Juliana Antunes Galvão

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.

Características físico-químicas e microbiológicas (Staphylococcus aureus e Bacillus cereus) da água e dos mexilhões cultivados na região de Ubatuba, SP

Para efetivar o processamento dos mexilhoes, o monitoramento da qualidade da materia-prima compoe as exigencias de qualidade para comercializacao do produto. Objetivou-se com esta pesquisa diagnosticar parâmetros fisico quimicos e a incidencia de S. aureus e B. cereus tanto na agua de cultivo como no mexilhao. Na agua do mar foram analisados pH e turbidez. Nos mexilhoes, foram avaliados o pH e foi feito o exame biometrico das valvas. Foram realizadas analises de S. aureus e B. cereus tanto na agua quanto nos mexilhoes. O valor medio do pH da agua, dos respectivos pontos de coleta estudados, variou de 8,23 a 8,65, estando os dados encontrados nesta pesquisa de acordo com a legislacao (Brasil, 2001). Para a turbidez, a media geral das coletas ficou em torno de 0,67 UNT, alcancando picos de 1,15 UNT. Os valores de pH dos mexilhoes variaram de 5,66 a 6,81, estando 60% dos valores encontrados, dentro do limite estabelecido pela legislacao. Quanto a biometria das valvas, os valores medios ficaram enrte 4,78 a 7,81 cm. Para as analises microbiologicas, todas as amostras apresentaram-se dentro dos limites da legislacao. O B. cereus foi detectado na agua em apenas 6,7% das amostras. Os locais de cultivo apresentaram condicao sustentavel para cultivo e podem gerar alimento inocuo; os mexilhoes de cultivo podem ser utilizados como materia-prima na industria processadora.

Estabilidade físico-química e mercado do mexilhão (Perna perna) cultivado em Ubatuba - SP

This research work consisted of characterizing Perna perna mussel as a food in terms of its physicochemical stability, nutritional value and consumption. Specimens of the mussel were collected from three sites off the northern coast of the state of Sao Paulo, namely Barra Seca, Engenho da Almada and Costao do Cedro. The centesimal composition (humidity, crude protein, carbohydrates, lipids and ash), caloric value, pH and total basic volatile nitrogen were determined. A market study was also carried out based on a nonstructured questionnaire distributed to local tradesmen and consumers. The chemical constituents of the mussels were found to vary according to the season and their site of origin. These mussels are a source of protein (9.1 g.100 g –1) with a low lipid (1.1 g.100 g –1) and calorie content (72.7 Kcal.100 g –1). The specimens displayed physicochemical stability for 4 days at a temperature of 10 °C (p1), as evidenced by the physical and chemical results, which were noncorrelated. In general, businesses prefer to purchase shucked mussels and there was a higher demand for the product in the form of vinaigrette sauce. The consumer evinced unfamiliarity with the product, indicating the need for marketing efforts to promote it.

Use of smoking to add value to the salmoned trout

The objective of this study was to make a comparison between the characteristics of salmoned trout (Salmo truta) and salmon (Salmo salar) in terms of coloration (CIE L*a*b*), proximate composition, pH and sensory attributes of fresh and smoked fillets in order to obtain a possible alternative for the substitution of imported salmon for Brazilian salmoned trout as a commercial equivalent for retail sales. Results showed that no statistical difference was found for most of the sensory attributes analyzed and for pH. Although the coloration of the fillets presented a statistical difference, the trout presented a more intense coloration than the salmon, proving to be, therefore, convenient to agroindustry.

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

AbstractThe 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.

The Feasibility of Increasing Lipid Extraction in Tilapia (Oreochromis niloticus) Waste by Proteolysis

ABSTRACT The aim of the present study was to evaluate the feasibility of increasing lipid extraction in tilapia (Oreochromis niloticus) waste using different enzymes and to minimize the periods of hydrolysis to evaluate the performance of the lipid fractions. When processing waste tilapia, commercial enzymes were added that were composed of neutrase and alcalase acting at different hydrolysis times to produce the best yields. The treatment proved feasible for obtaining the protein hydrolysates. The type of enzyme and the hydrolysis time determined the degree of fractionation. The enzymes performed well, and the highest efficiency occurred within 2 h of hydrolysis. By fractionating, the obtained by-products can be applied in the preparation of feed, as the lipid fraction treatments yielded significant amounts of polyunsaturated fats and suitable n-6/n-3 ratios.

Contamination sources, biofilm-forming ability and biocide resistance of Staphylococcus aureus in tilapia-processing facilities

The major contamination sources, biofilm-forming ability and biocide resistance of Staphylococcus aureus in tilapia-processing plants were evaluated. Twenty-five processing control points were analysed twice in two factories, including whole tilapias, frozen fillets, water and food-contact surfaces. No final product was contaminated with S. aureus. However, high concentrations of S. aureus carrying enterotoxin (se) genes were found in several processing points of both factories due to the application of inadequate hygienic and handling procedures, which generate a high risk of cross-contamination of the tilapia fillets with staphylococcal enterotoxins. Nine S. aureus strains were characterized by RAPD-PCR using primers AP-7, ERIC-2 and S. A wide diversity of se gene profiles was detected, most strains being multi-se-carriers. All S. aureus strains showed high biofilm-forming ability on stainless steel and polystyrene. Biofilm-forming ability was correlated with the presence of fliC H7 and the type of origin surface (metallic or plastic). A marked resistance of S. aureus to peracetic acid and sodium hypochlorite was also observed, required doses being higher than those recommended by manufacturers to be eradicated. 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 that avoid, or at least reduce, the presence of bacterial pathogens and the emergence of antimicrobial resistance.

Application of exploratory factor analysis to assess fish consumption in a university community

The objective of this research was to use the technique of Exploratory Factor Analysis (EFA) for the adequacy of a tool for the assessment of fish consumption and the characteristics involved in this process. Data were collected during a campaign to encourage fish consumption in Brazil with the voluntarily participation of members of a university community. An assessment instrument consisting of multiple-choice questions and a five-point Likert scale was designed and used to measure the importance of certain attributes that influence the choice and consumption of fish. This study sample was composed of of 224 individuals, the majority were women (65.6%). With regard to the frequency of fish consumption, 37.67% of the volunteers interviewed said they consume the product two or three times a month, and 29.6% once a week. The Exploratory Factor Analysis (EFA) was used to group the variables; the extraction was made using the principal components and the rotation using the Quartimax method. The results show clusters in two main constructs, quality and consumption with Cronbach Alpha coefficients of 0.75 and 0.69, respectively, indicating good internal consistency.

The Perception of Consumers Vis-à-Vis Tracked Fish Measured via Electronic Instrument

Abstract Food traceability has been used to monitor production processes, and provide identification and information about sources and processes through computer technology. Technology also allows the recall of suspecting products identifying potential failures during their production. In this chapter, we discuss the impact of implementing the tracking technology into the Brazilian and Portuguese fish production chain and its impact on consumers’ attitudes using data collection through the Internet. The data collected allowed evaluating the initiative to track fish. The results showed that for 73.23% of participants, fish tracking was good and very good, and of this total, 82.19% are willing to pay more for a product with origin guarantee, which may indicate a market trend in search of a product with origin guarantee. The results also provided subsidies for the adoption of policies to implement a traceability system for fish to boost consumption.

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.