The thermal and chemical-based methods applied for microbial control in the food industry are not always environmentally friendly and may change the nutritional and organoleptic characteristics of ...the final products. Moreover, the efficacy of sanitizing agents may be reduced when microbial cells are enclosed in biofilms. The objective of this study was to investigate the effect of photodynamic inactivation, using two xanthene dyes (rose bengal and erythrosine) as photosensitizing agents and green LED as a light source, against
,
,
and
in both planktonic and biofilm states. Both photosensitizing agents were able to control planktonic cells of all bacteria tested. The treatments altered the physicochemical properties of cells surface and also induced potassium leakage, indicating damage of cell membranes. Although higher concentrations of the photosensitizing agents (ranging from 0.01 to 50.0 μmol/L) were needed to be applied, the culturability of biofilm cells was reduced to undetectable levels. This finding was confirmed by the live/dead staining, where propidium iodide-labeled bacteria numbers reached up to 100%. The overall results demonstrated that photoinactivation by rose bengal and erythrosine may be a powerful candidate for the control of planktonic cells and biofilms in the food sector.
Essential oils may be an alternative to the use of synthetic fungicides for the control of fungi involved in agricultural product deterioration. The aim of the present study was to evaluate the ...composition and antioxidant effect of turmeric essential oil and its antifungal and antimycotoxigenic action on Fusarium verticillioides (Sacc.) Nirenberg. The essential oil major components were α-turmerone (42.6%), β-turmerone (16.0%) and ar-turmerone (12.9%). The half-maximal inhibitory concentration (IC50) for the radical scavenging capacities of 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) were 0.54 and 10.03 mg/ml, respectively, indicating good antioxidant activity. The application of 17.9 and 294.9 μg/ml of turmeric essential oil decreased the development of F. verticillioides by 56.0 and 79.3%, respectively, when compared with the fungal control. The scanning electron microscopy demonstrated that the oil decreased the thickness and the length of the microconidia. Ergosterol production significantly decreased (p < 0.05) in groups treated with the essential oil relative to the control, indicating an effect of the oil on fungal biomass. The production of B1 and B2 fumonisins was significantly inhibited (p < 0.05) in groups treated with the essential oil. The results suggest that turmeric essential oil has antioxidant, antifungal and antimycotoxigenic activities.
•The essential oil of Curcuma longa exhibited chemopreventive effects.•The essential oil (EO) possesses good antioxidant activity.•The EO exhibited strong antifungal activity against F. verticillioides.•Turmeric essential oil inhibited the production of fumonisins.•The EO could be used as a potential source of eco-friendly preservatives.
Foodborne microbial diseases are still considered a growing public health problem worldwide despite the global continuous efforts to ensure food safety. The traditional chemical and thermal-based ...procedures applied for microbial growth control in the food industry can change the food matrix and lead to antimicrobial resistance. Moreover, currently applied disinfectants have limited efficiency against biofilms. Therefore, antimicrobial photodynamic therapy (aPDT) has become a novel alternative for controlling foodborne pathogenic bacteria in both planktonic and sessile states. The use of aPDT in the food sector is attractive as it is less likely to cause antimicrobial resistance and it does not promote undesirable nutritional and sensory changes in the food matrix. In this review, aspects on the antimicrobial photodynamic technology applied against foodborne pathogenic bacteria and studied in recent years are presented. The application of photodynamic inactivation as an antibiofilm strategy is also reviewed.
The present study evaluated the efficacy of photodynamic inactivation (PDI) of foodborne and spoilage bacteria using curcumin and a blue light emitting diode (LED). Curcumin at 75 μM was used to ...photo-irradiate Staphylococcus aureus ATCC 25923, Aeromonas hydrophila ATCC 7966, Salmonella Typhimurium ATCC 14028, Escherichia coli ATCC 25922 and Pseudomonas aeruginosa ATCC 27853 at light doses of 139 J/cm2, 278 J/cm2 and 417 J/cm2. The cytotoxicity of curcumin in VERO cells was evaluated in similar conditions to bacterial photoinactivation assay, and the percentage of cell destruction was ≅ 13 ± 0.05%, for all light doses. Curcumin-mediated PDI of S. aureus induced a significant reduction of approximately 3.50 log CFU/ml at 139 J/cm2 and 278 J/cm2. Full inactivation was observed at 417 J/cm2. Among Gram negative bacteria, P. aeruginosa was the least susceptible to PDI, which counts were not significantly reduced. A significant reduction in E. coli counts was observed at 278 J/cm2, and no viable cells were detected after light exposure at 417 J/cm2. When photo-irradiated with curcumin at 278 J/cm2 and 417 J/cm2, A. hydrophila was completely eradicated, while a significant decrease (3.33log CFU/ml) was observed in bacterial counts at 139 J/cm2. Curcumin in combination with a blue LED is a potential candidate for PDI against Gram positive and Gram negative bacteria.
•Bacterial viability was reduced after exposure to curcumin at 75 μM and LED light doses of 139 J/cm2, 278 J/cm2 and 417 J/cm2.•Aeromonas hydrophila displayed more sensibility to the treatment than other Gram negative bacteria.•Pseudomonas aeruginosa was the most resistant to photodynamic inactivation mediated by curcumin.
•Chemopreventive effect of the essential oil of Z. officinale.•We evaluate the antimycotoxigenic activities of the essential oil of Z. officinale.•Results indicate that the essential oil inhibited ...the toxin production.•Essential oil tested could be used to control the presence of F. verticillioides.
The antifungal activity of ginger essential oil (GEO; Zingiber officinale Roscoe) was evaluated against Fusarium verticillioides (Saccardo) Nirenberg. The minimum inhibitory concentration (MIC) of GEO was determined by micro-broth dilution. The effects of GEO on fumonisin and ergosterol production were evaluated at concentrations of 500–5000μg/mL in liquid medium with a 5mm diameter mycelial disc of F. verticillioides. Gas chromatography–mass spectrometry showed that the predominant components of GEO were α-zingiberene (23.9%) and citral (21.7%). GEO exhibited inhibitory activity, with a MIC of 2500μg/mL, and 4000 and 5000μg/mL reduced ergosterol biosynthesis by 57% and 100%, respectively. The inhibitory effect on fumonisin B1 (FB1) and fumonisin B2 (FB2) production was significant at GEO concentrations of 4000 and 2000μg/mL, respectively. Thus, the inhibition of fungal biomass and fumonisin production was dependent on the concentration of GEO. These results suggest that GEO was able to control the growth of F. verticillioides and subsequent fumonisin production.
The purpose of the present study was to evaluate the efficacy of photodynamic inactivation (PDI) mediated by erythrosine (ERY) and its ester derivatives erythrosine methyl ester (ERYMET) and ...erythrosine butyl ester (ERYBUT) on foodborne pathogens and spoilage bacteria. We evaluated Staphylococcus aureus ATCC 25923, Aeromonas hydrophila ATCC 7966, Salmonella enterica serotype Typhimurium ATCC 14028, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The toxicity of all of the compounds was assessed in VERO cells. PDI mediated by ERY and its derivatives combined with a light-emitting diode was performed at different concentrations and exposure times. S. aureus was more photosensitive than Gram-negative bacteria to ERY, ERYMET, and ERYBUT. The ERY-mediated PDI of S. aureus induced a significant reduction of 4.0 log CFU/ml at a light dose of 40 J/cm². ERYMET and ERYBUT at lower light doses than ERY completely eradicated S. aureus. When photoirradiated with ERY at light doses of 156 and 234 J/cm², A. hydrophila was completely eradicated. ERYBUT was more efficient in the PDI of A. hydrophila than ERYMET, even at 1 x 10⁻⁵ M and lower light doses. Salmonella Typhimurium, E. coli, and P. aeruginosa required higher concentrations of photosensitizers to reduce cell survival. ERYBUT and ERY may be promising photosensitizing agents against A. hydrophila and S. aureus. They were effective at reducing bacterial counts at nontoxic concentrations. The photoinactivation rate of the evaluated bacteria decreased in the following order: S. aureus > A. hydrophila > E. coli > S. Typhimurium > P. aeruginosa.
The present study evaluated the antibacterial and antibiofilm activity of carvacrol against Salmonella Typhimurium. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration ...(MBC) were determined and the time-kill curve and scanning electron microscopy (SEM) were performed to evaluate antibacterial activity. Antibiofilm activity was evaluated by quantifying total biomass using crystal violet assay, and metabolic activity was determined using MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The action of carvacrol against preformed biofilm on polypropylene and stainless steel was also evaluated by colony counting and SEM. The MIC and MBC was 312 µg mL-1. Carvacrol at MIC and 2 x MIC eliminated cells after 6 and 1 h of treatment, respectively, as exhibited in the time-kill curve. The greatest reduction in biofilm biomass and metabolic activity was 1,719 OD550 and 0,089 OD550 respectively, both at 4 x MIC of carvacrol. In carvacrol treated biofilms of S. Typhimurium on polypropylene, a reduction of 5.12 log was observed with 4 x MIC, while on stainless steel, carvacrol at 4 x MIC reduced bacterial counts by 5 log. The results showed that carvacrol exhibits antibacterial activity and can be used as an alternative for the control of S. Typhimurium biofilms.
•The essential oil of Thymus vulgaris exhibited strong antifungal activity.•Thyme essential oil caused leakage of the cytoplasm of A. flavus.•The results indicated that this essential oil inhibited ...the production of aflatoxins.•The essential oil could be used as a potential source of eco-friendly fungicides.•Essential oil tested could be used to control the presence of A. flavus.
The antifungal and antiaflatoxigenic properties of Thymus vulgaris essential oil (TEO) were evaluated upon Aspergillus flavus “in vitro”. Suspension containing 106 of A. flavus were cultivated with TEO in concentrations ranging from 50 to 500μg/mL. TEO reached minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) at 250μg/mL. Inhibition of ergosterol biosynthesis was detected at a concentration of 100μg/mL of TEO. Morphological evaluation performed by both light microscopy and scanning electron microscopy showed that antifungal activity of TEO could be detected starting at a concentration of 50μg/mL and the fungicide effect at a concentration of 250μg/mL. TEO completely inhibited production of both B1 and B2 aflatoxins (AFB1 and AFB2) at a concentration of 150μg/mL. This way, fungal biomass development and aflatoxin production were dependent on TEO concentration. Therefore, TEO was capable of controlling the growth of A. flavus and its production of aflatoxins.
•Carvacrol acetate was identified as the major compound of oregano essential oil.•Oregano essential oil presented antioxidant activity by the DPPH and ABTS methods.•Antimicrobial activity of ...essential oil was effective against A. acidoterrestris.•The use of this essential oil can be indicated as a natural preservative.
The Alicyclobacillus spp., causing deterioration in citrus beverages, has been frequently related to the use of natural antimicrobial agents in its combat; in this sense, the study sought to evaluate the activity of the essential oil of oregano (Origanum vulgare) against different isolates of this bacterium, in addition to its antioxidant activities. The minimum inhibitory concentration obtained from oregano essential oil for A. Acidiphilus and A. cycloheptanicus was 125 μg/mL; and for A. herbarius and A. acidoterrestris was 62.5 μg/mL. While the minimum bactericidal concentration obtained was 1000 μg / mL for all isolates. The combined effect of nisin and O. vulgare against A. acidoterrestris resulted in indifference. The antioxidant activity obtained was 363 μmol trolox/mg by the DPPH method and 1142 μmol trolox/mg by the ABTS method. The chemical characterization of the essential oil of oregano by GC–MS was able to identify of 93.13% of the compounds was carried out, where the major compound was carvacrol acetate represented by 59.61%. Further scanning electron microscopy was able to demonstrate damage to cells treated with the inhibitory concentrations of O. vulgare.
The objective of this research was to elaborate and characterize mortadella using fillet residues (‘V’-cut fillet trim) of Nile tilapia, in order to add value to this by-product of the filleting ...process. Three mortadellas were made, one with 100% tilapia fillet trimmings, another containing 100% chicken meat and the third with 100% pork meat. Mortadellae were characterized in terms of microbiology, chemical composition, calcium, collagen, pH, Aw, colour, texture and formulation cost. Mortadella was within the recommended microbiological standards. Tilapia mortadella had higher levels of moisture, ash, calcium and collagen, higher pH and lower water activity when compared to other species. The tilapia mortadella had lower brightness, higher chroma a * and intermediate chroma b *, compared with the others. The texture of tilapia mortadella was better in terms of hardness, gumminess and chewability, the values of which were lower. The chicken mortadella had a higher acceptance rate; however, that of tilapia was also high, while all evaluated attributes of pork received the worst grades. Nile tilapia mortadella is a technological innovation that can be introduced into the food sector with good nutritional value and a good acceptance index.
RESUMO: O objetivo deste trabalho foi elaborar e caracterizar mortadelas a partir de aparas da filetagem (corte em “V” do filé) de tilápia do Nilo, de forma a possibilitar a agregação de valor a este subproduto do processo de filetagem. Foram elaboradas três mortadelas, sendo uma com 100% de aparas da filetagem de tilápia, outra contendo 100% de carne de frango e a terceira com 100% de carne suína. As mortadelas foram caracterizadas quanto à microbiologia, composição química, cálcio, colágeno, pH, Aw, cor, textura e custo de formulação. As mortadelas estavam dentro dos padrões microbiológicos recomendados. A mortadela de tilápia apresentou maiores teores de umidade, cinzas, cálcio e colágeno, maior pH e menor atividade de água quando comparada às demais espécies. A mortadela de tilápia apresentou menor luminosidade, maior croma a* e croma b* intermediário às demais. A textura foi melhor para as mortadelas de tilápia, quanto a dureza, gomosidade e mastigabilidade, cujos valores foram menores. A mortadela de frango teve maior índice de aceitação, porém, a de tilápia também foi elevado, enquanto de suíno todos os atributos avaliados receberam as piores notas. A mortadela de tilápia do Nilo é uma inovação tecnológica que pode ser introduzida no setor alimentício com bom valor nutricional e bom índice de aceitação.
PDF
