RESUMO
This article presents results from a toxicity reduction evaluation program intended to describe wastewater from the metalworking industry that was treated using a conventional physico-chemical process. The toxicity of the wastewater for the microcrustacean Daphnia magna was predominantly expressive. Alkaline cyanide wastewater generated from electroplating accounted for the largest number of samples with expressive toxicity. When the raw wastewater concentrations in the batches were repeated, inexpressive toxicity variations were observed more frequently among the coagulated-flocculated samples. At the coagulation-flocculation step, 22.2 % of the treatments had reduced acute toxicity, 30.6 % showed increased toxicity, and 47.2 % remained unchanged. The conductivity and total dissolved solids contents of the wastewater indicated the presence of salts with charges that were inappropriate for the survival of daphnid. The wastewaters treated by neutralization and coagulation-flocculation had average metallic compound contents that were greater than the reference toxic concentrations reported in other studies, suggesting that metals likely contributed to the toxic effects of the wastewater on freshwater microcrustaceans. Thus, alternative coagulants and flocculants should be assessed, and feasible doses should be determined to improve wastewater treatment. In addition, advanced treatment processes should be assessed for their abilities to remove dissolved toxic salts and ions.
Assuntos
Monitoramento Ambiental/métodos , Metalurgia , Águas Residuárias/toxicidade , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos , Animais , Brasil , Fenômenos Químicos , Daphnia/efeitos dos fármacos , Floculação , Água DoceRESUMO
The present work was designed in order to obtain the cut off point, to be used in a shelf life study on whole stirred strawberry yogurt. The study was simultaneously carried out in Argentina, Chile and Costa Rica, assaying the same kind of product, elaborated in each one of the countries. The sensory quality parameters obtained from trained panelists and the consumers acceptability, were correlated by using the cut off point methodology through a quality evaluation by the Karlsruhe scale. According to preliminary studies, the storage at 42 degrees C produced considerable damage on parameters such as pH, acidity (volumetric assay), viscosity and sensory quality. For each sample, the cut off point was determined. This value corresponds to the threshold score for the sensory quality, where the consumer starts to perceive negative changes in the product, when comparing with the fresh product. The rejection percentage was also calculated according to the cut off point. The cut off points and the percentage of rejection obtained by the three participating countries were similar. Data obtained from Costa Rica showed changes in color, acidity and rancidity. Argentinean yogurts developed acidity that had a negative effect on texture, appearance and residual flavors. Chilean samples presented a sensory quality that remains almost without change through the studied time. The differences of the deterioration pattern amongst the three countries, demonstrates that the products are different in formulation and elaboration process, in spite of been the same kind of yogurt. This could be explained by differences specified in the regulation of each country.
Assuntos
Comportamento do Consumidor , Manipulação de Alimentos/métodos , Conservação de Alimentos , Paladar , Iogurte/normas , Adulto , Argentina , Chile , Costa Rica , Comparação Transcultural , Feminino , Inspeção de Alimentos , Fragaria , Humanos , Concentração de Íons de Hidrogênio , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Temperatura , Fatores de Tempo , Iogurte/microbiologiaRESUMO
Con el fin de estimar el punto de corte, para luego ser empleado en un estudio de vida útil de yogurt batido de fresa, se diseñó un estudio simultáneo, a ser realizado en Argentina, Chile y Costa Rica, con un mismo tipo de yogurt, elaborado en los respectivos países de origen, relacionándose los parámetros de calidad sensorial, determinados con un panel entrenado, y la aceptabilidad, determinada con consumidores. Para ello se empleó la metodología de punto de corte utilizando la valoración de calidad mediante el método de Karlsruhe. Estudios preliminares realizados a 42º C indicaron que los parámetros de calidad más sensibles al deterioro por efecto del almacenamiento eran: pH, acidez titulable, viscosidad y la calidad sensorial. En cada caso se determinó el punto de corte que representa el puntaje de calidad sensorial a partir del cual el consumidor comienza a percibir un cambio en el producto, en relación al producto fresco y también se calculó el porcentaje de rechazo en función del punto de corte. Los puntos de corte y los porcentajes de rechazo obtenidos para los tres países fueron similares, pero a nivel de calidad sensorial, las muestras de yogurt costarricenses modificaron sus características de coloración y sabores ácido y rancio, las muestras de yogurt argentino desarrollaron acidez que influenció cambios en la textura, apariencia y sabores residuales y las muestras de yogures chilenos fueron las que se mantuvieron más estables en su calidad sensorial, a través del tiempo. Esta disparidad en el comportamiento de las muestras evidencia que los productos, a pesar de tener una misma denominación, corresponden a productos diferentes en su formulación y elaboración, la cual está supeditada a la diferente reglamentación vigente en cada país. Así por ejemplo, las condiciones de comercialización son también diferentes, por lo que la industria local debe satisfacer las necesidades de esa población y considerar las variables que definen la aceptación del producto en cada mercado objetivo