Anti-biofilm efficacy of single and binary treatments based on plant essential oils against Escherichia coli persistent in food-processing facilities.

The efficacy of single and combined treatments based on plant essential oils was investigated against Escherichia coli strains persistent in food-processing facilities. Surface materials (stainless steel and polystyrene), disinfectants (peracetic acid and sodium hypochlorite), and conditions (25 ℃, frequency of sanitizing of 24 h) commonly present in the food industry were also used to reach a more realistic approach. Thyme and pepper-rosmarin oils were significantly (P < 0.05) very effective against planktonic cells and biofilms formed by strains E6 and E7, respectively, followed by peracetic acid. Meanwhile, craveiro oil showed an efficacy that is significantly (P < 0.05) higher than sodium hypochlorite. All these disinfectants except sodium hypochlorite were able to kill 99.99% of biofilm cells in the range of concentrations tested (0.1%-3% v/v). However, binary treatments were needed to decrease the doses of these essential oils significantly (P < 0.05) for the control of E. coli biofilms. The effectiveness of peracetic acid against E. coli biofilms was also improved by blending with these essential oils. In particular, blends of pepper-rosmarin with thyme or peracetic acid demonstrated a suitable effectiveness for the control of persistent E. coli present in food-related environments. The application of these treatments could also reduce the current environmental impact generated during food-processing sanitization.

Control of Staphylococcus aureus biofilms by the application of single and combined treatments based in plant essential oils.

Effective and environmentally-friendly alternatives to traditional disinfectants are necessary to reduce the pollution and the emergence of antimicrobial-resistant bacterial strains in food-related environments. In the present study, treatments based in single and combined applications of plant essential oils (EOs) were evaluated for control Staphylococcus aureus biofilms. EOs of Lippia sidoides, Thymus vulgaris and Pimenta pseudochariophyllus showed a higher efficacy than peracetic acid and sodium hypochlorite against S. aureus planktonic cells and 24-h-old biofilms formed on polystyrene and stainless steel under food-related conditions. High concentrations of thymol and chavibetol were detected in these EOs, as well as the presence of other antimicrobial compounds such as carvacrol, eugenol, p-cymene, limonene, α-pinene, α-terpineol, terpinen-4-oil and linalool. L. sidoides oil were particularly effective against S. aureus, but doses higher than 2.75% (v/v) were required to completely eradicate 24-h-old biofilms. Binary combinations of L. sidoides, T. vulgaris and P. pseudochariophyllus allowed decrease significantly doses required to reduce 99.99% the number of biofilm cells. Furthermore, peracetic acid increased its efficacy against S. aureus biofilms by the combined application with these EOs. The most effective treatments against S. aureus biofilms were those combining L. sidoides with T. vulgaris or peracetic acid. Therefore, these EO-based treatments can be considered as an effective and environmentally-friendly alternative to control S. aureus biofilms in food-contact surfaces.

Contamination sources, serogroups, biofilm-forming ability and biocide resistance of Listeria monocytogenes persistent in tilapia-processing facilities.

The major contamination sources, serogroups, biofilm-forming ability and biocide resistance of Listeria monocytogenes persistent in tilapia-processing facilities were assessed. Twenty-five processing-control points were examined twice in two factories, including whole tilapias, frozen fillets, water and food-contact surfaces. L. monocytogenes were detected in 4 and 20% of points of Factory A and B respectively, but at low concentrations. Contamination was due to inadequate handling of tilapias in the slaughter room of Factory A and to the application of ineffective sanitizing procedures in Factory B. Seven strains were characterized by RAPD-PCR using primers HLWL85, OPM-01 and DAF4. Genotypic similarity allowed tracing the contamination source of tilapia fillets in Factory B and detecting a prevalent strain in Brazilian tilapia-processing facilities. The serogroup II (including the serotype 1/2c) was the most frequently found, followed by serogroup I (1/2a) and III (1/2b), whereas the serotype 4b was not detected. All strains showed high biofilm-forming ability on stainless steel and polystyrene, but biofilm formation was positively correlated with the type of origin surface. Biofilms were highly resistant to peracetic acid and sodium hypochlorite, being required doses higher than those recommended by manufacturers to be eradicated. Peracetic acid was more effective than sodium hypochlorite, but the use of disinfectants with similar mechanisms of action increases the risk of cross-resistance. Case-by-case approaches are thus recommended to determine the sources and degree of contamination present in each factory, which would allow applying precise responses to control the persistence of bacterial pathogens such as L. monocytogenes.

Availability and consumption of fish as convenience food - correlation between market value and nutritional parameters

Abstract Fish consumption is low in Brazil and several factors justify this fact, among them the lack of practicality in preparation. Thus, this study aimed to investigate the relation between the price and the nutritional characteristics of the processed fish products. Correlations between price and nutritional value of 18 different processed fish products were established, comparing nutritional parameters between in natura and processed fish. The results showed that protein features moderate positive correlation to price. The processed fish products analyzed showed lower protein content and higher contents of energy, lipids and sodium compared to in natura fish.

LABEL DESIGNING FOR MINIMALLY PROCESSED TILAPIA AIMING THE TRACEABILITY OF THE PRODUCTIVE CHAIN

The aim of this study was to develop label for Nile tilapia minimally processed. Analyses were performed to quantify the nutritional components of the fillets; and information about freshness, date of processing and batch specification was collected. Such data were essential for designing labels providing information about the traceability system and presenting codes for quality identification such as the Quick Response Code (QR Code), which allows the electronic encoding of the product on a database. Mandatory food labeling associated with the use of QR Code are tools that convey information to consumers about food quality and the entire production chain. One hundred sixty-two potential consumers were surveyed about the general characteristics of the product packaged in poly nylon film type, vacuum-packed, used for the packaging of traced fresh-cut fillets of tilapia minimally processed and kept under refrigeration (0±1oC). According to the Spearman correlation the variables packaging, general appearance and willingness to purchase the product presented a correlation, with coefficients estimated at 0.437, 0.466 and 0.497 respectively.

Saxitoxins accumulation by freshwater tilapia (Oreochromis niloticus) for human consumption.

The accumulation of saxitoxins (STXs) in fish from freshwater aquaculture was investigated for the first time in the present study. Cyanotoxins have been monitored in liver and muscle samples of Oreochromis niloticus by chromatographic methods, both before and after the depuration process. The results show that tilapia can accumulate STXs. Our findings suggest that depuration with clean water is an alternative process to eliminate STXs from fish and, therefore, improve the safety of tilapia for consumers.

Use of smoking to add value to the salmoned trout

O objetivo deste estudo foi comparar as características inerentes à truta salmonada (Salmo truta) e ao salmão (Salmo salar), no que se refere à coloração (CIE L*a*b*), composição centesimal, pH e atributos sensoriais, de filés in natura e defumados, visando uma possível alternativa para substituição do salmão importado pela truta salmonada brasileira, em termos de equivalência comercial para venda no varejo. Os resultados encontrados, mostraram que não ocorreu diferença estatística para a maioria dos atributos sensorias analisados e para o pH. Já a coloração dos filés apresentou diferença estatística indicando porém, uma coloração mais intensa para a truta em relação ao salmão, sendo, portanto, conveniente à agroindústria.