biofilms and verified the influence of ZER on extracellular matrix components. Initially, to determine the treatment conditions, the minimum inhibitory concentration (MIC), the minimum fungicidal concentration (MFC) and the survival curve were evaluated. Biofilms were formed for 48 h and exposed to ZER at concentrations of 128 and 256 µg/mL for 5, 10 and 20 min (n = 12). One group of biofilms did not receive the treatment in order to monitor the effects. The biofilms were evaluated to determine the microbial population (CFU/mL), and the extracellular matrix components (water-soluble polysaccharides (WSP), alkali-soluble polysaccharides (ASPs), proteins and extracellular DNA (eDNA), as well as the biomass (total and insoluble) were quantified. The MIC value of ZER for CaS was 256 μg/mL, and for CaR, it was 64 μg/mL. The survival curve and the MFC value coincided for CaS (256 μg/mL) and CaR (128 μg/mL). ZER reduced the cellular viability by 38.51% for CaS and by 36.99% for CaR. ZER at 256 µg/mL also reduced the total biomass (57%), insoluble biomass (45%), WSP (65%), proteins (18%) and eDNA (78%) of CaS biofilms. In addition, a reduction in insoluble biomass (13%), proteins (18%), WSP (65%), ASP (10%) and eDNA (23%) was also observed in the CaR biofilms. ZER was effective against fluconazole-resistant and -susceptible C. albicans biofilms and disturbed the extracellular matrix.

New preservation and detection technologies for edible mushrooms: A review

Edible mushrooms are nutritious, tasty, and have medicinal value, which makes them very popular. Fresh mushrooms have a high water content and a crisp texture. They demonstrate strong metabolic activity after harvesting. However, they are prone to textural changes, microbial infestation, and nutritional and flavor loss, and they therefore require appropriate post-harvest processing and preservation. Important factors affecting safety and quality during their processing and storage include their quality, source, microbial contamination, physical damage, and chemical residues. Thus, these aspects should be tested carefully to ensure safety. In recent years, many new techniques have been used to preserve mushrooms, including electrofluidic drying and cold plasma treatment, as well as new packaging and coating technologies. In terms of detection, many new detection techniques, such as nuclear magnetic resonance (NMR), imaging technology, and spectroscopy can be used as rapid and effective means of detection. This paper reviews the new technological methods for processing and detecting the quality of mainstream edible mushrooms. It mainly introduces their working principles and application, and highlights the future direction of preservation, processing, and quality detection technologies for edible mushrooms. Adopting appropriate post-harvest processing and preservation techniques can maintain the organoleptic properties, nutrition, and flavor of mushrooms effectively. The use of rapid, accurate, and non-destructive testing methods can provide a strong assurance of food safety. At present, these new processing, preservation and testing methods have achieved good results but at the same time there are certain shortcomings. So it is recommended that they also be continuously researched and improved, for example through the use of new technologies and combinations of different technologies. © 2023 Society of Chemical Industry.

Synergistic effect of nano zinc oxide and tea tree essential oil on the properties of soluble soybean polysaccharide films

Soluble soybean polysaccharide (SSPS)-based composite films with the addition of nano zinc oxide (nZnO, 5 wt% based on SSPS) and tea tree essential oil (TTEO, 10 wt% based on SSPS) were developed by the casting method. The effect of the combination of nZnO and TTEO on the microstructure and physical, mechanical and functional properties of SSPS films was evaluated. The results showed that the SSPS/TTEO/nZnO film exhibited enhanced water vapor barrier properties, thermal stability, water resistance, surface wettability, and total color difference, and almost completely prevented ultraviolet light transmission. The addition of TTEO and nZnO had no significant effect on the tensile strength and elongation at break of the films, but decreased the percentage of light transmittance of the films at 600 nm from 85.5 % to 10.1 %. The DPPH radical scavenging activity of the films significantly increased from 46.8 % (SSPS) to 67.7 % (SSPS/TTEO/nZnO) due to the presence of TTEO. Scanning electron microscopy analysis indicated that nZnO and TTEO were evenly dispersed in the SSPS matrix. The synergistic effect of nZnO and TTEO endowed the SSPS film with excellent antibacterial activity against E. coli and S. aureus, suggesting that the SSPS/TTEO/nZnO film could be a promising material for active packaging applications.

Cinnamaldehyde-Contained Polymers and Their Biomedical Applications

Cinnamaldehyde, a natural product that can be extracted from a variety of plants of the genus Cinnamomum, exhibits excellent biological activities including antibacterial, antifungal, anti-inflammatory, and anticancer properties. To overcome the disadvantages (e.g., poor water solubility and sensitivity to light) or enhance the advantages (e.g., high reactivity and promoting cellular reactive oxygen species production) of cinnamaldehyde, cinnamaldehyde can be loaded into or conjugated with polymers for sustained or controlled release, thereby prolonging the effective action time of its biological activities. Moreover, when cinnamaldehyde is conjugated with a polymer, it can also introduce environmental responsiveness to the polymer through the form of stimuli-sensitive linkages between its aldehyde group and various functional groups of polymers. The environmental responsiveness provides the great potential of cinnamaldehyde-conjugated polymers for applications in the biomedical field. In this review, the strategies for preparing cinnamaldehyde-contained polymers are summarized and their biomedical applications are also reviewed.

Molecular Structure, Electronic Properties, Reactivity (ELF, LOL, and Fukui), and NCI-RDG Studies of the Binary Mixture of Water and Essential Oil of Phlomis bruguieri

Essential oils are volatile oil-like liquids with a characteristic strong smell and taste. They are formed in plants and are then extracted. Essential oils have extremely strong physiological and pharmacological properties, which are used in the medicine, cosmetics, and food industries. In this study, the molecules caryophyllene oxide, β-pinene, 1,8-cineol, α-cubebene, and β-caryophyllene, which are the molecules with the highest contents in the essential oil of the plant mentioned in the title, were selected and theoretical calculations describing their interactions with water were performed. Because oil–water mixtures are very important in biology and industry and are ubiquitous in nature, quantum chemical calculations for binary mixtures of water with caryophyllene oxide, β-pinene, 1,8-cineol, α-cubebene, and β-caryophyllene were performed using the density functional theory (DFT)/B3LYP method with a basis of 6–31 G (d, p). Molecular structures, HOMO–LUMO energies, electronic properties, reactivity (ELF, LOL, and Fukui), and NCI-RDG and molecular electrostatic potential (MEP) on surfaces of the main components of Phlomis bruguieri Desf. essential oil were calculated and described.

Incorporation of betel leaf extract provides oxidative stability and improves phytochemical, textural, sensory and antimicrobial activities of buffalo meat sausages

The antioxidant effect of betel leaf extract (BLE) on lipid and protein oxidation, microbial count and physicochemical attributes was investigated in meat sausages during refrigerated storage at 4 ± 1 °C. Buffalo meat sausages were developed after incorporating 0, 250, 500 and 750 mg kg^-1 of BLE (BLE0, BLE1, BLE2 and BLE3) respectively. The sausages showed no changes in proximate composition due to BLE inclusion, but there was an improvement in microbial quality, color score, textural properties and lipid and protein oxidative stability. Further, higher sensory scores were observed for the BLE-incorporated samples. The images from scanning electron microscopy (SEM) revealed a reduction in surface roughness and unevenness showing microstructure modification in BLE treated sausages compared to the control sausages. Hence, to improve the storage stability and impede the rate of lipid oxidation in sausages, BLE incorporation proved to be an effective strategy.

Liposomal Encapsulated Oregano, Cinnamon, and Clove oils Enhanced the performance, bacterial metabolites Antioxidant potential, and Intestinal microbiota of Broiler Chickens

Encapsulated phytochemicals with augmented therapeutic and nutritional characteristics have become promising alternatives to antimicrobials in the poultry industry. Hence, our key target was to explore the efficacy of liposomal encapsulation, as a novel carrier, for essential oils (LEOs) on growth, digestibility, intestinal microbiota, and bacterial metabolites of broiler chickens. Moreover, the impact of encapsulated EOs on transcription mechanisms targeting the genes encoding digestive enzymes, gut barrier functions and antioxidant potential of broiler chickens was evidenced. Four equal broiler groups were fed 4 basal diets fortified with LEOs (oregano, cinnamon, and clove) at the levels of 0, 200, 300, and 400 mg/kg diet. Our findings revealed significant improvement in body weight gain and feed conversion ratio of birds fed higher levels of LEOs. These results came concurrently with increasing the activities of digestive enzymes at both serum and molecular levels and consequently nutrient digestibility (dry matter, ether extract, crude protein, and crude fiber) in these groups. Remarkably, the abundance of beneficial bacteria as well as the bacterial metabolites (valeric acid, butyric acid, propionic acid, acetic acid, and total short-chain fatty acids) was increased, while that of pathogenic ones was reduced following dietary inclusion of LEOs. Of note, the mRNA expression of genes encoding antioxidant stability [catalase (CAT), superoxide dismutase 1 (SOD-1), glutathione peroxidase 1 (GPX-1), nuclear factor erythroid 2-related factor 2 (NRF2), NAD(P)H dehydrogenase quinone 1 (NQO1), and heme oxygenase-1 (HO-1)] as well as barrier functions [mucin-2 (MUC-2)] and tight junction proteins, TJP [junctional adhesion molecule-2 (JAM-2) and occludin] were noticeably upregulated in broilers fortified with 400 mg/kg diet of LEOs. Overall, the present work recommended dietary inclusion of LEOs as beneficial additives for attaining targeted performance, gut health and antioxidant stability in poultry farming.

Antibacterial and Antibiofilm Efficacy of Thyme (Thymus vulgaris L.) Essential Oil against Foodborne Illness Pathogens, Salmonella enterica subsp. enterica Serovar Typhimurium and Bacillus cereus

Nowadays, the wide spread of foodborne illness and the growing concerns about the use of synthetic food additives have shifted the focus of researchers towards essential oils (EOs) as possible antimicrobials and preservatives of natural origin. Thanks to their antimicrobial properties against pathogenic and food spoilage microorganisms, EOs have shown good potential for use as alternative food additives, also to counteract biofilm-forming bacterial strains, the spread of which is considered to be among the main causes of the increase in foodborne illness outbreaks. In this context, the aim of this study has been to define the antibacterial and antibiofilm profile of thyme (Thymus vulgaris L.) essential oil (TEO) against widespread foodborne pathogens, Salmonella enterica subsp. enterica serovar Typhimurium and Bacillus cereus. TEO chemical composition was analyzed through gas chromatography-mass spectrometry (GC-MS). Preliminary in vitro antibacterial tests allowed to qualitatively verify TEO efficacy against the tested foodborne pathogens. The subsequent determination of minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values allowed to quantitatively define the bacteriostatic and bactericidal effects of TEO. To evaluate the ability of essential oils to inhibit biofilm formation, a microplate assay was performed for the bacterial biofilm biomass measurement. Results suggest that TEO, rich in bioactive compounds, is able to inhibit the growth of tested foodborne bacteria. In addition, the highlighted in vitro anti-biofilm properties of TEO suggest the use of this natural agent as a promising food preservative to counteract biofilm-related infections in the food industry.

Antimicrobial Activity of Gelatin Nanofibers Enriched by Essential Oils against Cutibacterium acnes and Staphylococcus epidermidis

Acne vulgaris is a prevalent skin condition that is caused by an imbalance in skin microbiomes mainly by the overgrowth of strains such as Cutibacterium acnes and Staphylococcus epidermidis which affect both teenagers and adults. Drug resistance, dosing, mood alteration, and other issues hinder traditional therapy. This study aimed to create a novel dissolvable nanofiber patch containing essential oils (EOs) from Lavandula angustifolia and Mentha piperita for acne vulgaris treatment. The EOs were characterized based on antioxidant activity and chemical composition using HPLC and GC/MS analysis. The antimicrobial activity against C. acnes and S. epidermidis was observed by the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The MICs were in the range of 5.7-9.4 μL/mL, and MBCs 9.4-25.0 μL/mL. The EOs were integrated into gelatin nanofibers by electrospinning and SEM images of the fibers were taken. Only the addition of 20% of pure essential oil led to minor diameter and morphology alteration. The agar diffusion tests were performed. Pure and diluted Eos in almond oil exhibited a strong antibacterial effect on C. acnes and S. epidermidis. After incorporation into nanofibers, we were able to focus the antimicrobial effect only on the spot of application with no effect on the surrounding microorganisms. Lastly, for cytotoxicity evaluation, and MTT assay was performed with promising results that samples in the tested range had a low impact on HaCaT cell line viability. In conclusion, our gelatin nanofibers containing EOs are suitable for further investigation as prospective antimicrobial patches for acne vulgaris local treatment.

Basic sensory properties of essential oils from aromatic plants and their applications: a critical review

With higher standards in terms of diet and leisure enjoyment, spices and essential oils of aromatic plants (APEOs) are no longer confined to the food industry. The essential oils (EOs) produced from them are the active ingredients that contribute to different flavors. The multiple odor sensory properties and their taste characteristics of APEOs are responsible for their widespread use. The research on the flavor of APEOs is an evolving process attracting the attention among scientists in the past decades. For APEOs, which are used for a long time in the catering and leisure industries, it is necessary to analyze the components associated with the aromas and the tastes. It is important to identify the volatile components and assure quality of APEOs in order to expand their application. It is worth celebrating the different means by which the loss of flavor of APEOs can be retarded in practice. Unfortunately, relatively little research has been done on the structure and flavor mechanisms of APEOs. This also points the way to future research on APEOs.Therefore, this paper reviews the principles of flavor, identification of components and sensory pathways in humans for APEOs. Moreover, the article outlines the means of increasing the efficiency of using of APEOs. Finally, with respect to the sensory applications of APEOs, the review focuses on the practical application of APEOs in food sector and in aromatherapy.

Evaluation of the Antibacterial Properties of Polyvinyl Alcohol-Pullulan Scaffolds Loaded with Nepeta racemosa Lam. Essential Oil and Perspectives for Possible Applications

Essential oil of Nepeta racemosa Lam. was extracted and characterized to determine its antimicrobial activity and potential use in applications. The essential oil was loaded on polyvinyl alcohol-pullulan films and gels and characterized by optical microscopy, scanning electron microscopy, and UV-Vis spectroscopy before having its antimicrobial capacities assessed. The essential oil extracted from Nepeta racemosa Lam. was characterized using gas chromatography coupled with mass spectroscopy, which indicated that the most abundant component was nepetalic acid (55.5%), followed by eucalyptol (10.7%) and other compounds with concentrations of about 5% or less. The essential oil, as well as the loaded films and gels, exhibited good antibacterial activity on both gram-positive and gram-negative strains, with growth inhibition zones larger in some cases than for gentamicin, indicating excellent premises for using these essential-oil-loaded materials for applications in the food industry or biomedicine.

Mathematical modeling of Escherichia coli O157:H7 growth in carrot juice influenced by Thymbra capitata essential oil, heat treatment, and storage temperature

The aim of this study was to develop a mathematical model describing the survival of Escherichia coli O157:H7 in carrot juice treated with Thymbra capitata essential oil combined with mild heat treatment and stored at different temperatures. The viable count method was used to investigate the effect of the treatment on bacterial survival, and the response surface methodology was used to develop a statistical model fitting the data. The results showed that the variance of bacterial growth is explained by storage temperature (37 %) and heat treatment (35 %), these are followed by Thymbra capitata essential oil (18 %) and their interaction (9 %). Positive multiplicative interaction was obtained for any pair of the studied treatments and cooperative effect synergy was observed over a large domain of these factors. A mathematical model was successfully developed to describe Escherichia coli O157:H7 response to the selected factors, within the study limits, and to estimate the risk of juice contamination and shelf-life. Based on our results, the use of Thymbra capitata essential oil combined with heat treatment may control Escherichia coli O157:H7 growth in carrot juice stored at low temperature.

Application of natamycin and farnesol as bioprotection agents to inhibit biofilm formation of yeasts and foodborne bacterial pathogens in apple juice processing lines

Biofilms serve as a reservoir for pathogenic and spoilage microorganisms, and their removal from different surfaces is a recurring problem in the beverage industry. This study aimed to investigate the effect of a combination of natamycin (NAT, 0.01 mmol/l) and farnesol (FAR, 0.6 mmol/l) against biofilms on ultrafiltration (UF) membranes and stainless steel (SS) surfaces using apple juice as food matrix. The co-adhesion of Rhodotorula mucilaginosa, Candida tropicalis, C. krusei and C. kefyr (mixed-yeast) with Listeria monocytogenes, Salmonella enterica or Escherichia coli O157:H7 (multi-species) in presence of NAT + FAR was evaluated for 2, 24, 48 h. In biofilms treated with NAT + FAR were observed by cell quantification and microscopy, inhibition of the filamentous yeast forms, disruption of the tri-dimensional structure and a high detachment of yeast cells. NAT + FAR affected the biofilms independently of the surfaces used and the presence (or not) of bacteria. L. monocytogenes was the most susceptible (p < 0.001) in multi-species biofilms, followed by E. coli O157:H7 on both surfaces (p < 0.001), whereas the growth of S. enterica was reduced (p < 0.05) in SS but not in UF-membranes (p > 0.05). Since the combination NAT + FAR affected the structure and viability of yeast species and foodborne pathogens in multi-species biofilms developed on UF-membranes and SS surfaces, the combination proposed could be considered a promising control agent to prevent biofilms in apple juice processing lines.