1,720,986 research outputs found
Datos sobre un modelos de queso amargo para evaluar la actividad peptidolítica de fermentos lácticos
No full textDatos corresponden a un estudio sobre un modelos de queso amargo para evaluar la actividad peptidolítica de fermentos lácticosFil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Bergamini, Carina Viviana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin
Detección de la presencia de leche de vaca en leche de oveja mediante electroforesis
No full textLa leche de oveja se caracteriza por su elevado contenido de solidos totales, especialmente grasa y proteínas, cuyos valores oscilan alrededor de 4,15 y 5,15 respectivamente. Indudablemente que estos altos niveles en los componentes mayoritarios se ven reflejados en los rendimientos queseros. Tales ventajas, sumadas a la baja producción propia de la especie y a su disponibilidad estacional, hacen que la leche de oveja adquiera un valor de casi el triple de la leche bovina. Este contexto ha propiciado el desarrollo de ciertas prácticas fraudulentas, tales como la sustitución total o parcial de leche de oveja por leche bovina. A partir de esto ha surgido la necesidad de contar con técnicas analíticas que permitan a las autoridades competentes garantizar la autenticidad de aquellos productos en cuya identificación se explicita su fabricación con leche de oveja. En este trabajo se presenta un método para tal fin basado en la electoforesis en gel de poliacrilamida.Fil: Zalazar, Carlos Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin
Influence of residual milk-clotting enzyme and proteolysis on melting properties of soft cheese
Get PDFIn this work, we assessed the influence of coagulant residual activity and primary proteolysis on Cremoso Argentino cheese melting properties. For that purpose, we made Cremoso soft cheeses using different amounts of coagulant, and also obtained samples in which milk clotting enzyme was inactivated. The residual activity of coagulant correlated with primary proteolysis, especially in early stages of ripening. Caseins’ hydrolysis did not significantly impact on the melting ability of the cheeses, expressed as the area increase after heating samples under standardised conditions. Samples with similar proximate composition showed some changes in meltability; those seemed related to pH evolution during ripening.Fil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Alonso, María Jimena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin
Susceptibility of bovine whey proteins to the several proteolytic enzymes of industrial applications
No full textFil: Candioti, Mario César. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina.La incorporación de proteínas del suero lácteo (sueroproteínas) a diferentes alimentos, especialmente quesos, es una práctica frecuente que requiere conocer su respuesta frente a los sistemas enzimáticos existentes en el medio. Se estudió, mediante ensayos in Vitro, la susceptibilidad de las sueroproteínas (nativas, parcialmente desnaturalizadas y puras) a la acción de: pepsina porcina, pepsina bovina, renina bovina; coagulante de bovino adulto, coagulantes de origen microbiano, renina producida por fermentación y tres proteasas comerciales de origen bacteriano y fúngico. Se hicieron incubaciones a 37°C, durante 48 horas y pH del sustrato 5,4. Para la relación enzima/sustrato, se tomó como referencia el cuajo de bovino adulto, al triple de la concentración normalmente empleada en al elaboración de quesos, para obtener la mayor hidrólisis posible. Finalmente se realizó un ensayo caseario, elaborándose tres quesos cremosos: uno testigo, uno agregando el 4,5% de ricotta semimagra y otro ídem, más una proteasa.
Los resultados de los ensayos in vitro, evidenciaron una escasa actividad proteolítica de las enzimas coagulantes puras sobre las sueroproteínas nativas, dirigida principalmente hacia la alfa-lactoalbúmina. La reninas bovina y producida por fermentación, fueron prácticamente inactivas. Las proteasas comerciales exhibieron un nivel de hidrólisis comparable al de los coagulantes comerciales, atacando con perfiles muy diferentes tanto a la alfa-lactoalbúmina, como la beta-lactoglobulina. Parcialmente desnaturalizadas, las sueroproteínas revelaron importantes cambios tanto en la intensidad, como en los patrones de hidrólisis. El ensayo caseario, mostró que la actividad de la proteasa empleada frente a las sueroproteínas desnaturalizadas, también ocurre en el ambiente propio del queso.Addition of whey proteins to different foods, such as cheeses, is a common practice, needing an enlarge of the knowledge in relation to the behavior of the different enzymes present in the matrix against these proteins. The objective of this work was to study, by means of in vitro assays, the susceptibility of whey proteins (native, partially denatured and pure) to the action of several proteolytic enzymes: porcine pepsin, bovine pepsin, bovine chymosin, liquid coagulant from adult bovine, commercial rennets from microbiological sources, chymosin obtained by fermentation and three commercial proteases obtained from diverse microorganisms, used in food applications. Incubations were made at 37ºC, during 48 hours at pH 5.4. As a reference, a relation enzyme/substrate threefold of the concentration of liquid adult bovine rennet normally used cheese elaboration was selected in order to obtain the highest hydrolysis. Three soft cheeses were also made: a witness without addition and two experimental: one with 4.5% of semi-fat ricotta an another one with a protease.
The results of in vitro assays showed a very low proteolytic activity of milk-clotting enzymes on native whey proteins mainly for alpha-lactalbumin. Bovine and fermentation rennins had practically an identical behavior, producing a very slight hydrolysis. Commercial proteases, exhibited similar levels of proteolysis than commercial rennets, hydrolyzing with different profiles both alpha-lactalbumin and beta-lactogloblin. Partially denatured whey proteins showed hydrolysis profiles very different. From cheese-making experiences it was proved that denatured whey proteins can also be hydrolyzed in cheese matrix by the tested protease.Universidad Nacional del Litora
Susceptibility of bovine whey proteins to the several proteolytic enzymes of industrial applications
No full textFil: Candioti, Mario César. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina.La incorporación de proteínas del suero lácteo (sueroproteínas) a diferentes alimentos, especialmente quesos, es una práctica frecuente que requiere conocer su respuesta frente a los sistemas enzimáticos existentes en el medio. Se estudió, mediante ensayos in Vitro, la susceptibilidad de las sueroproteínas (nativas, parcialmente desnaturalizadas y puras) a la acción de: pepsina porcina, pepsina bovina, renina bovina; coagulante de bovino adulto, coagulantes de origen microbiano, renina producida por fermentación y tres proteasas comerciales de origen bacteriano y fúngico. Se hicieron incubaciones a 37°C, durante 48 horas y pH del sustrato 5,4. Para la relación enzima/sustrato, se tomó como referencia el cuajo de bovino adulto, al triple de la concentración normalmente empleada en al elaboración de quesos, para obtener la mayor hidrólisis posible. Finalmente se realizó un ensayo caseario, elaborándose tres quesos cremosos: uno testigo, uno agregando el 4,5% de ricotta semimagra y otro ídem, más una proteasa.
Los resultados de los ensayos in vitro, evidenciaron una escasa actividad proteolítica de las enzimas coagulantes puras sobre las sueroproteínas nativas, dirigida principalmente hacia la alfa-lactoalbúmina. La reninas bovina y producida por fermentación, fueron prácticamente inactivas. Las proteasas comerciales exhibieron un nivel de hidrólisis comparable al de los coagulantes comerciales, atacando con perfiles muy diferentes tanto a la alfa-lactoalbúmina, como la beta-lactoglobulina. Parcialmente desnaturalizadas, las sueroproteínas revelaron importantes cambios tanto en la intensidad, como en los patrones de hidrólisis. El ensayo caseario, mostró que la actividad de la proteasa empleada frente a las sueroproteínas desnaturalizadas, también ocurre en el ambiente propio del queso.Addition of whey proteins to different foods, such as cheeses, is a common practice, needing an enlarge of the knowledge in relation to the behavior of the different enzymes present in the matrix against these proteins. The objective of this work was to study, by means of in vitro assays, the susceptibility of whey proteins (native, partially denatured and pure) to the action of several proteolytic enzymes: porcine pepsin, bovine pepsin, bovine chymosin, liquid coagulant from adult bovine, commercial rennets from microbiological sources, chymosin obtained by fermentation and three commercial proteases obtained from diverse microorganisms, used in food applications. Incubations were made at 37ºC, during 48 hours at pH 5.4. As a reference, a relation enzyme/substrate threefold of the concentration of liquid adult bovine rennet normally used cheese elaboration was selected in order to obtain the highest hydrolysis. Three soft cheeses were also made: a witness without addition and two experimental: one with 4.5% of semi-fat ricotta an another one with a protease.
The results of in vitro assays showed a very low proteolytic activity of milk-clotting enzymes on native whey proteins mainly for alpha-lactalbumin. Bovine and fermentation rennins had practically an identical behavior, producing a very slight hydrolysis. Commercial proteases, exhibited similar levels of proteolysis than commercial rennets, hydrolyzing with different profiles both alpha-lactalbumin and beta-lactogloblin. Partially denatured whey proteins showed hydrolysis profiles very different. From cheese-making experiences it was proved that denatured whey proteins can also be hydrolyzed in cheese matrix by the tested protease.Universidad Nacional del Litora
Mini soft cheese as a simple model for biochemical studies on cheese-making and ripening
Get PDFA new miniature cheese model obtained under controlled microbiological conditions was proposed, characterized and tested for reproducibility. Optimal heat treatment of cheesemilk was defined, as well as maximal ripening time. Miniature cheeses were obtained with batch pasteurized milk (65 °C, 30 min) and ripened at 5 °C. Lactic and nonlactic microbial populations were monitored by plate counts. Proteolysis was assessed by nitrogen fractions, electrophoresis and liquid chromatography, and a sniffing test was applied to evaluate aroma. Coliform bacteria decreased during ripening but moulds and yeasts increased up to 104 cfu/g after 60 d, which defined the end of ripening period. Starter population remained constant during all ripening (109 cfu/g), while nonstarter lactic acid bacteria increased from ~102 to 104 cfu/g. Soluble nitrogen levels at pH 4.6, in trichloracetic acid (0.73 mol/l) and in phosphotungtic acid (0.009 mol/l) were 151, 67, and 10 g/1000 g of the total nitrogen, respectively, after 60 d of ripening, which are usual values for soft cheeses. Proteolytic patterns as measured by electrophoresis were also similar to those of standard cheeses, as well as the aroma of the products. Peptide profiles revealed that the areas of most peaks increased with ripening time. The proposed model showed to be suitable for the production of mini cheese specimens for laboratory testing of cultures and enzymes in similar conditions to their real environment in the food matrix.Fil: Milesi, Maria Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Salud y Ambiente del Litoral. Universidad Nacional del Litoral. Instituto de Salud y Ambiente del Litoral; ArgentinaFil: Candioti, Mario César. Universidad Nacional del Litoral; ArgentinaFil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin
Influence of residual milk-clotting enzyme on αs1 casein hydrolysis during ripening of Reggianito Argentino cheese
Get PDFMilk-clotting enzyme is considered largely denatured after the cooking step in hard cheeses. Nevertheless, typical hydrolysis products derived from rennet action on αs1-casein have been detected during the ripening of hard cheeses. The aim of the present work was to investigate the influence of residual milk-clotting enzyme on αs1-casein hydrolysis in Reggianito cheeses. For that purpose, we studied the influence of cooking temperature (45, 52, and 60°C) on milk-clotting enzyme residual activity and αs1-casein hydrolysis during ripening. Milk-clotting enzyme residual activity in cheeses was assessed using a chromatographic method, and the hydrolysis of αs1-casein was determined by electrophoresis and high performance liquid chromatography. Milk-clotting enzyme activity was very low or undetectable in 60°C- and 52°C-cooked cheeses at the beginning of the ripening, but it increased afterwards, particularly in 52°C-cooked cheeses. Cheese curds that were cooked at 45°C had higher initial milk clotting activity, but also in this case, there was a later increase. Hydrolysis of αs1-casein was detected early in cheeses made at 45°C, and later in those made at higher temperatures. The peptide αs1-I was not detected in 60°C-cooked cheeses. The results suggest that residual milk-clotting enzyme can contribute to proteolysis during ripening of hard cheeses, because it probably renatures partially after the cooking step. Consequently, the production of peptides derived from αs1-casein in hard cheeses may be at least, partially due to this proteolytic agent.Fil: Hynes, Erica Rut. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; ArgentinaFil: Aparo, Luciana. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Programa de Lactología Industrial; ArgentinaFil: Candioti, Mario César. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Lactología Industrial. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Lactología Industrial; Argentin
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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