Characterisation of the water-holding capacity of fresh cheese samples by means of low resolution nuclear magnetic resonance

New process steps in the production of fresh cheese were introduced and varied in order to reduce the undesirable phenomenon of syneresis without adding milk-foreign additives. Native and modified whey protein concentrates (WPC) with approx. 12% protein were used as ingredients in the production of fresh cheese spreads. During production the fresh cheese samples were submitted to an extra flow-induced mechanical stress. The aim of the present study is to detect changes of the water-holding capacity of different treated fresh cheese by means of the non-destructive low resolution nuclear magnetic resonance (LR NMR). Furthermore, a newly developed measuring method based on NMR, the so-called wash-out-test, was implemented in order to simulate syneresis of fresh cheese. The obtained data were correlated with the results of the viscosity and the firmness of the samples. Syneresis data were determined by decanting experiments as a function of the storage duration. The present study shows that the shearing procedure during processing has an influence on the viscosity of the final product, its firmness and the syneresis behaviour of the fresh cheese samples. The main result is that good syneresis properties seem to be correlated with a softer mechanical consistency of the products. The presented data indicate that NMR measurements and, especially, wash-out-tests are useful techniques to characterise the water-holding capacity (WHC) and the structure of differently treated fresh cheese samples. Based on this knowledge concerning the microscopic and macroscopic material behaviour, it is possible to improve the production processing and the final, consumer-relevant properties of fresh cheese products. (C) 2004 Elsevier Ltd. All rights reserved.