Influencia del contenido graso y de otras variables sobre la capacidad de fusión del queso Cremoso Argentino

The influence of the fat content, pH, the ripening degree and the incorporation of whey proteins, by two different methods, on the meltability of Cremoso Argentino cheese was examined. Different experimental cheeses were made at pilot plant scale and their meltabilities were determined by a modified Schreiber test. Ripening degree and fat content showed a good correlation with the meltability. Though, cheeses with incorporation of whey proteins showed poor meltability, despite their yields increased. No correlation was found between pH and meltability inside the pH working range studied.En el presente trabajo se estudió la influencia del contenido de materia grasa, pH, grado de maduración e incorporación de proteínas de suero mediante dos vías diferentes sobre la capacidad de fusión del queso Cremoso Argentino. Utilizando una técnica modificada del test de Schreiber se analizó la capacidad de fusión de distintos quesos experimentales elaborados a escala piloto. El contenido graso y el grado de maduración afectaron positivamente la capacidad de fusión. La incorporación de proteínas de suero produjo mayores rendimientos pero la capacidad de fusión se vio fuertemente disminuida. No se observó una influencia clara del pH dentro de los límites estudiado

Characterisation of Proteolysis Profile of Argentinean Sheep Cheeses Made by Two Different Production Methods

U radu su proučeni profili proteolize u argentinskom ovčjem siru napravljenim dvjema metodama proizvodnje kako bi se dobile tipične i definirane karakteristike. Proizvedeni su sirevi s mikrobnom kulturom Streptococcus thermophilus (S-sirevi) i sirevi s miješanom mikrobnom kulturom Streptococcus thermophilus i Lactobacillus bulgaricus (L-sirevi). Sirevi su dozrijevali na 12oC i 80% relativne vlažnosti kroz 180 dana i uzorci su uzimani tijekom tog vremenskog razdoblja. Rezultati pokazuju određene sličnosti ali i razlike, posebice u pH vrijednosti, dok je senzorska analiza pokazala bitne razlike između te dvije vrsta sireva. S-sirevi imaju niži stupanj proteolize i blaži okus, što ih čini prikladnim za konzumaciju nakon kratkog vremena dozrijevanja. L-sirevi imaju viši stupanj proteolize, te puno izraženija senzorska svojstva, što ih čini prikladnim za konzumaciju nakon duljeg vremena dozrijevanja.In this work the proteolysis profile of Argentinean sheep cheeses made by two production methods were studied in order to develop products with typical and defined features. Cheeses with a starter of Streptococcus thermophilus, (S-cheeses) and cheeses with a mixed starter of Streptococcus thermophilus and Lactobacillus bulgaricus, (L-cheeses) were manufactured. The cheeses were ripened at 12oC and 80% relative humidity for 180 days and samples were taken throughout this period. Results show similarities but also some differences, especially in pH value, while sensory evaluation indicated important differences between the two types of cheeses. S-cheeses had a low proteolysis and soft flavor, making them appropriate for consumption after a short ripening time. L-cheeses had a higher proteolysis level and more intense sensory characteristics, making them appropriate for consumption after a longer ripening time

Leuconostoc citreum MB1 as biocontrol agent of Listeria monocytogenes in milk

Cell-free supernatant from Leuconostoc citreum MB1 revealed specific antilisterial activity. Preliminary studies demonstrated the proteinaceous, heat-stable, bacteriocin-like trait of the antimicrobial components present in the supernatant. Determination of the genes encoding bacteriocins by PCR and DNA sequencing led to amplification products highly homologous with leucocin A (found in diverse Leuconostoc species) and UviB (found in Leuc. citreum KM20) sequences. Additionally, antimicrobial activity of cell-free supernatant from Leuc. citreum MB1 was revealed by an inhibition halo of the SDS-PAGE gel subjected to a direct detection using Listeria monocytogenes as indicator strain. Different assays were carried out to assess the capacity of Leuc. citreum MB1 to control List. monocytogenes growth: (i) inactivation kinetics of the pathogen by antilisterial compounds present in concentrated cell-free supernatant from Leuc. citreum MB1, (ii) evaluation of optimal Leuc. citreum MB1 initial concentration to obtain maximum List. monocytogenes ATCC 15313 inhibition, and (iii) biocontrol of List. monocytogenes ATCC 15313 with Leuc. citreum MB1 during growth in milk at refrigeration temperature. According to our results, it is unquestionable that at least one bacteriocin is active in Leuc. citreum MB1, since important antilisterial activity was verified either in its cell-free supernatant or in co-culture experiments. Co-culture tests showed that*107 CFU/ml Leuc. citreum MB1 was the optimal initial concentration to obtain maximum pathogen inhibition. Moreover, Leuc. citreum MB1 was able to delay List. monocytogenes growth at refrigerated temperature.Fil: Pujato, Silvina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Quiberoni, Andrea del Lujan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Candioti, Mario C.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Reinheimer, Jorge Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; ArgentinaFil: Guglielmotti, Daniela Marta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe. Instituto de Lactologia Industrial; Argentin