A rheological approach to the study of concentrated milk clotting |
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Authors: | Stefano Curcio Domenico Gabriele Vincenzo Giordano Vincenza Calabrò Bruno de Cindio Gabriele Iorio |
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Institution: | (1) Department of Chemical Engineering and Materials, University of Calabria I-87030 Arcavacata di Rende (CS), Italy e-mail: bruno.decindio@unical.it, IT |
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Abstract: | The aim of the present work is to analyze the complex phenomena involved in the concentrated milk clotting process in order
to define general criteria applicable to the design of a continuous coagulator. A full characterization of the rheological
properties of completely hydrolyzed milk as a function of two different parameters, i.e., the coagulator temperature and the
concentration degree of the milk, is presented. The dynamic evolution of loss, G′′, and storage, G′, moduli has been obtained
at different frequency values and for different concentration degrees during the clotting process. Time cure tests have been
performed on completely hydrolyzed milk samples showing that the rate of curing is very high and that the time for rheological
experiments is much too short for testing Winter's theory of gelation. To overcome this problem, the intersect of loss and
storage moduli was used for estimating the coagulation. Coagulation is faster when higher temperatures are used and the consistency
of the final curd is greater if a more concentrated milk is used. A tentative physical explanation based on the network theories
is presented. If an observation time far enough from the crossover point is chosen it can be seen that the curd strength estimated
at 40 °C is about 50 times higher than that one evaluated at 25 °C. Among the considered temperatures, a good processing value
was evaluated at 40 °C.
Received: 6 February 2000 Accepted: 24 October 2000 |
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Keywords: | Milk Coagulation Gel Rheology |
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