PROTON LOW-FIELD NMR MEASUREMENTS ON CRACKERS

We have shown that the signal obtained for crackers (3.5% water content) by low resolution NMR method using the CPMG sequence, described the relaxation of the protons of fat. For water content up to 7.1% the water signal is not seen by a CPMG sequence, the water has therefore a very short spin-spin relaxation time (T2 < 0.5 ms). However, that water modifies the mobility of protons of fat at solid-liquid interfaces. Protons exchangeable by deuterium affect neither the relaxation time of the short component (about 1 ms), nor its intensity. Between 7.1% and 14.8%, the water had a spin-spin relaxation time of about 1 msec and its signal was added to the short component of the fat. Thus, low resolution NMR could be used to follow the crystallization of fat in such samples after cooking.