Starch-water, gluten-water, and flour-water model systems as well as straight-dough bread were investigated with (1)H NMR relaxometry using free induction decay and Carr-Purcell-Meiboom-Gill pulse sequences. Depending on the degree of interaction between polymers and water, different proton populations could be distinguished. The starch protons in the starch-water model gain mobility owing to amylopectin crystal melting, granule swelling, and amylose leaching, whereas water protons lose mobility due to increased interaction with starch polymers. Heating of the gluten-water sample induces no pronounced changes in proton distributions. Heating changes the proton distributions of the flour-water and starch-water models in a similar way, implying that the changes are primarily attributable to starch gelatinization. Proton distributions of the heated flour-water model system and those of fresh bread crumb are very similar. This allows identifying the different proton populations in bread on the basis of the results from the model systems.

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The potential of Nuclear Magnetic Resonance (NMR) and Magnetic Resonance Imaging (MRI) for non‐invasively monitoring the subcellular and intercellular redistribution of water in cellular tissue during drying and freezing processes is assessed and it is concluded that despite exciting advances in NMR micro‐imaging and NMR microscopy, nonspatially resolved NMR relaxation and diffusion techniques still provide the best probes of subcellular water compartmentation in tissue. The power of the NMR relaxation technique is illustrated by using the changes in the distribution of NMR water proton transverse relaxation times to monitor the subcellular compartmentation of water and ice during the drying and freezing of parenchyma apple tissue. The NMR drying data are analysed with a numerical model of the cell and show that mild air‐drying in a fluidized bed results in loss of water from the vacuolar compartment, but not from the cytoplasm or cell wall regions. The loss of vacuolar water is associated with overall shrinkage of the cell and only a slight increase in air space. During freezing the vacuolar compartment is found to be the first to freeze, with the cytoplasmic and cell wall compartments only freezing at much lower temperatures. Freeze‐drying apple tissue gives much lower water contents than fluidized bed drying, but the NMR data confirms that it destroys membrane integrity and causes cell wall collapse.

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The major features of N.M.R. transverse water proton relaxation in solutions of native bovine serum albumin can be quantitatively interpreted in terms of fast chemical exchange between water and protein protons. Transverse proton relaxation dispersions are observed as a function of CPMG pulse spacing and spectrometer frequency and are shown to be consistent with the fast exchange of water with NH and OH protons of the amino acid side chains in the protein. The mean first order exchange rate is about 5 x 103s -1. Although there is evidence that proteins influence the state of the water around them (the so called 'bound' water concept) the results obtained suggest that this influences the proton relaxation in a minor way compared to the potent effect of the chemical exchange mechanism.

The penetration theory of interfacial mass transfer was used to model flavor release from liquid emulsions. The model was used to predict the rates of release and partitioning properties of two volatiles, one hydrophilic (diacetyl) and the other hydrophobic (heptan-2-one), as a function of the oil volume fraction. In general the initial rates of release were faster for emulsions of lower oil content, whereas the equilibrium concentrations depended on the nature of the flavor compound and the volume fraction of oil in the emulsion. Experimental in vitro results suggested that the rate limiting step for flavor release was the resistance to mass transport across the emulsion-gas interface.