NMR-STUDY OF WATER IN SOME STARCHES AND VEGETABLES

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Abstract
The paper contains a discussion of the possibilities and limitations of pulsed and wide-line NMR-experiments for the investigation of special problems in food science and technology. In starches two kinds of bound water can be observed. For potato starch the life times and the probabilities of occupation of molecules in these regions are discussed. The self-diffusion coefficient of the more mobile kind can be determined to be about 10-6 cm2/s for room temperature. For some starches an anisotropic mobility of the water molecules in this region can be detected by deuteron resonance. This resonance shows further characteristic differences at temperatures above the swelling point which can be used for studies of structural influences of technical processes, like the heat and moisture treatment. For the deuterated starches possibilities of studies of swelling and retrogradation phenomena are discussed. The experiments on starches are extended to beans, peas and lentils where rehydration and cooking processes are studied. For carrot tissue a self diffusion experiment is discussed for the investigation of processes going on in the course of cooking.