Computerized Viscometric Method for Studying Rennet Coaguluation of Milk

Abstract

A viscometer (Rheomat‐30) was computerised by connecting a microcomputer (Apple II plus) through the interface: analog/digital converter (MID 1612M1). The maximal speed of the viscometer's signal readings was up to 20 records per second. This equipment was used to follow the apparent viscosity changes during the rennet coaguluation of milk. An equation describing the evolution of the viscosity as a function of time has been drawn. It seems to be sufficient to know the initial and maximal viscosity level and the time coordinates of two points: maximum and 0.6 of the viscosity amplitude, to be able to reproduce the viscosity versus time curve.

Characterization of rennet coagulation of milk concentrated by vacuum condensing and ultrafiltration

“…Each of these methods measure distinct properties, destructively or non-destructively, during coagulation by using respective principles. Though the viscometric methods do not give the same results as the nondestructive rheological methods because of lack of consideration of syneresis, such methods have been suggested to complement quite well to the studies on rennet coagulation of milk retentates obtained by concentrating milk (Korolczuk and Maubois 1987).…”

Comparative studies on the gelling properties of cardosins extracted from Cynara cardunculus and chymosin on cow's skim milk

“…Although determination of the ability of enzymes to effect milk coagulation is important, determination of the physical evolution of the gel is not of less importance; hence, studies on the structure and mechanical properties of milk gels have been carried out using viscometers (Scott-Blair & Oosthuizen, 1961;Kopelman & Cogan, 1976;Korolczuk & Maubois, 1987) and penetrometers (Steinholt, 1973). The Formagraph, originally designed to perform assays with the flour of cereals, was also adapted to record coagulation properties of cheese-milk (McMahon & Brown, 1982), although its measurements are somewhat empirical.…”

Qualité fromagère des laits de vache en fonction des régimes à base d'herbe

“…Le temps de coagulation a été mesuré par la méthode de Berridge (Collin et al, 1977) et l'analyse rhéologique de la coagulation a été réalisée à l'aide d'un viscosimètre rotatif Rhéo-mat 30 (Korolczuk et Maubois, 1987). Cette technique permet de décomposer l'évolution de la viscosité du lait emprésuré en fonction du temps en 2 phases importantes qui permettent une bonne discrimination des différents laits selon leur comportement à partir de l'emprésu-rage ( Fig.…”

“…L'évolution de la viscosité ainsi mesurée suit une courbe correspondant au modèle de Scott Blair (Korolczuk et Maubois, 1987). Pour l'ensemble de nos échantillons (n = 32), la vitesse de raffermissement du coagulum est liée négativement (P < 0,01) à la durée de la phase primaire (r = -0,70), et plus encore au temps de coagulation (r = -0,88).…”