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The application of high hydrostatic pressure (HHP) treatment has been proposed to reduce the ripening time of cheese via modifications in the enzymatic activities or the substrate reactivity. Investigations on the effect of HHP on cheese proteolysis have been undertaken with either encouraging results or little effect according to the treatment conditions and the type of cheese, but information concerning the effect of HHP on the ripening of hard cooked cheese is still lacking. In this report, we describe the effect of HHP treatment on Reggianito cheese proteolysis. For that purpose, 1-d-old miniature cheeses (5.5-cm diameter and 6-cm height) were treated at 100 or 400 MPa and 20°C for 5 or 10 min, and control cheeses in the trial were not pressurized. All cheeses were ripened at 12°C during 90 d. The HHP did not affect gross composition of the cheeses, but microbial load changed, especially because the starter culture count was significantly lower at the beginning of the ripening of the cheeses treated at 400 MPa than in controls and cheeses treated at 100 MPa. Cheeses treated at 400 MPa for 10 min had significantly higher plasmin activity than did the others; the residual coagulant activity was not affected by HHP. Proteolysis assessment showed that most severe treatments (400 MPa) also resulted in cheeses with increased breakdown of αS1- and β-CN. In addition, nitrogen content in soluble fractions was significantly higher in cheeses treated at 400 MPa, as well as soluble peptides and free AA production. Peptide profiles and individual and total content of free AA in 60-d-old treated cheese were as high as in fully ripened control cheeses (90 d). Holding time had an effect only on pH-4.6-soluble nitrogen fraction and plasmin activity; cheese treated for 10 min showed higher values than those treated for 5 min, at both levels of pressure assayed. We concluded that HHP treatments at 400 MPa applied 1 d after cheesemaking increased the rate of proteolysis, leading to an acceleration of the ripening process in Reggianito Argentino cheese, whereas 100-MPa treatments did not lead to significant changes. EEA Rafaela Fil: Costabel, Luciana Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina Fil: 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; Argentina Fil: Vaudagna, Sergio Ramon . Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto Tecnología de Alimentos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnica; Argentina Fil: Cuatrin, Alejandra. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina Fil: Audero, Gabriela Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela. Grupo Calidad de Leche y Agroindustria; Argentina 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; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química; Argentina

Reggianito is the most important variety among the Argentinean hard cheeses. During its ripening period several biochemical reactions of proteins and fat are responsible for its final sensory characteristics. The fat transformations, in a first step, produce free fatty acids (FFA). In the present work, the FFA profile from C6:0 to C18:2 during ripening was evaluated. Reggianito cheeses were produced with a “wild” whey starter and with selected strains of Lactobacillus helveticus isolated from natural whey. Information from FFA profiles was processed by Principal Component Analysis (PCA) and Discriminant Analysis (DA). Despite the fact that FFA levels grew continuously during ripening, no differences were found among cheeses produced with different starters. Sensory analyses did not show differences among the different cheeses produced. All cheeses were of satisfactory sensory quality. Results from this study are important for an increased knowledge of the ripening process of Reggianito cheese, considering the scarce information currently existing on this subject. At the same time, the substitution of a natural whey starter for a selected strain starter appears to be a possible advantage in order to improve and to standardize the quality of the cheese.El queso Reggianito es la variedad más importante dentro de los quesos duros fabricados en Argentina. Durante la maduración se producen innumerables reacciones bioquímicas sobre sus constituyentes, que conducen a definir las características sensoriales típicas de esta variedad de queso. Una de estas transformaciones involucra a la materia grasa originándose en una primera etapa ácidos grasos libres (AGL). En el presente trabajo se evaluó el perfil de AGL desde C6:0 hasta C18:2 a diferentes tiempos de maduración, en quesos Reggianito elaborados con suero fermento natural y con cepas seleccionadas de Lactobacillus helveticus. La información obtenida de los perfiles cromatográficos fue analizada por Análisis por Componentes Principales (ACP) y Análisis Discriminante (AD). Los niveles de los AGL aumentaron significativamente (p < 0,05) durante la maduración, sin embargo no se encontraron diferencias entre los quesos producidos con distintos fermentos. El análisis sensorial indicó que todos los quesos fueron similares y presentaron una calidad sensorial satisfactoria. Los resultados de este estudio además de contribuir al mejor conocimiento de la maduración del queso Reggianito, considerando la escasa información existente sobre la degradación de la materia grasa (lipólisis), realizan un significativo aporte para tratar de reemplazar los fermentos naturales por bacterias lácticas seleccionadas con todas las ventajas que ello significa para la estandarización y mejora de la calidad del producto.

Tesis para la obtención del Grado Académico de Doctora en Ciencias Biológicas, por la Universidad Nacional del Litoral, en 2015 El objetivo de este trabajo fue acelerar la maduración de queso Reggianito, mediante modificaciones de la tecnología tradicional. Las estrategias evaluadas fueron: i)incremento de la actividad de enzimas proteolíticas no microbianas, la enzima coagulante residual y la plasmina, a través de una modificación de la temperatura de cocción en presencia de dos coagulantes diferentes; y ii)aplicación de la tecnología de Altas Presiones Hidrostáticas (APH). En la primer experiencia, se estudiaron dos temperaturas de cocción: 50 y 56ºC, y dos tipos de enzimas coagulantes: bovina y de camello. Los resultados obtenidos muestran que un simple cambio en el proceso de elaboración de queso Reggianito como fue la reducción de la temperatura de cocción, fue efectivo para incrementar la actividad coagulante residual, con la consecuente aceleración de la proteólisis y peptidólisis de los quesos. En la segunda experiencia, se estudió el efecto del tratamiento con APH sobre la composición, el pH, el recuento microbiano, la proteólisis y peptidólisis, la textura y parámetros cromáticos de los quesos Reggianito, además de las características sensoriales. Para esto, quesos miniatura luego de la elaboración, fueron presurizados a 100 o 400MPa, a 20ºC por 5 o 10 min. En cada elaboración, se tuvieron quesos controles no tratados con APH. Esta experiencia mostró que el tratamiento a 400MPa fue efectivo para acelerar la maduración de queso Reggianito, a través del incremento en la proteólisis y peptidólisis. Además los quesos tratados a la mayor presión, mostraron una aceleración en el desarrollo de los atributos sensoriales de un queso maduro. The objective of this thesis was to accelerate the ripening of Reggianito cheese by means of modifications in traditional technology aimed at increasing proteolysis and peptidolysis. Two approaches were undertaken: i) increasing the activity of the no microbial proteolytic enzymes usually occurring in the cheese - residual coagulant enzyme and plasmin - through a modification of the curd scalding temperature in the presence of two different coagulants; and ii) application of high hydrostatic pressure (HHP). In the first experience, we tested two scalding temperature: 50 and 56ºC, and two type of coagulant enzyme, bovine or camel chymosin. The results obtained shown that a simple change in cheese making of Reggianito as decreasing the curd scalding temperature was effective to increase residual coagulant activity, with consequent acceleration of proteolysis and peptidolysis in cheeses. No advantage was obtained from replacement of bovine chymosin by camel chymosin. In the second experience, we studied the effect of the HHP treatment on gross composition, pH, microbial counts, proteolysis, peptidolysis, proteolytic activities, texture and chromatic parameters of Reggianito cheese, as well as its sensory profile. 1-day-old miniature cheeses were pressurized at 100 or 400 MPa and 20ºC for 5 or 10 min, while control cheeses in the trial were not pressurized. This experience provided evidence that HHP treatment at 400 MPa was effective to accelerate the ripening of Reggianito cheeses through increased proteolysis and peptidolysis. Cheeses treated at the higher pressure also showed an acceleration in the development of the sensory attributes of a ripened cheese. EEA Rafaela Fil: Costabel, Luciana Maria. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Rafaela; Argentina