Spatial Investigation of the Non-frozen Water Distribution in Frozen Foods using NMR SPRITE

ABSTRACT: Nuclear magnetic resonance (NMR) was used to investigate the spatial distribution of the non-frozen water in foods during freezing and frozen storage. For samples such as beef, orange juice, and dough, their NMR responses were characterized and studied over temperature and during storage at subzero temperatures. The content of liquid-like components, such as unfrozen water, was measured in the temperature range between 20 and -40 °C. Ice formation led to a significant decrease of the amount of liquid-like components. This also was gradually diminished during storage, due to slow crystallization. Moreover, 1- and 2-dimensional images of the proton distributions in the frozen samples were obtained by single point ramped imaging with T₁ enhancement (SPRITE). The use of SPRITE to examine frozen foods allowed a spatial evaluation of liquid-like spins during freezing and storage.