Psychophysical estimation of acid intensity and determination of sweet-acid interaction in a fish paste containing glycerol

In a fish paste made with cooked Brazilian flathead (Percophis brasiliensis), glycerol (17%), sodium chloride (1.5%) and potassium sorbate (0.1%) the following acid percentages: 0.2; 0.4; 0.6; 0.8, 1 and 1.5% w/w were incorporated to determine the relationship between added acetic acid and the sensorially perceived intensity, and the effects of the combination of sweet-acid tastes. Tests for paired comparison, ranking and structured verbal scales for sweet and acid attributes and psychophysical test were carried out. There was a perceptible difference among samples for differences of 0.4 units of acid concentration. Samples indicated as sweeter by 89.47% of the judges were those containing a lesser acid concentration. A reduction in glycerol sweetness when increasing acid levels was observed. Acetic acid reduced the sweetness of glycerol and inversely glycerol reduced the acidity of acetic acid. The data obtained with the magnitude estimation test agree with Steven’s law.Foram incorporados glicerol (17%), cloreto de sódio (1,5%) e sorbato de potássio (0.1%) nas seguintes porcentagens de ácido: 0,2; 0,4; 0,6; 0,8; 1 e 1,5% p/p, em um patê elaborado a partir de congro-real (Percophis brasiliensis) cozido, com o intuito de determinar a relação entre o ácido acético adicionado e a intensidade sensorialmente percebida, assim como o efeito da combinação dos gostos doce e ácido. Foram realizados testes de comparação pareada, de classificação e também estruturada uma escala verbal para os atributos ácido e doce, e testes psicofísicos. Foi percebida diferença entre as amostras com diferença de 0,4 unidades de concentração de ácido. As amostras indicadas como as mais doces por 89,47% dos julgadores foram as que continham menor concentração de ácido. Foi observada a redução da doçura do glicerol quando aumentaram os níveis de ácido. O ácido acético reduziu a doçura do glicerol e, inversamente, o glicerol reduziu a acidez do ácido acético. Os dados obtidos com o teste de estimação de magnitude concordaram com a lei de Steven

Mass Transfer During Osmotic Dehydration of Chub Mackerel Cylinders in Ternary Solution

In the analysis, design and optimization of an osmotic dehydration process is important to know the kinetic of water loss and solutes gain. In this study, the mass transfer during osmotic dehydration of chub mackerel (Scomber japonicus) cylinders in ternary solution glycerol/salt/water was analyzed. The models of Zugarramurdi & Lupín and Azuara were used to describe mass transfer and to estimate equilibrium values. The radial effective diffusion coefficient was estimated using the analytical solution of Fick's second law. Diffusion coefficients were determined for a finite cylinder, for an infinite cylinder considering only the first term of the series and considering higher order terms of the series. The profiles of water and solutes during the osmotic dehydration were calculated by using the estimated water and solutes diffusivities. According to the results obtained, using three terms in the analytical solution of the Fick's second law is appropriate to determine the diffusion coefficients. The diffusion coefficient for infinite cylinder were 2.63×10-6, 4.11×10-6 and 4.25×10-6 cm2/s for water loss, salt and glycerol gain respectively. For a finite cylinder these values were 2.30×10-6, 3.67×10-6 and 3.78×10-6 cm2/s respectively. All the models proposed were in agreement with experimental data for solutes gain ((0.967<R2adj<0.986); (0.0016<RMSE<0.039) and (4.17<P<10.0)). The model based on the solution of Fick’s Law for an infinite cylinder with higher order terms was the best fit for water loss and solutes gain. The equilibrium values estimated with Azuara model agree with the experimental (0<relative error<9.8). Water and solute distributions as a function of time and location in the radial direction were plottedCentro de Investigación y Desarrollo en Criotecnología de AlimentosConsejo Nacional de Investigaciones Científicas y Técnica

Mass Transfer During Osmotic Dehydration of Chub Mackerel Cylinders in Ternary Solution

In the analysis, design and optimization of an osmotic dehydration process is important to know the kinetic of water loss and solutes gain. In this study, the mass transfer during osmotic dehydration of chub mackerel (Scomber japonicus) cylinders in ternary solution glycerol/salt/water was analyzed. The models of Zugarramurdi & Lupín and Azuara were used to describe mass transfer and to estimate equilibrium values. The radial effective diffusion coefficient was estimated using the analytical solution of Fick's second law. Diffusion coefficients were determined for a finite cylinder, for an infinite cylinder considering only the first term of the series and considering higher order terms of the series. The profiles of water and solutes during the osmotic dehydration were calculated by using the estimated water and solutes diffusivities. According to the results obtained, using three terms in the analytical solution of the Fick's second law is appropriate to determine the diffusion coefficients. The diffusion coefficient for infinite cylinder were 2.63×10-6, 4.11×10-6 and 4.25×10-6 cm2/s for water loss, salt and glycerol gain respectively. For a finite cylinder these values were 2.30×10-6, 3.67×10-6 and 3.78×10-6 cm2/s respectively. All the models proposed were in agreement with experimental data for solutes gain ((0.967<R2adj<0.986); (0.0016<RMSE<0.039) and (4.17<P<10.0)). The model based on the solution of Fick’s Law for an infinite cylinder with higher order terms was the best fit for water loss and solutes gain. The equilibrium values estimated with Azuara model agree with the experimental (0<relative error<9.8). Water and solute distributions as a function of time and location in the radial direction were plottedCentro de Investigación y Desarrollo en Criotecnología de AlimentosConsejo Nacional de Investigaciones Científicas y Técnica

Monitoring the characteristics of cultivable halophilic microbial community during salted-ripened anchovy (<i>Engraulis anchoita</i>) production

The halophilic microbial community of the salted-ripened anchovy process was studied. Samples from raw materials (salt and fresh anchovies) and from the stages of brining and ripening were collected and analyzed for their bacterial counts at 15 and 20% NaCl. No halophilic colonies were found in fresh anchovy and counts of about 103 CFU/g were determined in salt samples. A fluctuation of bacterial counts during the process was found. At the end of brining, ~104 CFU/g were determined in anchovy samples and this value was reduced to not detectable counts at the beginning of the ripening stage. After one month, counts increased to ~104 CFU/g and remained stable until the end of the process. From each sample, colonies having different morphotypes were isolated and submitted to a macro and microscopic characterization, a study of salt requirement for growth, and biochemical and phenotypic tests. The results were submitted to Univariate, Bivariate and Multiple Correspondence Factorial Analysis (MCFA). A total of 79 colonies were isolated during the salting-ripening anchovy process. Among the isolates, about 40–50% was positive for indole production and lipolytic activity and a 25% showed ability to produce H2S and proteolytic capacity. Proteolytic and lipolytic activities were well balanced along the process and resulted independent from the isolation stage, which is a desirable condition due to the contribution of microbial proteolysis and lipolysis to the development of texture and final aroma, respectively. H2S and indole producers practically were not detected during ripening. This fact is important because indole and H2S are associated with the development of off-flavors and spoilage in salted fish products. MFCA and Cluster Analyses complemented the Bivariate Analyses. The factor map showed proximity between the isolates from salt samples and from ripening. Isolates were statistically clustered in two groups. Cluster 1 grouped non-desirable activities (H2S and indole production) with cultures proceeding from brining whereas Cluster 2 related isolates mainly from salt samples and during ripening with some desirable microbial capacities (Cytochrome oxidase activity and non-H2S and non-indole production). These results would indicate that during the ripening process of salted anchovies, a natural selection of beneficial microorganisms for the development of the typical product sensory attributes occurred.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de IngenieríaComisión de Investigaciones Científicas de la provincia de Buenos Aire

Lomitos de caballa preservados mediante tecnología de obstáculos

El objetivo de este trabajo fue diseñar una preserva de caballa de humedad intermedia mediante combinación de barreras de estrés microbiano. Las barreras utilizadas fueron: disminución de la carga bacteriana e inactivación enzimática por cocción al vapor disminución de la actividad de agua, envasado al vacío en películas impermeables al O2, tratamiento térmico moderado y almacenamiento en refrigeración. Los troncos de caballa se cocinaron al vapor durante 20 minutos, se dejaron orear en refrigeración y se eliminó la piel, espinas y músculo rojo. Los lomitos se deshidrataron osmóticamente en una solución de glicerol y sal (aw=0,64) durante 19 hs en refrigeración, se envasaron al vacío en bolsas termosellables de polietileno de baja densidad y poliamida y se pasteurizaron a 60 °C durante 50 minutos (con Staphylococcus aureus como microorganismo de control). Luego de la pasteurización se enfriaron y se almacenaron en refrigeración (5 °C). La preserva tuvo una aw de 0,89, un pH de 5,5 y un contenido de agua de 49,70 %. Los lomitos se analizaron el día de su preparación, semanalmente durante el primer mes y mensualmente durante 11 meses. Se realizaron análisis fisicoquímicos (aw y contenido de agua), análisis microbiológicos (recuento total de microorganismos psicrótrofos, mesófilos, clostridios sulfito reductores y Staphylococcus spp) y análisis sensoriales (color y aroma rancio). No se detectó crecimiento microbiano y los parámetros sensoriales y fisicoquímicos se mantuvieron sin variación durante todo el tiempo de almacenamiento. Se diseño satisfactoriamente una preserva de caballa mediante el uso de la tecnología de obstáculos.Facultad de Ciencias ExactasCentro de Investigación y Desarrollo en Criotecnología de Alimento

Osmotic dehydration of mackerel (Scomber Japonicus) fillets by means of binary and ternary solutions

Osmotic dehydration of mackerel fillets was achieved by immersing them in binary and ternary solutions (NaCl/water or NaCl/sucrose/water). The kinetics of water loss and NaCl and sucrose gains were studied, as well as the accuracy of empirical models to explain these experimental behaviours. The results show how the presence of both solutes can enhance water loss and also interfere in each other’s diffusion. Among the three empirical models analyzed, Peleg’s equation proves to be the most suitable (R2&gt;0.836) to describe all the mass transfer process. A modified Peleg’s model was also obtained with a high performance to describe the relationship between water content of mackerel fillets and sucrose and NaCl concentration in binary and ternary solutions.Centro de Investigación y Desarrollo en Criotecnología de Alimento

Monitoring the characteristics of cultivable halophilic microbial community during salted-ripened anchovy (<i>Engraulis anchoita</i>) production

The halophilic microbial community of the salted-ripened anchovy process was studied. Samples from raw materials (salt and fresh anchovies) and from the stages of brining and ripening were collected and analyzed for their bacterial counts at 15 and 20% NaCl. No halophilic colonies were found in fresh anchovy and counts of about 103 CFU/g were determined in salt samples. A fluctuation of bacterial counts during the process was found. At the end of brining, ~104 CFU/g were determined in anchovy samples and this value was reduced to not detectable counts at the beginning of the ripening stage. After one month, counts increased to ~104 CFU/g and remained stable until the end of the process. From each sample, colonies having different morphotypes were isolated and submitted to a macro and microscopic characterization, a study of salt requirement for growth, and biochemical and phenotypic tests. The results were submitted to Univariate, Bivariate and Multiple Correspondence Factorial Analysis (MCFA). A total of 79 colonies were isolated during the salting-ripening anchovy process. Among the isolates, about 40–50% was positive for indole production and lipolytic activity and a 25% showed ability to produce H2S and proteolytic capacity. Proteolytic and lipolytic activities were well balanced along the process and resulted independent from the isolation stage, which is a desirable condition due to the contribution of microbial proteolysis and lipolysis to the development of texture and final aroma, respectively. H2S and indole producers practically were not detected during ripening. This fact is important because indole and H2S are associated with the development of off-flavors and spoilage in salted fish products. MFCA and Cluster Analyses complemented the Bivariate Analyses. The factor map showed proximity between the isolates from salt samples and from ripening. Isolates were statistically clustered in two groups. Cluster 1 grouped non-desirable activities (H2S and indole production) with cultures proceeding from brining whereas Cluster 2 related isolates mainly from salt samples and during ripening with some desirable microbial capacities (Cytochrome oxidase activity and non-H2S and non-indole production). These results would indicate that during the ripening process of salted anchovies, a natural selection of beneficial microorganisms for the development of the typical product sensory attributes occurred.Centro de Investigación y Desarrollo en Criotecnología de AlimentosFacultad de IngenieríaComisión de Investigaciones Científicas de la provincia de Buenos Aire

Investigation of Halococcus morrhuae in salted-ripened anchovy products

In this work, the incidence of H. morrhuae in salted-ripened anchovy products was assessed. Moreover, the microbial biochemical activity possible related with sensorial and physicochemical changes that takes place during the process was explored. A type strain of H. morrhuae (ATCC 17082) was used as reference and a detailed phenotypic characterization of the species was carried out. Samples of salted-ripened anchovy taken from barrels at the end of ripening (78) and fillets of salted-ripened anchovy (22) were analysed for microbial counts and isolation of presumptively H. morrhuae colonies. Cluster analysis of the biochemical tests revealed that none of the 38 isolated strains with colony morphology and cell arrangement similar to the type strain would be classified as H. morrhuae. However, a number of the isolated strains were very closely related with the H. morrhuae type strain, for which it could correspond other species of the genus Halocuccus. A remarkable result is that a high percentage of the isolates were proteolytic and/or lypolitic, capable to decarboxylase amino acids and produce indol and H2S. These activities, depending on the intensity, can be directly related with the expected physicochemical changes that occur during ripening or even with quality loss and spoilage.Fil: Felix, Mónica María Leonor. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química. Grupo de Investigación en Preservación y Calidad de Alimentos; ArgentinaFil: Czerner, Marina. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química. Grupo de Investigación en Preservación y Calidad de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Ameztoy, Irene Mabel. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química. Grupo de Investigación en Preservación y Calidad de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Ramírez, Élida Beatriz. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química. Grupo de Investigación en Preservación y Calidad de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; ArgentinaFil: Yeannes, Maria Isabel. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Departamento de Ingeniería Química. Grupo de Investigación en Preservación y Calidad de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin