Micro-Raman studies on the conformational behaviors of monosodium glutamate in dehydration process

The conformational behaviors of monosodium glutamate (MSG) in a dehydration process were studied by Micro-Raman spectroscopy in combination with Hartree–Fock calculations using 6-31+G* method. The dehydration process of the MSG droplet was performed by decreasing the ambient relative humidity (RH). The intensity ratio of the 935 cm−1 band to 884 cm−1 band (I935/I884) kept decreasing when RH decreased. By optimizing the geometries with different fixed dihedral angles, the downtrend of (I935/I884) is found to be due to the reduction of MSG molecular volume.