Proton relaxation of waxy and non-waxy rice by low field nuclear magnetic resonance (LF-NMR) to their glassy and rubbery states

The proton relaxation of waxy and non-waxy rice was investigated using low field nuclear magnetic resonance (LF-NMR). The relaxation showed 3 types of protons from their relaxation times as strongly-bound (T2b), moderately-bound (T21) and weakly-bound (T22). These relaxation times were analyzed as a function of temperature. The strongly-bound proton showed three characteristics of critical temperatures. The second critical temperature (i.e. when relaxation time increased after a plateau region) was observed as close to the DSC glass transition. Considering relaxation time as a function of temperature, one maximum peak was observed in the case of T2b and T21, whereas T21 showed an additional minimum peak. The relaxation time T22 did not show any peak, however non-waxy rice showed a minimum peak while it increased after a plateau region in the case of waxy rice. The characteristic relaxations were relatively similar in the cases of waxy and non-waxy rice, while both rice varieties showed similar diffraction angle (2θ) with different intensities as measured by X-ray diffraction (XRD).