The changes of active ingredients content, moisture status and texture characteristics during the moistening of Paeoniae Radix Alba were studied by low-field NMR and imaging(LF-NMR/MRI) and texture analyzer, so as to analyze the correlation between LF-NMR parameters, texture characteristics and active ingredient content of Paeoniae Radix Alba during the moistening at diffe-rent times. The results showed that MRI technology could directly, vividly and accurately characterize the degree of moistening and the process of water migration, and the degree of moistening was consistent with the judgment results of traditional experience. The characteristics of moisture migration and moisture phase state in the moistening process of Paeoniae Radix Alba were that the total water content increased and existed in the form of free water, with an increased moisture mobility. In the case of dampening, the total water content did not increase, but the more watery part of the medicinal material was distributed to the less watery part, with a reduced fluidity. Finally, the medicinal materials were moistened, which can be mutually verified with the MRI results. The free water content and the total water content of Paeoniae Radix Alba had extremely negative correlations with hardness, surface toughness, internal toughness, Paeoniflorin and albiflorin contents(P<0.01). It showed that the use of LF-NMR/MRI and texture analyzer could better characterize the moistening process. It provides data characterization for the scientific connotation of "less soaking and more moisturizing, and the drug is completely saturated with water", and the traditional experience of "observing the water head". The feasible and objective evaluation method was helpful to optimize the softening process parameters, scientifically standardize the operating specifications, define the scienti-fic connotation of traditional Chinese medicine softening, and promote the inheritance and innovation of traditional Chinese medicine processing.
Keywords: LF-NMR; Paeoniae Radix Alba; active ingredients content; moistening process; texture characteristics.