NMR State Diagram Concept

ABSTRACT:  This article introduces a new concept, the NMR (nuclear magnetic resonance) state diagram, in the context of food shelf-life stability as affected by the molecular mobility of the food matrix. Our literature review shows that some shelf-life–related changes cannot be explained or predicted by the current a _w and glass transition temperature concepts. This article presents the theoretical principles and some experimental evidence of the NMR state diagram concept that could be complementary to the a _w and glass transition concepts. An NMR state diagram is a curve of NMR relaxation time versus temperature. Some of the curve features were found to correlate highly to the physiochemical states and changes of food polymers, for example, caking, stickiness, and firming. The potential applications of this concept in quality and safety of food products, especially dry and intermediate moist foods, may include ingredients screening, prediction of physiochemical changes, chemical degradation, and microbiological activity. The goal concept of this article is to provoke more in-depth studies to analyze the relationships among NMR relaxation, molecular mobility, and stability of foods.