Tesis (Ingeniero Agroindustrial) -- UACh. Departamento de Ingeniería Agroindustrial, 2005

Bibliografía : hojas 62-66

La leche cruda bovina constituye un buen medio de cultivo para numerosa microfiora, tanto banal como nociva. Sin embargo, en la leche existen inhibidores naturales, que le proporcionan cierta resistencia transitoria contra el deterioro; uno de ellos es la enzima lactoperoxidasa. Tal enzima actúa con dos co-sustratos: el tiocianato y el peróxido de hidrógeno; ambos tambien estan presentes normalmente en la leche, formando el sistema lactoperoxidasa (SLP). En esta investigación se evaluó el efecto del SLP de un kit comercial(Stabilak) sobre la calidad sensorial y fisicoquimica de un queso fresco elaborado con leche conservada por este método. Se efectuaron 5 tratamientos a la leche de queseria: leche cruda sin conservador (tratamiento 1), leche con Stabilak(tratamiento 2), leche cruda conservada a 4°℃ (tratamiento 3), leche con Stabilak y luego pasteurizada(tratamiento 4), y leche a 4°C y después pasteurizada (tratamiento 5). Los quesos experimentales, solamente mostraron diferencias estadísticamente significativas en humedad, no en proteina y grasa. Fisicoquimicamente, se halló diferencia en la evolución de pH y en actividad acuosa (aw). Sensorialmente, también se encontraron diferencias significativas entre los tratamientos; el queso procedente de leche con Stabilak y luego pasteurizada fue el mas preferido; el menos aceptado fue el testigo. La investigación confirmó el efecto conservador transitorio de la leche cruda tratada por el SLP comercial; sin embargo, se detectó la conveniencia de pasteurizar la leche tratada. De otra manera habria objeciones sensoriales en el producto

The bovine raw milk constitutes a good culture media for a wide number of microfiora, so much banal as injurious. However, in the milk exist natural inhibitors, that provides certain transitory resistance to him against the deterioration; one of them is the lactoperoxidase enzyme. Such enzyme acts with two co-substrates: the tiocianate and the hydrogen peroxide, both also usually present in the milk, forming the lactoperoxidase system (SLP). In this research was evaluated the effect of the SLP of a commercial kit (Stabilak) on the sensory quality and physicochemical of a fresh cheese, elaborated with milk conserved by this method. Five treatments were made on cheese dairy milk: raw milk without conservative (treatment 1), milk with Stabilak (treatment 2), raw milk conserved at 4°℃ (treatment 3), milk with Stabilak and then pasteurized (treatment 4) and milk at 4°℃ and later pasteurized (treatment 5). The experimental cheeses, only showed significative statistically differences in water content,not in protein and fat in the physicochemical analysis, were found difference in the pH evolution and water activity (aw). Sensorially also were found significative differences between the treatments, the cheese elaborated of milk with Stabilak and then pasteurized, had the higher preference; the fewer accepted were for the control (treatment 1). The research confirmed the transitory conservative effect of the raw milk treated by the commercial SLP; however, the convenience was detected of pasteurizing the treated milk. Otherwise there would have sensory objections in the product