Spin-spin relaxation time determination of intermediate states in heterogeneous products from free induction decay NMR signals

For technical reasons, spin-spin relaxation times (T2) in the 50–600 μs range cannot be determined by a Carr-Purcell-Meiboom-Gill (CPMG) sequence. In complex heterogeneous compounds such as food products, these relaxation times correspond to liquid at the solid-liquid interface and/or an amorphous phase as well as possibly a “solid-like” state. We have developed a process of free induction decay nuclear magnetic resonance (FID NMR) signal treatment which allows the quantitative determination of T2∗ distributions corresponding to these states from low field NMR spectroscopy measurements. Thus, this kind of NMR spectrometry is a valuable alternative to differential scanning calorimetry (DSC) measurements since it can be used as a routine control method in industry.