•The addition of citric acid to alginate and erythrosine increased elongation, thickness, tensile strength, film stiffness and water vapor permeability of films.•Alginate, acid citric, erytrosine ...(phtosensitizer) coating and FTD, effectively reduced the population of Escherichia coli.•Until the seventh day of storage the treatment with alginate, acid citric, erytrosine (phtosensitizer) coating and FTD was more effective in controlling of the population of Escherichia coli.•FTD did not cause lipid oxidation in cheese samples.
The use of edible coating is an option to improve food quality and increase product shelf life. Photodynamic therapy and acid addition may be another option which decreases the number of viable microorganism cells, including Gram-negative bacteria. The present work aimed to evaluate the application of edible coatings that have the ability to inhibit the growth of Escherichia coli, using acidic pH and photodynamic therapy, in order to increase shelf life of fresh cheese. Coatings were prepared with the addition of lactic, malic and citric acids. The control coating micrograph showed surface stains, and crystal formation was apparently accentuated by the presence of citric and malic acid, not observed in the control coating or lactic acid coating. The surface micrograph of the lactic acid alginate coating showed greater homogeneity without stains and cracks. The addition of citric acid to the coating was the best result for in vitro bacterial survival tests and was therefore chosen, this coating decreased microbiological counts in the first 7 days with smaller weight loss, controlled acidity and pH and lipid oxidation remained as expected.
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Essential oils (EOs) have strong antibacterial properties and can be potential sanitizers to reduce pathogen load and prevent cross-contamination during postharvest washing. The objective of this ...study was to investigate the efficacy of emulsions containing oregano (OR;
) and winter savory (WS;
) EOs at different concentrations (0.94 and 1.88 µL/mL) and storage times (0 h, 24 h, and 7 days), in reducing
O157:H7 on the surface of three types of lettuce (romaine, crisphead, and butterhead). The EO emulsions were compared with one no-rinse treatment and three rinse treatments using water, 200 ppm chlorine, and 80 ppm peroxyacetic acid (PAA), respectively, in a simulated washing system. The results showed that while the EO emulsions significantly reduced
O157:H7 on crisphead lettuce over time, not all treatments were effective for romaine and butterhead lettuce. The mixture of OR and WS at concentrations of 0.94 and 1.88 µL/mL was found to be the most effective in reducing
O157:H7 on inoculated lettuce, resulting in reductions of 3.52 and 3.41 log CFU/g, respectively. Furthermore, the PAA and the mixture of OR and WS at 1.88 µL/mL effectively limited bacterial cross-contamination close to the detection limit for all lettuce types during all storage times. These results suggest that OR and WS EOs could serve as potential alternatives to chemical sanitizers for postharvest lettuce washing.
This study evaluated the rose bengal‐ and erythrosine‐mediated photoinactivation against Salmonella Typhimurium and Staphylococcus aureus planktonic and sessile cells using green LED as a light ...source. The free‐living or 2‐day‐old biofilm cells were treated with different concentrations of the photosensitizing agents and subjected to irradiation. Only 5 min photosensitization with rose bengal at 25 nmol L−1 and 75 μmol L−1 completely eliminated S. aureus and S. Typhimurium planktonic cells, respectively. Erythrosine at 500 nmol L−1 and 5 min of light exposure also reduced S. aureus planktonic cells to undetectable levels. Eradication of S. aureus biofilms was achieved when 500 μmol L−1 of erythrosine or 250 μmol L−1 of rose bengal was combined with 30 min of irradiation. Scanning electron microscopy allowed the observation of morphological changes in planktonic cells and disruption of the biofilm architecture after photodynamic treatment. The overall data demonstrate that rose bengal and erythrosine activated by green LED may be a targeted strategy for controlling foodborne pathogens in both planktonic and sessile states.
Survival of S. aureus (A) biofilm and (B) planktonic cells photoinactivated with rose bengal.
ABSTRACT
In order, understanding the antimicrobial action of photodynamic therapy and how this technique can contribute to its application in the control of pathogens. The objective of the study was ...to employ a proteomic approach to investigate the protein profile of Staphylococcus aureus after antimicrobial photodynamic therapy mediated by rose bengal (RB‐aPDT). S. aureus was treated with RB (10 nmoL L−1) and illuminated with green LED (0.17 J cm−2) for cell viability evaluation. Afterward, proteomic analysis was employed for protein identification and bioinformatic tools to classify the differentially expressed proteins. The reduction in S. aureus after photoinactivation was ~2.5 log CFU mL−1. A total of 12 proteins (four up‐regulated and eight down‐regulated) correspond exclusively to alteration by RB‐aPDT. Functionally, these proteins are distributed in protein binding, structural constituent of ribosome, proton transmembrane transporter activity and ATPase activity. The effects of photodamage include alterations of levels of several proteins resulting in an activated stress response, altered membrane potential and effects on energy metabolism. These 12 proteins required the presence of both light and RB suggesting a unique response to photodynamic effects. The information about this technique contributes valuable insights into bacterial mechanisms and the mode of action of photodynamic therapy.
Antimicrobial photodynamic therapy mediated by rose bengal against Staphylococcus aureus was responsible for causing a biological change in the bacteria. The analyze these alterations were done by a proteomic approach. Initially, the samples were trypsinized and the identification was performed by liquid chromatography‐mass spectrometry. The bioinformatics tools were employed to classify the proteins due to the effects of photodamage.
•The antimicrobial effect of Piper peltatum and Piper marginatum was observed.•Synergistic interaction between Piperaceae extracts and with nisin was proven.•External morphological changes were ...observed with Piper fraction and 4-Nerolidylcatechol.•Tests in reconstituted orange juice demonstrated efficacy for use of this Piperaceae extracts.•Piperaceae were efficacy to control the Alicyclobacillus acidoterrestris in orange juice.
The present study aimed evaluate the antibacterial effect of Piper peltatum and Piper marginatum extracts against Alicyclobacillus acidoterrestris using the microdilution method. P. marginatum achieved a minimum inhibitory concentration (MIC)/minimum bactericidal concentration (MBC) of 62.50 μg/mL while P. peltatum obtained a MIC/MBC of 15.62 μg/mL, and was therefore selected for fractionation. Six fractions were obtained and tested. The hexane-dichloromethane fraction achieved the lowest MIC/MBC of 31.25 μg/mL and was fractionated, isolating the 4-Nerolidylcatechol compound (4-NC). The checkerboard method produced a synergistic effect between nisin and the crude extracts and the fraction, and an additive effect in relation to the 4-NC isolate. The application of the extracts, fraction and isolate in reconstituted orange juice previously inoculated with A. acidoterrestris proved effective as an antibacterial agent after 24 h of incubation and reduced the initial microbial population. The dose-response effect and cell viability, measured through the selectivity index, obtained values greater than 1.0, showing that the extracts were more selective for the microorganism and less toxic for the LLCM-K2 cells. Scanning electron microscopy identified changes in the membrane of the vegetative and spore cells of A. acidoterrestris when treated with this compound. The present study demonstrated the antibacterial efficacy of Piperaceae extracts and nisin against A. acidoterrestris in orange (Citrus sinensis) juice, which can therefore be considered to have major potential for application in the food industry.
Hibiscus calyx presents high content of bioactive compounds, such as anthocyanins and other phenolic compounds responsible for antioxidant activity. The present study investigated how the tea ...infusion temperature (hot and cold) can change the phytochemical profile, antimicrobial activity, and stability of hibiscus tea. The results indicated the same phytochemical profile for cold (infusion during 2 h/25 °C) and hot (7 min/75 °C) tea by using FTIR and UPLC-MS/MS analyses. Hibiscus tea, hot or cold, showed antimicrobial activity against strains of
Salmonella
Typhimurium,
Pseudomonas aeruginosa
,
Escherichia coli
and
Staphylococcus
, with minimum inhibitory concentration (MIC), obtaining values between 62.5 and 125.0 mg/ml. The hot infusion was more efficient for the bioactive compounds extraction, being 47% higher for total anthocyanins. After 48 h at 5 °C, the anthocyanin content had an average decrease of 30% (cold tea) and 48% (hot tea). Tea cream content increased to 15% (cold tea) and 37% (hot tea) after 72 h storage. Regarding the color, it was observed that after 48 h storage there was a clearing of the teas, and the L* coordinate increased from 21.03 to 24.93, and 20.72 to 24.90 for cold and hot tea, respectively. Our study indicates that hibiscus tea provides more antioxidants when prepared in the hot condition (7 min at 75 °C), and soon after cooled to 5 °C. Finally, it is recommended that hibiscus tea be consumed up to 24 h from preparation even when kept refrigerated.
This study aimed to evaluate the antimycotoxigenic effect of essential oils (EOs) obtained from four different aromatic plants on the production of deoxynivalenol (DON) and zearalenone (ZEA) by ...Fusarium graminearum. The EOs from ginger (GEO), turmeric (TEO), thyme (ThEO) and rosemary (REO) were obtained by hydrodistillation and identified by gas chromatography/mass spectrometry (GC/MS). The major compounds found were mostly monoterpenes and sesquiterpenes. The minimum inhibitory concentration (MIC) and minimum fungicide concentration (MFC) were 11.25, 364, 366 and 11,580 µg mL
−1
for ThEO, GEO, REO and TEO, respectively. The results evidenced that the assessed EOs inhibited DON and partially ZEA production by F. graminearum. ThEO and GEO were the EOs with most potent antimycotoxigenic action for DON and ZEA, respectively. These EOs have shown promising results in vitro regarding inhibition of mycotoxin production and might be used in the future as substitutes for synthetic fungicides.
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•Curcumin was nanoencapsulated with Pluronic® P123.•Cur/P123 associated with blue LED was effective in photoinactivation.•pH strongly interfered with photoinhibitory activity of ...Cur/P123.•Mixture design optimized the aPDT process.
Microbial contamination control is a public health concern and challenge for the food industry. Antimicrobial technologies employing natural agents may be useful in the food industry for these purposes. This work aimed to investigate the effect of photodynamic inactivation using curcumin in Pluronic® P123 nanoparticles (Cur/P123) at different pH and blue LED light against Staphylococcus aureus. Bacterial photoinactivation was conducted using different photosensitizer concentrations and exposure times at pH 5.0, 7.2 and 9.0. A mixture design was applied to evaluate the effects of exposure time (dark and light incubation) on the photoinhibitory effect. S. aureus was completely inactivated at pH 5.0 by combining low concentrations of Cur/P123 (7.80–30.25 μmol/L) and light doses (6.50–37.74 J/cm2). According to the mathematical model, dark incubation had low significance in bacterial inactivation at pH 5.0 and 9.0. No effect in bacterial inactivation was observed at pH 7.2. Cur/P123 with blue LED was effective in inactivating S. aureus. The antimicrobial effect of photodynamic inactivation was also pH-dependent.
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•HYP/P123 polymeric micelles for photoinactivation were formulated.•Association of HYP/P123 and low-intensity orange LED was effective in photoinactivation.•Mixture design determined ...Staphylococcus aureus reduction times.•HYP/P123 formulations did not photoinhibit biofilms.
Photoinactivation is a promising technique for Staphylococcus aureus control. This microorganism causes foodborne diseases (DTAs) and forms biofilms that are highly resistant and difficult to eradicate. Thus, the aim of this study was to evaluate the photodynamic activity of hypericin (HYP) in polymeric nanoparticles (Pluronic® P123) against S. aureus planktonic and biofilm cells. Planktonic cells and biofilms of S. aureus (ATCC 25923) were subjected to photoinactivation using low-power orange LED (0.3 mW/cm²) with different HYP formulation concentrations in Pluronic® P123. The P123 molar ratios were 2.5 (HYP/P123-2.5) and 10 (HYP/P123-10), respectively. The treatment times for planktonic cells were proposed by a mixture design, and bacterial photoinactivation was observed in concentrations of 12.5 to 3.12 μmol/L for HYP/P123-2.5 and reductions of ∼ 4.0 log CFU/mL in 12.5 to 0.78 μmol/L for HYP/P123-10. For biofilms, 30 min of darkness and 30 min of illumination were used. Maximum reductions were similar for both formulations and corresponded to approximately 0.9 log CFU/cm². It was concluded that photoinactivation with longer lighting times was effective against planktonic cells and could be potentially applied to control S. aureus.
Staphylococcus aureus is a global challenge to the clinical field and food industry. Therefore, the development of antimicrobial photodynamic therapy (aPDT) has become one of the valuable methods to ...control this pathogen. The antibacterial activity of photoinactivation by erythrosine (Ery) against S. aureus has been reported, but its modes of action are unclear. This study aimed to employ a proteomic approach to analyze modes of action of Ery-aPDT against S. aureus. We determined the antibacterial effect by Ery-aPDT assays, quantified reactive oxygen species (ROS) and injury to the cell membrane, and determined protein expression using a proteomic approach combined with bioinformatic tools. Ery-aPDT was effective in reducing S. aureus to undetectable levels. In addition, the increment of ROS accompanied the increase in the reduction of cell viability, and damage to cellular membranes was shown by sublethal injury. In proteomic analysis, we found 17 differentially expressed proteins. These proteins revealed changes mainly associated with defense to oxidative stress, energy metabolism, translation, and protein biosynthesis. Thus, these results suggest that the effectiveness of Ery-aPDT is due to multi-targets in the bacterial cell that cause the death of S. aureus.
