Nanoemulsified D-Limonene Reduces the Heat Resistance of Salmonella Senftenberg over 50 Times (original) (raw)
Related papers
Scientific Reports, 2020
Consumers’ demands for ready-to-eat, fresh-like products are on the rise during the last years. This type of products have minimal processing conditions that can enable the survival and replication of pathogenic microorganisms. Among them, Listeria monocytogenes is of special concern, due to its relatively high mortality rate and its ability to replicate under refrigeration conditions. Previous research works have shown that nanoemulsified essential oils in combination with thermal treatments are effective for inactivating L. monocytogenes. However, previous research works were limited to isothermal conditions, whereas actual processing conditions in industry are dynamic. Under dynamic conditions, microorganism can respond unexpectedly to the thermal stress (e.g. adaptation, acclimation or increased sensitivity). In this work, we assess the combination of nanoemulsified D-limonene with thermal treatments under isothermal and dynamic conditions. The nanoemulsion was prepared following an innovative methodology using soya lecithin, a natural compound as well as the essential oil. Under isothermal heating conditions, the addition of the antimicrobial enables a reduction of the treatment time by a factor of 25. For time-varying treatments, dynamic effects were relevant. Treatments with a high heating rate (20 °C/min) are more effective than those with a slow heating rate (1 °C/min). This investigation demonstrates that the addition of nanoemulsified D-limonene can greatly reduce the intensity of the thermal treatments currently applied in the food industry. Hence, it can improve the product quality without impacting its safety.
Food Microbiology, 2017
The application of D-limonene in form of nanoemulsion has been proved to reduce dramatically the thermal resistance of Listeria monocytogenes in culture media. The present research shows very promising results on the application in food products. The thermal resistance of L. monocytogenes was reduced 90 times when 0.5 mM nanoemulsified D-limonene was added to apple juice. This is the biggest reduction in the heat resistance of a microorganism caused by an antimicrobial described ever. However, no effect was found in carrot juice. A carrot juice system was prepared in an attempt to unravel which juice constituents were responsible for the lack of effect. When fat and fibre were not included in the carrot juice system formulation, the thermal resistance of L. monocytogenes was, again, dramatically reduced in presence of nanoemulsified D-limonene, so these components were shown to interfere with the effect. Once this interaction with food constituents becomes solved, the addition of nanoemulsified antimicrobials would allow to reduce greatly the intensity of the thermal treatments currently applied in the food processing industry.
2020
Consumers’ demands for ready-to-eat, fresh-like products are on the rise during the last years. This type of products have minimal processing conditions that can enable the survival and replication of pathogenic microorganisms. Among them, Listeria monocytogenes is of special concern, due to its relatively high mortality rate and its ability to replicate under refrigeration conditions. Previous research works have shown that nanoemulsified essential oils in combination with thermal treatments are effective for inactivating L. monocytogenes. However, previous research works were limited to isothermal conditions, whereas actual processing conditions in industry are dynamic. Under dynamic conditions, microorganism can respond unexpectedly to the thermal stress (e.g. adaptation, acclimation or increased sensitivity). In this work, we assess the combination of nanoemulsified D-limonene with thermal treatments under isothermal and dynamic conditions. The nanoemulsion was prepared followin...
Journal of Cluster Science, 2019
In the present study, EOs of commonly used spices i.e. coriander, cumin, fennel, lemongrass and pepper and their major components (linalool, cuminaldehyde, anethole, citral and beta-caryophyllene) were nanoemulsified and investigated for their antibacterial and anti-biofilm activities against Salmonella enterica Typhimurium. The mean droplet size of the nanoemulsion ranged from 16.99 to 165.20 nm for EOs and 22.40 to 223.90 nm for their major compounds. Nanoemulsion of all EOs and their compounds (cuminaldehyde, anethol and citral) were stable for 30 days while phase separation was noticed in linalool and beta-caryophyllene after 5 and 10 days of storage, respectively. Among the investigated samples, citral nanoemulsion showed the highest antibacterial (MIC 0.156%) and anti-biofilm activity (79.9%) and was therefore selected for its application in fresh cut pineapple model. Treatment with citral nanoemulsion on the cut pineapple surface led to 2.57 log CFU/g reduction of the S. enterica Typhimurium population. Scanning electron microscopy revealed reduction of biofilms on the cut pineapple surface upon citral nanoemulsion treatment. Hence, we envisage that citral nanoemulsion can be further explored as natural antibacterial and anti-biofilm agent for food preservation applications.
Tropical Animal Science Journal, 2021
This work was designed to monitor and track Salmonella spp. in the different internal organs (heart, liver, spleen, and caecum) of 247 bird species (chickens n=176, chicks n=47, ducks n=15, and ducklings n=9) with variable ages in two governorates; El-Fayoum and Beni-Suef, Egypt. Besides assessing the antimicrobial activity of antibacterial agents, essential oils, oils nano-emulsion, and their interactions with each other against salmonellae isolates for their control at the farm level. All samples were collected aseptically for further microbiological and serological investigations. Moreover, the efficiency of essential oils and oils nano-emulsion (thymol, carvacrol, basil, and cinnamon) against recovered Salmonellae were tested using the agar dilution method. A total of fourteen Salmonella serotypes were detected from different investigated internal organs (heart, liver, and spleen), and the three most predominant serovars were S. virchow (17.14%), S. infantis (11.43%), and S. anatum (11.43%). The resistance profile of Salmonella spp. referred to 47.14%, 40.0%, 31.43%, 25.71%, 21.43%, 21.43%, and 21.43% against ampicillin, chloramphenicol, gentamicin, aztreonam, cefazolin, cefotaxime, and tobramycin, respectively. The ability of essential oils (carvacrol oil 0.01%, basil 0.1%, cinnamon 0.01%, and thymol oil 0.01%) to inhibit the growth of Salmonellae differed significantly at 34.29%, 17.14%, 11.43%, and 1.43%, respectively (p<0.05). Oppositely, essential oils nano-emulsion (thymol 0.01%, carvacrol 0.001%, basil 0.1%, and cinnamon 0.01%) showed no inhibitory effect on the growth of Salmonella species. In conclusion, the interactive action between essential oils and antimicrobial agents approved the ability to enhance the susceptibility of the resistant Salmonella isolates against gentamicin, tobramycin, chloramphenicol, and cefazolin. In addition, the interactive action between essential oils nano-emulsion and antimicrobial agents on resistant Salmonella isolates revealed a complete enhanced effect against cefotaxime and variable enhancement against aztreonam.
Essential Oil Nanoemulsions and their Antimicrobial and Food Applications
Current Research in Nutrition and Food Science Journal
The consumer awareness for secure insignificantly handled food has constrained the food dealers either to decrease the measure of chemically synthetic antimicrobial substances or to replace them with natural ones. Essential oils (EO) extracted from edible, therapeutic and herbal plants have been well recognized as natural antimicrobial additives. As characteristic then viable antimicrobials, EO have been progressively observed towards control of foodborne microbes and progression of nourishment wellbeing. It is ordinarily hard to achieve high antimicrobial vulnerability when mixing with EO in nourishment based items because of low dissolvability of water and interactive binding. Subsequently, the delivery system of nanoemulsion-based EO is emerging as aviable solution to control the growth of foodborne pathogens. Lipophilic compounds are distributed uniformly in the aqueous phase with the help of nanoemulsion technique. Therefore, the nanoemulsion formulation is generally comprised ...
Journal of Food Science and Technology, 2019
Nanoemulsions exhibit a number of advantages to carry and deliver lipophilic compounds such as essential oils (EOs) due to their good stability and high surface area per volume unit. The purpose of this work was to assess the long-term stability of nanoemulsions of clove and lemongrass (LG) EOs and their principal components eugenol and citral (CI), respectively, at 3 different concentrations (2, 5 or 10 times their respective minimum inhibitory concentrations) and at two storage temperatures (1°C and 21°C). The initial droplet size of LG and CI-loaded nanoemulsions was below 100 nm and most of them kept droplet sizes in the nano-range until the end of storage at both temperatures. The f-potential was lower than-40 mV, but it increased through storage, indicating a weaker alginate adsorption at the oil surface at both temperatures. The antimicrobial activity increased with the EOs concentration and was negatively affected by the highest storage temperature. Nanoemulsions containing CI and LG were able to significantly decrease Escherichia coli counts during storage, particularly at 1°C. Nanoemulsions containing 1.0 and 2.0% w/w CI and 2.5% w/w LG were the most efficient in reducing Botrytis cinerea growth through storage, mainly at 1°C. The nanoemulsions containing 1.0 and 2.0% w/w CI, as well as, 1.25 and 2.5% w/w LG better maintained their stability and antimicrobial effect along 6-months storage mainly when at 1°C, making those nanoemulsions suitable as edible coatings for food preservation. Future studies should be oriented to evaluate the impact of these nanoemulsions on the organoleptic properties of coated foods and their potential toxicity.
Plos One, 2013
This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits&amp;amp;amp;amp;amp;#39; essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments.
Nanomaterials
Mini-emulsion polymerization was applied for the synthesis of cross-linked polymeric nanoparticles comprised of methyl methacrylate (MMA) and Triethylene Glycol Dimethacrylate (TEGDMA) copolymers, used as matrix-carriers for hosting D-limonene. D-limonene was selected as a model essential oil, well known for its pleasant odor and its enhanced antimicrobial properties. The synthesized particles were assessed for their morphology and geometric characteristics by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM), which revealed the formation of particles with mean diameters at the nanoscale (D[3,2] = 0.135 μm), with a spherical shape, while the dried particles formed larger clusters of several microns (D[3,2] = 80.69 μm). The percentage of the loaded D-limonene was quantified by Thermogravimetric Analysis (TGA), complemented by Gas Chromatography-Mass Spectrometry analysis coupled with a pyrolysis unit (Py/GC-MS). The results showed that the volatiles emitted by the...