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Aim: Hexanal and geraniol are essential oil components with anti‐quorum sensing (QS) activity against Pseudomonas fluorescens. This study demonstrated that QS inhibition (QSI) efficacy of the hexanal and geraniol combination (HG) was significantly higher when compared to those of their mono‐counterparts at the same concentration. Methods and Results: Tests on P. fluorescens motility, biofilm formation, acyl‐homoserine lactones' (AHLs) production, gene expression in vitro, and molecular docking in silico were conducted to evaluate the synergistic effect of hexanal and geraniol on QSI. HG mixture at 0.5 minimal inhibitory concentration (MIC) showed a strong synergistic inhibition of biofilm formation (51.8%), motility (60.13%), and extracellular protease activity (58.9%) of P. fluorescens. The synthesis of AHLs, e.g., C8‐HSL and C12‐HSL, was inhibited by hexanal, geraniol, and HG; both AHLs are responsible for regulating virulence factors in P. fluorescens. The expression of pcoI and gacA genes regulating AHL synthetase and sensor kinase was significantly down‐regulated by HG (0.29 and 0.38‐fold) at 0.5 MIC. Hexanal and HG showed significant inhibition of the expression of pcoR and gacS genes, which are responsible for AHL receptor protein and response regulation; however, geraniol failed to downregulate the two genes. Molecular docking in silico also supported these findings. Hexanal, which gets inserted into the minor groove of pcoI/pcoR DNA fragments, inhibits the expression of both the genes. Both hexanal (−31.487 kcal/mol) and geraniol (−25.716 kcal/mol) had a higher binding affinity with PcoI protein than the halogenated furanone C30 (−24.829 kcal/mol), which is a known competitor of AHLs. Similarly, hexanal and geraniol strongly bind to the PcoR protein also. Conclusions: It was found that HG at 0.5 MIC could effectively inhibit QS by suppressing the expression of pcoR/gacS and gacA/gacS genes and therefore, could inhibit the motility and biofilm formation of P. fluorescens. Significance and Impact of the Study: The present study indicated that HG at sub‐MIC as QS inhibitor could be further developed as a new preservative of agri‐food products. [ABSTRACT FROM AUTHOR]

Neutral cellulase-assisted steam distillation (NCSD) was developed to extract essential oil from Valeriana officinalis L. root, and a single-factor experiment was designed to optimize the NCSD. Chemical composition was subsequently compared between Valeriana officinalis L. root essential oil (VORO) extracted by NCSD and conventional steam distillation (SD). Results show that the highest yield of VORO extracted by NCSD was 68.09% higher than that extracted by SD. Results of antibacterial activity indicate that the two VOROs had an equally strong antibacterial activity of Bacillus subtilis, Staphylococcus aureus, and Escherichia coli with minimum inhibitory concentration (MIC) of 0.88, 1.75, and 3.50 mg/mL, respectively. Both VOROs also showed sufficiently high antioxidant and anti-dust mite abilities. The VORO concentration higher than 0.35 mg/mL was regarded as an A-grade dust mite repellent and B-grade miticide. This study has emphasized the significances of VORO in the food and textile industries as a potential additive. [ABSTRACT FROM AUTHOR]

The problem of drug resistance of food borne pathogens is becoming more and more serious. Although traditional antimicrobial agents have good therapeutic effects on a variety of food borne pathogens, more effective antimicrobial agents are still needed to combat the development of drug-resistant food borne pathogens. Plant-based natural essential oils (EOs) are widely used because of their remarkable antimicrobial activity. A potential strategy to address food borne pathogens drug resistance is to use a combination of EOs and antimicrobial agents. Because EOs have multi-target inhibitory effects on microorganisms, combining them with drugs can enhance the activity of the drugs and avoid the emergence of food borne pathogens drug resistance. This paper introduces the main factors affecting the antibacterial activity of EOs and describes methods for evaluating their synergistic antibacterial effects. The possible mechanisms of action of EOs and the synergistic inhibitory effects on pathogens of EOs in combination with antimicrobial agents is described. In summary, the combined use of EOs and existing antimicrobial agents is a promising potential new antibacterial therapy. [ABSTRACT FROM AUTHOR]

Hexanal is an essential oil component which has quorum sensing (QS) inhibitor effect on vegetable spoilage bacteria such as Erwinia carotovora (E. carotovora) and Pseudomonas fluorescens (P. fluorescens). However, the QS inhibitory (QSI) effect of hexanal on Autoinducer‐2 (AI‐2), biofilm formation, and enzyme activity is not well understood. Our results showed that the contents of AI‐2 produced by E. carotovora were higher than P. fluorescens, and the 4,5‐Dihydroxy‐2,3‐pentanedione (DPD) concentrations were significantly (p <.05) inhibited by hexanal. Adding DPD exogenously could form more biofilm when inhibited by 1/2 of minimum inhibitory concentration (MIC) of hexanal, which showed that QSI effect of hexanal on biofilm was due to its inhibition on AI‐2. There was no significant increase in enzyme activity, which suggested that enzyme inhibition by hexanal may not due to AI‐2. Understanding the relationship between QSI effect of hexanal on AI‐2, biofilm formation, and enzyme activity can improve to suppress decomposition of vegetables after harvest. Practical applications: Hexanal is an EO component which has shown good QSI effect on biofilm formation and exoenzyme activities of P. fluorescens and E. carotovora. However, the reason for the QSI effect of hexanal was still unclear. In this study, hexanal as a QS inhibitor on these two vegetable spoilage bacteria was studied from the perspective of AI‐2 signal molecule. Understanding the QS inhibition of hexanal on AI‐2 signal molecule of spoilage bacteria and its relationship with biofilm formation and enzyme activity was necessary for the application of more EO components as QS inhibitor to suppress corruption of vegetables after harvest. [ABSTRACT FROM AUTHOR]

Biofilm formation is mainly controlled by quorum sensing (QS). To prevent biofilm formation on stainless steel, the QS inhibitory (QSI) effect of 10 essential oil (EO) components on dual‐species bacterial biofilm (Erwinia carotovora and Pseudomonas fluorescens) were screened. Geraniol showed the best QSI effect on dual‐species biofilm with an inhibition rate of 61.27%. Meanwhile, geraniol at the sub‐MIC significantly restrained the swimming, swarming, twitching motilities, exopolysaccharide production, and biofilm biomass of the two bacterial biofilms. The reduction of QS regulatory factors was possibly attributed to the inhibition of AI‐2 signal molecule and thereby controlled the formation of biofilm. The viable cells in the dual‐species biofilm formed on stainless steel were also decreased by using geraniol at sub‐MICs. Such an inhibition also showed a good dose‐dependence. Results of this study indicated that geraniol can be utilized as a QSI to achieve biofilm control on foods. Practical applications: EOs can be utilized as a group of natural food preservers. However, high value and significant flavoring impact restrict their applications in the food industry. Facing these issues, taken Eos as QSI would be helpful to achieve microbial control at a low concentration level. Geraniol is an important component in many essential oils. In this study, the QSI effect of geraniol on the AI‐2 signal molecule production, and biofilm formation in Erwinia carotovora and Pseudomonas fluorescens were elucidated. These findings would support that geraniol can be further developed as a promising strategy to achieve postharvest preservation of vegetables. [ABSTRACT FROM AUTHOR]

Consumers' pursuit to a healthy lifestyle has promoted people to develop new technologies that can prolong the shelf life of food without the use of preservatives. Compared with other types of preservation, edible microcapsules containing essential oils (EOs) are becoming more and more popular especially the starch microcapsules containing essential oil (EOs-starch microcapsules) because of their environmentally friendly, healthier characteristics and the ability to carry active ingredients. In addition, the EOs-starch microcapsules can also reduce the flavor influence and prolong the action time of essential oil on food through its slow release effect, which can promote the use of EOs in food. Understanding the different collocation of edible starch microcapsules and EOs and the related antibacterial mechanism will be more effective and targeted to promote the application of EOs in the real food system. The review focus on the contribution of EOs-starch microcapsules to prolong the shelf life of food products, (1) binding characteristics of EOs-starch microcapsules were analyzed, (2) systematically summarizing the main materials and methods for preparing the EOs-microcapsules, (3) specifically addressing the action mechanisms of EOs-starch microcapsules on microorganism, (4) discussing the applications of EOs-starch microcapsules in specific food. [ABSTRACT FROM AUTHOR]

In recent years, with the continuous improvement of people's living standard, the importance of healthy lifestyles is becoming more and more recognized. Therefore, food safety has attracted much attention. This has prompted people to study new technologies that can guarantee food safety without the use of preservatives. Compared with other types of food preservatives, essential oils (EOs) are gotten more attention, because they meet the current development trend of food additives about "green", "safety" and "health". Therefore, this paper focuses on the research of effective contribution of EOs to inhibit the growth of foodborne pathogens, systematically summarized the commonly used EOs and their main extraction methods and chemical components and, the antibacterial mechanism of EOs on food borne pathogens, systematically analysis the specific application case of EOs in food discussed. Hoping to provide some reference and help to the relevant researchers. [ABSTRACT FROM AUTHOR]

Compared with other types of packaging, edible coatings are becoming more and more popular because of their more environmentally friendly properties and active ingredients carrying ability. The edible coating can reduce the influence of essential oils (EOs) on the flavor of the product and also can prolong the action time of EOs through the slow-release effect, which effectively promote the application of EOs in food. Understanding the different combinations of edible coatings and EOs as well as their antimicrobial effects on different microorganisms will be more powerful and targeted to promote the application of EOs in real food systems. The review focus on the contribution of the combination of EOs and edible coatings (EO-edible coatings) to prolong the shelf life of food products, (1) specifically addressing the main materials used in the preparation of EO-edible coatings and the application of EO-edible coatings in the product, (2) systematically summarizing the main production method of EO-edible coatings, (3) discussing the antiseptic activity of EO-edible coatings on different microorganisms in food. [ABSTRACT FROM AUTHOR]

Traditional packaging has reached its limits in ensuring food quality and prolonging shelf life. In this study, we developed antifungal sachets containing essential oils (EOs) in microcapsules (ASEOs-CM) and evaluated their application potential in bread preservation. The results showed that the release of EOs from ASEOs-CM at 25 °C followed first-order kinetics. In addition, EOs-containing ASEOs-CM had strong inhibitory effects on microorganisms in vitro and effectively inhibited the growth of molds and yeasts on sliced bread. In the experimental group, the contents of eugenol and citral EOs on bread increased during storage. Breads in three different packages (LDPE, PP and HDPE) had a total shelf life of 13, 13, and 15 d, respectively, while control breads had a shelf life of 5 d. Sachets did not affect the sensory properties of bread. Therefore, the use of ASEOs-CM was an effective, safe, and sustainable preservation method for breads. • The sachets of compound essential oil containing microcapsules were developed. • The sachets has good antifungal activity. • The sachets has no effect on the sensory characteristics of bread. • The sachets can be used to extend the shelf life of baked products. [ABSTRACT FROM AUTHOR]

• The combination of eugenol and citral (S EC) can inhibit energy metabolism of Penicillium roqueforti. • The S EC can damage the cell membrane of mycelia. • The S EC affect the composition of cell membrane fatty acids. • The S EC can inhibit the expression of succinate dehydrogenase, isocitrate dehydrogenase and fumarate hydratase related genes. Agriculture products spoilage caused by mold not only causes huge economic losses, but also poses a safety hazard to human health. Although essential oils (EOs) are widely used for agriculture products antisepsis, little is known about the synergistic antifungal mechanisms of their major components. In this paper, the synergistic mechanism of eugenol and citral (S EC) on Penicillium roqueforti was studied. The results showed that S EC caused irreversible damage to the cell membrane of P. roqueforti , resulting in significant changes in membrane protein conformation and fatty acid content, among which citral had a greater effect on fatty acid content than eugenol. Through the analysis of mitochondrial morphology and membrane potential, it was found that S EC treatment resulted in serious collapse of mitochondria and significant increase of membrane potential. In this process, the contribution rate of eugenol was higher than that of citral. Further analysis of the tricarboxylic acid cycle (TCA) pathway showed that S EC could inhibit the activity of key enzymes and the production of energy charge in the TCA pathway, resulting in significant down-regulation of gene expression of three key molecules (succinate dehydrogenase, isocitrate dehydrogenase and fumarate hydratase). In conclusion, these results indicated that S EC could kill P. roqueforti through the tricarboxylic acid cycle. [ABSTRACT FROM AUTHOR]

The synergistic effects of different essential oils can not only reduce their dosage and cost, but also improve their biological activity. The aim of this study was to evaluate the synergistic antifungal effect of eugenol and citral (S EC) on Penicillium roqueforti. Determination of reactive oxygen species (ROS) and malondialdehyde content indicated that S EC could induce membrane lipid peroxidation, and the contribution of citral was greater than that of eugenol. In addition, downregulation of the gene encoding an NADPH oxidase subunit indicated that the ROS burst induced by S EC was mediated by NADPH oxidase. Scanning electron microscope (SEM) and transmission electron microscope (TEM), propidium iodide treatment, DNA gel electrophoresis and cell leakage experiments showed that S EC destroyed the integrity of the cell membrane and internal structures, and degraded the cell contents, and the contribution of eugenol was greater than that of citral. These results showed that S EC inhibited the activity of P. roqueforti more effectively than eugenol or citral alone, by inducing membrane lipid peroxidation and promoting the ability of eugenol to destroy the cell membrane. The combined agents eventually caused leakage of the cell contents, and ultimately cell death. •The combination of eugenol and citral (S EC) had synergistic inhibition effect against P. roqueforti. •S EC treatment could significantly induce lipid peroxidation. •S EC treatment resulted in damaged the morphology of cells. •S EC treatment resulted in loss of plasma membrane integrity. [ABSTRACT FROM AUTHOR]

In this work, corn porous starch was used as a food grade polymer to microencapsulate essential oil (EO), the effects of temperature on adsorption of EO were investigated, and adsorption kinetics curves were plotted. Using this approach, the sustained‐release antibacterial effects of porous starch microcapsules containing EOs (PSM‐EOs) against Penicillium roqueforti and Aspergillus niger were explored under accelerated volatilization under high temperature conditions, and microencapsulation was successfully applied to bread preservation. The results showed that temperature had a significant effect on the adsorption capacity, and adsorption rate was controlled by both liquid film diffusion and intraparticle diffusion. The activation energy (Ea) of the adsorption process was 7.96 K J/mol as calculated using the Arrhenius equation. The results of antibacterial experiments showed that PSM‐EOs exhibited superior sustained‐release antibacterial effects and significantly prolonged the shelf life of bread, compared with controls. Practical applications: The spoilage caused by mold contamination is a serious challenge for the bread industry. At present, the main preservative used in baking products is calcium propionate, a chemical preservative. However, calcium propionate can be decomposed to produce propionic acid under the action of intestinal microorganisms. Propionic acid is an important factor in inducing diabetes mellitus. Therefore, it is necessary to explore new preservation techniques rather than bread with calcium propionate. In this paper, porous starch microcapsules containing essential oil were prepared, and the adsorption kinetics curve of porous starch to essential oil was plotted. On this basis, the inhibition effect of porous starch microcapsules containing essential oil in high temperature accelerated volatilization on the main mold (P. roqueforti and A. niger) causing bread corruption was investigated. The aim is to provide new ideas for bread preservation. [ABSTRACT FROM AUTHOR]

Aromatic essential oils (EO) are important plant extracts that have attracted great interest for their various biological activities and their potential to replace chemical preservatives in the field of food preservation. Moreover, the volatility of EOs has further expanded their applications in antibacterial packaging (AP) systems. This review focuses on the contributions of EOs to food packaging by (1) introducing the antibacterial activity of EOs; (2) summarizing the implementation of EO-APs; (3) analyzing the applications of EO-APs in food preservation; and (4) assessing the safety of EOs. Understanding the different combinations of EOs and food packaging will help improve the effectiveness of EO-APs in food preservation and better target their use, which will promote their application in food systems. By combining them with packaging materials, the adverse flavor of EOs can be reduced and their action time prolonged, which will greatly improve their effective utilization rate in food preservation. • Essential oils can be used as ingredients of active food packaging. • Introduced the main active ingredients and antibacterial effects of EOs commonly used in food preservation. • Focused on summarizing the implementation of EOs-AP. • Analyzed the application of EOs-AP in food preservation. [ABSTRACT FROM AUTHOR]

This study evaluated the minimum inhibition concentration (MIC) and minimum lethal concentration (MLC) of cinnamon and clove essential oils against mold growth on green bean cake and finger citron crisp cake, and also examined the effects of these two essential oils and their application methods on the shelf life of the baked products in normal and vacuum packages by accelerated storage test. The results showed that the MIC of cinnamon and clove essential oils against molds were 0.21–0.83 and 0.21–1.67 μL/mL, respectively and the MLC were 0.42–0.83 and 0.83–1.67 μL/mL, respectively. In normal package cinnamon and clove essential oils could prolong the shelf life of green bean cake 9–10 and 3–4 days, respectively and could prolong the shelf life of finger citron crisp cake 5–6 and 2–3 days, respectively. And in vacuum package they were 15–16, 8–9, 10–12 and 7–9 days, respectively in turn. [ABSTRACT FROM AUTHOR]

Borneol was widely used in traditional Chinese medicine formulas due to its pharmacological activities, e.g. sedative, anti-inflammatory, and anti-ischemic properties. Cinnamomum camphora (L.) J.Presl essential oil (BEO) is a by-product of natural crystalline borneol (NCB) production obtained by steam distillation of Cinnamomum camphora (L.) J.Presl leaves, and borneol was the main component of BEO. This study aims to investigate the anti-inflammatory effect of BEO and its corresponding mechanisms through in vitro and in vivo studies. Human erythrocyte membrane stability assay and the acute inflammation murine model (xylene-induced ear edema) were chosen to evaluate the anti-inflammatory effect of BEO. Expression of inflammatory mediators, including interleukin (IL)-1β, IL-6, and tumor necrosis factor α (TNF-α) was determined by real-time quantitative polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assays (ELISA). The functional compounds in the BEO were identified by using gas chromatography-mass spectrometry (GC-MS). The steady-state transdermal diffusion rates of BEO and BEO nano-emulsion with were also determined in this study. Cytotoxicity of BEO was analyzed by cell counting kit-8 (CCK-8) assay. The BEO showed a high human erythrocyte membrane stabilization by inhibiting heat-induced hemolysis (IC 50 = 5.29 mg/mL) and hypotonic solution-induced hemolysis (IC 50 = 0.26 mg/mL) in vitro. The BEO was topically applied to mice auricles, both single and repeated administration significantly reduced xylene-induced auricle swelling (p < 0.0001). Expression of inflammatory mediators, including interleukin (IL)-1β, IL-6, and tumor necrosis factor α (TNF-α) in serum and tissue was significantly downregulated (p < 0.05), so as to the mRNA expression of IL-1β (p ＜0.05) and TNF-α (p < 0.001). A total of 43 components were identified and quantified by GC-MS. The most abundant was borneol [178.3 mg/mL, 20.9% (m/v)], followed by β-caryophyllene (116.3 mg/mL), camphor (115.2 mg/mL), and limonene (89.4 mg/mL). For determining the skin permeability of BEO, the steady-state transdermal diffusion rates of BEO and BEO nano-emulsion were determined to be 6.7 and 8.9 mg/cm2·h, respectively. It is suspected that the anti-inflammatory effects in vivo and in vitro were derived from the above-mentioned components in the BEO. These findings will facilitate the development of BEO as a new and natural therapeutic agent for inflammatory skin conditions. Image 1 • Cinnamomum camphora (L.) J.Presl essential oil (BEO) composition was analyzed. • Anti-inflammatory potential of BEO was evaluated in vivo and in vitro. • BEO cytotoxicity was assessed in human keratinocytes HaCaT cells. • Transdermal permeation rate of BEO showed the good skin permeability. [ABSTRACT FROM AUTHOR]

[Display omitted] • Encapsulated LEO was successfully produced by ionic gelation process. • Chitosan films with LEO microspheres and cranberry juice were developed. • The effect of LEO microspheres and cranberry juice in the films were investigated. • LEO microspheres and cranberry juice improved some of the chitosan film qualities. • Chitosan films with LEO microspheres and cranberry juice showed antimicrobial activity. Research about biodegradable antimicrobial films continues to receive a lot of attention due to the plastic pollution crisis and the need for environment-friendly and safe food products. In this study, we developed chitosan-based antimicrobial films using a combination of encapsulated lemon essential oil (LEO) by ionic gelation and cranberry juice and evaluated the performance of the films. Our results indicated that the incorporation of LEO microspheres and cranberry juice into the chitosan films improved the UV barrier and thermal properties as well as antioxidant activity of the films. The increase in antioxidants was consistent with the chemical components in LEO and cranberry juice as determined by GC–MS; some of which possess antioxidant properties. Furthermore, following antimicrobial activity test, considerable inhibition halo of 11 and 20 mm were observed respectively against fungi Candida albicans and Penicillium roqueforti , particularly in presence of the film containing both LEO microspheres and cranberry juice. [ABSTRACT FROM AUTHOR]

• Cinnamomum camphora chvar. Borneol essential oil (BEO) was obtained. • Neutral cellulase assisted steam distillation (NCSD) enhanced yield of BEO. • Working parameters of NCSD were optimized through response surface methodology. • 62 volatile compounds in total were identified in BEO. • Majority of chemical constituents in BEO using NCSD remain unchanged. Cinnamomum camphora chvar. Borneol essential oil (BEO) has potential biological activity and has attracted considerable interest. In this study, neutral cellulase assisted-steam distillation (NCSD) was first developed to extract BEO, followed by optimizing NCSD through single-factor test (SFT) and response surface methodology (RSM). The processing conditions of NCSD were optimized as follows: addition of neutral cellulase (0.36 FPU/g of fresh leaves), duration of enzymolysis (5.39 h), temperature (51.47 °C), and pH (6.15). The predicted yield of BEO using NCSD was 1.03% within 95% confidence intervals of the actual yield of BEO (1.03 ± 0.03%), which was 58% higher than the yield of BEO using conventional steam distillation (SD) without neutral cellulase pre-treatment (0.65 ± 0.04%). Moreover, chemical constituents of BEO using NCSD and SD were evaluated and compared. Results show that 62 volatile compounds were identified, and majority of functional compounds in the BEO using NCSD and SD were detected simultaneously, e.g. borneol, β-pinene, and β-cadinene. A significantly higher proportion of compounds with relatively lower molecular weight (MW) ranging from 130 to 150 and higher MW ranging from 205 to 225 were detected in the BEO using NCSD, which may contribute to a stronger flavoring impact and influence the overall flavor profile of the BEO. Therefore, significance of this study is to develop the NCSD as a more effective method than the SD for extracting the BEO from Cinnamomum camphora chvar. Borneol fresh leaves without compromising its quality and remaining the majority of chemical consitutents unchanged. [ABSTRACT FROM AUTHOR]