Cheese freezing by immersion in concentrated aqueous solutions

La congelación de quesos ha sido usada para prolongar su vida útil y extender su comercialización a lugares distantes. Los quesos blandos representan el segmento de mayor dinamismo e innovación tecnológica. En el caso de queso Mozzarella, su congelación por inmersión en soluciones de NaCl podría ser una alternativa interesante para disminuir el efecto de la congelación sobre la calidad final del queso y para disminuir el tiempo de procesamiento ya que los procesos de salado y congelación ocurren simultáneamente. El objetivo principal de esta Tesis fue evaluar el efecto de la congelación por inmersión y del almacenamiento de las muestras congeladas sobre las principales propiedades fisicoquímicas, bioquímicas, reológicas y estructurales de queso Mozzarella. En el diseño experimental principal, se usaron placas de queso (dimensiones: 2x10x10 cm3), las que fueron sumergidas en soluciones de NaCl 23% p/p (muestras control: 4°C, 90 min; muestras congeladas y muestras almacenadas congeladas: –15°C, 180 min). Las muestras almacenadas congeladas fueron mantenidas a –20°C durante 2 meses y luego se descongelaron a 4°C. Todas las muestras fueron envasadas al vacío y almacenadas a 4°C para su maduración. Se evaluaron propiedades fisicoquímicas, bioquímicas, reológicas y estructurales de muestras de cada tratamiento a los 1, 7, 14, 20, 27, 34 y 41 días de maduración. Si bien la congelación por inmersión afectó estadísticamente algunos de los parámetros estudiados, las diferencias observadas son pequeñas, por lo que se considera que el proceso de congelación por inmersión podría ser muy útil para la elaboración y conservación del queso Mozzarella.The freezing of cheeses has been used to extend its shelf-life and to expand its commercialization to distant places. The soft cheeses represent the sector with the highest dynamism and technological innovation. In the case of Mozzarella cheese, its freezing by immersion in NaCl solutions may be an innovative procedure for the dairy industry to reduce the effect of freezing on the final cheese quality, and to reduce the processing time because it combines conveniently salting and freezing processes. The main objective of this thesis was to evaluate the influence of this type of freezing method and of the frozen storage of samples on the main physicochemical, biochemical, rheological and structural properties of Mozzarella cheese. In the main experimental design, cheese slabs (dimensions: 2x10x10 cm3) were immersed in 23% NaCl solutions (control samples: 4ºC, 90 min; frozen and frozen-stored samples: -15ºC, 180 min). The frozen-stored samples were stored at -20ºC for 2 months and then thawed at 4ºC. The samples were stored at 4ºC and assayed at 1, 7, 14, 20, 27, 34, and 41 days to evaluate physicochemical, biochemical, rheological and structural properties. Although the immersion freezing of Mozzarella cheese affects some of the studied parameters, the differences observed were small. Therefore, it was considered that the immersion freezing could be useful for the manufacture and preservation of Mozzarella cheese.Consejo Nacional de Investigaciones Científicas y TécnicasAgencia Nacional de Promoción Científica y TecnológicaUniversidad Nacional del LitoralFundación Antorcha

Influence of Immersion Freezing in NaCl Solutions and of Frozen Storage on the Viscoelastic Behavior of Mozzarella Cheese

The freezing of Mozzarella cheese by immersion in NaCl solutions may be an innovative procedure for the dairy industry because combines conveniently salting and freezing processes. In this work, the influence of this type of freezing method and of the frozen storage of samples on the viscoelastic behavior of Mozzarella cheese was studied. Slabs (2x10x10 cm3) were immersed in 23% w/w NaCl solutions (control samples: 4ºC, 90 min; frozen samples: -15ºC, 180 min). Half of the frozen samples were immediately thawed at 4ºC. The other half was stored at -20ºC for 2 months and then was thawed at 4ºC (frozen-stored samples). Samples were stored at 4ºC and assayed at 1, 7, 14, 20, 27, 34, and 41 days. Rheological tests were carried out in oscillatory mode (parallel-plate geometry, diameter: 20 mm, gap: 1 mm, frequency: 1 Hz). Strain sweeps were run (0.001£g0£0.1) at 20, 40, and 60ºC, and temperature sweeps were run from 20 to 65ºC (1.33ºC min-1, g0=0.005). Similar crossover temperatures were observed after 20 days of ripening. The influence of temperature on complex viscosity was studied by an Arrhenius-type equation. Activation energy values of 15.9±0.4, 14.1±0.5 and 13.8±0.6 Kcal mol-1 were obtained at 41 days for control, frozen and frozen-stored samples, respectively. Although the immersion freezing of Mozzarella cheese affects some of the studied parameters, the differences observed between frozen and frozen-stored samples with control samples were small. Therefore, it was considered that the immersion freezing might be useful for the manufacture and commercialization of Mozzarella cheese.Fil: Ribero, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rubiolo, Amelia Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Zorrilla, Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Microstructure of Mozzarella cheese as affected by the immersion freezing in NaCl solutions and by the frozen storage

The freezing of Mozzarella cheese by immersion in NaCl solutions may be an innovative procedure for the dairy industry because it combines conveniently salting and freezing processes. The influence of this type of freezing method and of the frozen storage of samples on the microstructure of Mozzarella cheese was studied. Slabs (2 10 10 cm3) were immersed in 23% w/w NaCl solutions (control samples: 4 C, 90 min; frozen samples: 15 C, 180 min). Half of the frozen samples were immediately thawed at 4 C. The other half was stored at 20 C for 2 months and then was thawed at 4 C (frozen-stored samples). Samples were stored at 4 C and assayed at 1, 14 and 41 days. Although the immersion freezing of Mozzarella cheese affects its microstructure, only small differences were observed in the frozen-stored samples compared to control and frozen samples. Those differences consisted on less defined honey-comb appearance and the presence of small cracks at 41 days of ripening in the frozen-stored samples. Therefore, it was considered that the immersion freezing might be useful for the manufacture and commercialization of Mozzarella cheese.Fil: Ribero, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rubiolo, Amelia Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Zorrilla, Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Initial freezing point of Mozzarella cheese

The initial freezing point in unsalted fresh Mozzarella cheese was measured. The influence of the water-soluble solids on the freezing point depression of unsalted Mozzarella cheese was analyzed. Central temperature profiles and the initial freezing point of unsalted cylindrical cheese samples (1 cm radius; 3 cm height) were determined. A lyophilized aqueous extract of the soluble solids at pH 4.6 was obtained from the unsalted cheese. Initial freezing points of the solutions, prepared with a concentration of soluble solids similar to the one occluded in unsalted cheese matrix and different NaCl concentrations, were determined. Initial freezing points of the unsalted cheese were in the range of -1.2 to -2.4 ºC, while a value of -1.7 ± 0.1 0C was observed in the solution of soluble solids without NaCl. Moreover, the initial freezing points of the solutions of soluble solids and NaCl showed an additional depression of approximately -1.7 0C compared to the initial freezing point of NaCl solutions. Therefore, it was clearly shown that not only NaCl but also the other soluble solids present in the aqueous phase significantly contribute to the freezing point depression of Mozzarella cheese.Fil: Ribero, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Rubiolo, Amelia Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Zorrilla, Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; Argentin

Enhanced application of square wave voltammetry with glassy carbon electrode coupled to multivariate calibration tools for the determination of B6 and B12 vitamins in pharmaceutical preparations

Vitamins B6 (VB6) and B12 (VB12) were simultaneously determined in pharmaceutical preparations by using square wave voltametry (SWV) together with artificial neural networks (ANNs). Supporting electrolyte solution, pH and voltametric technique were optimised. The calibration set was built with several artificial samples containing both active ingredients and excipients. Deviations from linearity were observed for both analytes. It is probably due to interactions among the electro active components and competition by the electrode surface, fact that supports the use of ANNs. Recoveries when analysing a nine sample validation set, of 100.2 and 96.4 were calculated for VB6 and VB12, respectively. Commercial samples were analysed with reasonably good results considering the complexity of the mixture studied.Fil: Hernández, Silvia Raquel. Universidad Nacional del Litoral; ArgentinaFil: Ribero, Gustavo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Desarrollo Tecnológico para la Industria Química. Universidad Nacional del Litoral. Instituto de Desarrollo Tecnológico para la Industria Química; ArgentinaFil: Goicoechea, Hector Casimiro. Universidad Nacional del Litoral; Argentin

External Fruit Quality and Harvest Time of Low-Chill Peach and Nectarine Varieties at Santa Fe, Argentina

Background: We studied low chilling peach varieties recently introduced at the central area of Santa Fe, Argentina, to increase the range of options available to growers of warm-temperate areas. Objective: The aim of this study was to evaluate the external fruit quality and the harvest time of different low-chill peach and nectarine varieties in central Argentina. Results: The harvest period began on the last week of October and extended continuously until the end of December. Although the different varieties ripened in an adequate sequence throughout the season, the second week of November was a critical period in which six varieties reached maturity simultaneously. On the other hand, only a limited number of varieties ripened during the second and fourth weeks of December. Fruit size of peach but not of nectarine showed a positive and significant relationship with the length of the fruit development period. Three peach varieties (‘Flordastar’, ‘Rojo dos’ and ‘San Pedro 1633’) and four nectarines (‘Sunwright’, ‘Nectarine 24’, ‘Carolina’, and ‘Brasil’) produced small fruits (<100 g), which can affect their marketing. Red over-color on the skin was deficient, since only seven varieties developed 50% of red cover. Conclusion: The new varieties tested are suitable for extending the harvest period at the central area of Santa Fe, and will increase the range of options available to growers. However, before recommending its use, internal quality and fruit yield of these varieties should be evaluated for more years.Fil: Giovanelli, Carolina. Università di Padova; ItaliaFil: Bouzo, Carlos Alberto. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Ribero, Gustavo Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Castro, Damian Cesar. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Micheloud, Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; ArgentinaFil: Gariglio, Norberto Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentin

Novel topological-architectural parameters of root growth in Soybean (Glycine max (L.) Merrill) to determine the presence of soil mechanical impedance

Objectives: Mechanical impedance causes structural changes in roots. Nevertheless, little is known about the changes in soybean root systems grown under compacted soils (mechanical impedance). The aim of this work was to understand the morphological and topological-architectural changes occurred in plants root system of soybean grown under soil compaction. Methods/Analysis: Three experiments were carried out and three mechanical impedance levels were tested. Silt loam soil passed through a 2-mm-mesh sieve (Typic Argiudol Esperanza series) was used. Three soil compaction levels were determined: 1.1 g.cm-3, null mechanical resistance (NR); 1.3 g.cm-3, low mechanical resistance (LR); and 1.5 g.cm-3, corresponding to high mechanical resistance (HR). Three soil resistances were consequent determine: < 0.1 MPA, 0.5 MPa and 3.5 MPa, respectively. Morphological, geometrical and topological-architectural roots parameters were measured. Findings: Plants grown in HR conditions had a root system confined to the first centimeters of the ground and showed shorter total root length, less number of lateral roots, higher diameter and low specific length. Growth form of root systems was sensitive to soil mechanical impedance even at resistance levels lower than 1 MPa. As soil impedance increases, lateral root growth occurs via the principal root rather than via the secondary roots and there were higher numbers of lateral roots on the principal root in the area from the proximal zone to the stem base. Novelty/Improvement: The main differences among NR, LR and HR plants were due to changes in the characteristics of the root system rather than in the shoot system, particularly in the root growth zone. As a conclusion, the present research demonstrates that there are morphological parameters that can be used to determine if crops have been exposed to soil computation.Fil: Ramos, Julio Cesar. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Céccoli, Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Cs.Agrarias. Departamento de Biologia Vegetal; ArgentinaFil: Panigo, Elisa. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Dellaferrera, Ignacio Miguel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Moras, Gonzalo. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Vegetti, Abelardo Carlos. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Ribero, Gustavo Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Perreta, Mariel Gladis. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Cátedra de Morfología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentin

Relationships between copper content in orange leaves, bacterial biofilm formation and citrus canker disease control after different copper treatments

Citrus canker is caused by Xanthomonas citri subsp. citri (X. citri), a severe and wide-spread bacterial pathogen. Repeated copper sprays are part of integrated management systems applied in countries where canker is endemic. The objective of this research was to evaluate the effect of a low copper compound, copper sulphate pentahydrate, as soil applications and sprays, on canker intensity, in comparison with traditional application of copper oxychloride. Two independent trials were conducted in 2010 and 2011 in a canker endemic sweet orange orchard. Products were monthly applied during springs. Copper content in young leaves and fruits after each application was assessed through an atomic absorption spectrometer. In addition, the ability of treatments to interfere with bacterial biofilm formation was evaluated under controlled conditions. Soil application of copper sulphate pentahydrate did not reduce citrus canker incidence. In 2011, the pulverization of copper sulphate pentahydrate and copper oxychloride reduced the incidence of the disease compared with untreated trees. Notably, copper content in leaves sprayed with the first compound was significantly lower than in leaves treated with copper oxychloride. However, both treatments showed the same ability to avoid biofilm formation, the first step in establishment of canker disease. Consequently, the pulverization of copper sulphate pentahydrate, integrated with the monitoring of the phenological tree stages and the weather conditions, could constitute a useful tool for the management of citrus canker disease, of high importance to avoid the adverse environmental effects, the risk of phytotoxicity, and the development of copper resistant bacterial populations.Fil: Favaro, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Roeschlin, Roxana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Ribero, Gustavo Gabriel. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Maumary, Roxana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; Argentina. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; ArgentinaFil: Fernandez, Laura Noemí. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Lutz, Alejandra. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe; ArgentinaFil: Sillon, Margarita. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; ArgentinaFil: Rista, Luis Mario. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; ArgentinaFil: Marano, María Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Instituto de Biología Molecular y Celular de Rosario. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: Gariglio, Norberto Francisco. Universidad Nacional del Litoral. Facultad de Ciencias Agrarias. Departamento de Producción Vegetal; Argentin