Objective

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Modern scientific methods and techniques were used to scientifically characterize the traditional softening process of Corydalis Rhizoma， so as to clarify the scientificity and rationality of the traditional process， and provide reference for inheriting the processing methods and experience of traditional Chinese medicine.

Method

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Low-field nuclear magnetic resonance imaging （LF-NMR/MRI） was used to characterize the water types and distribution in the softening process of Corydalis Rhizoma. Samples during the softening process was cut into thick slices and its section was observed by stereoscopic microscope. High performance liquid chromatography （HPLC） was employed to determine the content change of tetrahydropalmatine during the softening process with the mobile phase of methanol-0.1% phosphoric acid solution （60∶40， triethylamine regulated to pH 6.5） and detection wavelength at 280 nm. The determination method of softening endpoint of Corydalis Rhizoma was simulated by texture analyzer （hand pinch method）， and the softening degree of the finished products was determined after optimizing the relevant parameters.

Result

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LF-NMR/MRI showed that the water could penetrate through the core and distribute evenly in Corydalis Rhizoma softened by Zhangbang method. The water first entered into the medicinal material from the epidermis and stem marks in the soaking stage as the form of free water， and then penetrated into the inner core to achieve redistribution in the moistening stage. Under stereoscopic microscope， it was observed that Corydalis Rhizoma softened by the Zhangbang method could be sliced well， but the core bursting slices were easy to appear if the softening time was not enough， and the softening of samples was caused by the keratine-like powder after absorbing water. HPLC measurement showed that the loss of tetrahydropalmatine in the softening method was small， its content decreased about 5% in the soaking process， and its content was almost unchanged during the moistening process. The softening degree of Corydalis Rhizoma could be quantified by the texture analyzer， and the optimum parameters were 2 mm·s

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of speed before test， test speed and speed after test， 20 g of the trigger force， 20% of compression degree. The compressive force of the qualified softened Corydalis Rhizoma was 12.75-15.69 N with the relative standard deviation （RSD） of 6.8%.

Conclusion

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Modern scientific methods and techniques can characterize the scientificity and rationality of the traditional processing methods， and confirm that the Zhangbang softening method has the advantages of high efficiency， convenience and small loss of index components. The texture analyzer can simulate the softening endpoint judgment method （hand pinch method）， and realize the goal from subjective experience judgment to objective technology quantification， which has a good demonstration role for the modern inheritance of traditional processing technology.