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Use of light scattering techniques to study the kinetics of precipitation of mineral acid casein from skim milk

Published online by Cambridge University Press:  01 June 2009

Mark S. Jablonka
Affiliation:
Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand
Peter A. Munro
Affiliation:
Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand
Geoffrey G. Duffy
Affiliation:
Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand

Summary

Two light scattering methods for monitoring the precipitation of casein from skim milk (9% w/w) with mineral acid are presented. Experiments were carried out at precipitation temperatures in the range 25–53 °C and precipitation pH values in the range 3·9–5·1. The initial stages of precipitation were explored using a light fibre optics system attached to a closed-loop acid/milk mixing system. The later stages of particle formation and growth were examined using a laser doppler anemometer attached to an open-pipe flow system. It was found that there was a lag initially, followed by a period of rapid particle growth. During a third phase a dynamic equilibrium between particle growth, break-up and shrinkage was established. A model for isoelectric casein precipitation based on these observations is proposed and discussed.

Type
Original articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1988

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References

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