Caking characteristics and sensory attributes of ramen soup powder evaluated using a low-resolution proton NMR technique

A low-resolution proton nuclear magnetic resonance (NMR) technique was used to characterize the quality of ramen soup powder during storage. The caking behavior of ramen soup powders was observed during 20 weeks of storage at different temperatures (30, 37, 45, and 55 °C) by monitoring changes in spin–spin relaxation times (T2) using a CPMG (Carr–Purcell–Meiboom–Gill) pulse sequence. Water in ramen soup powder was classified into two fractions based on two spin–spin relaxation times, T21 and T22, and their respective proton intensities, A1 and A2. Increases in T21 and T22 were observed during storage at 37, 45, and 55 °C, which indicated that the molecular mobility of water in ramen soup powder increased. The changes in A1 and A2 suggested that there was a redistribution of water from a lesser “bound” water state to more mobile state during storage. T21 and A1 were critical factors for explaining the caking characteristic of ramen soup powder during storage. Also, the results showed that sensory attributes of ramen soup powder deteriorated during storage, indicating that caking could accompany changes in organoleptic qualities and that these changes could be detected by monitoring changes in NMR parameters.