ABSTRACT
ObjectiveThe hygroscopic properties of Mume Flos decoction pieces were studied from the perspectives of macroscopic［water activity（Aw）］ and microscopic（water molecular mobility）， which provided a theoretical basis for the determination of the safe storage moisture content. MethodAdsorption isotherm of Mume Flos decoction pieces was obtained by static weighing method， and seven common hygroscopic models were fitted and estimated. The best model was selected according to the principle that determination coefficient（R2） was closer to 1， residual sum of squares（RSS） was closer to 0 and Akaike information criterion（AIC） was smaller. According to the optimal model， the absolute and relative safe moisture contents of Mume Flos decoction pieces at 25， 35， 45 ℃ was calculated. Low-field nuclear magnetic resonance（LF-NMR） was used to measure the water molecular mobility in the hygroscopic process of Mume Flos decoction pieces. ResultThe best model to describe the adsorption isotherm of Mume Flos decoction pieces was the Peleg model. According to the model expression， the absolute safe moisture contents of Mume Flos decoction pieces at 25， 35， 45 ℃ were 9.59%， 7.96% and 7.68%， and the relative safe moisture contents were 13.05%， 11.99%， 11.77%， respectively. Mume Flos decoction pieces all contained two water states during the process of hygroscopic absorption at different temperatures， namely bound water T21 and free water T22. During the process of hygroscopic absorption， bound water had the largest increase in peak area. The sum of peak areas of the bound water and free water had a good linear relationship with the moisture contents， and the R2 were 0.959 9， 0.911 8 and 0.974 7 at 25， 35， 45 ℃， respectively. When Aw<0.57， T21 did not change， and the water molecular mobility remained unchanged. When Aw>0.57， T21 showed an increasing trend， and the water molecular mobility increased. The moisture contents of Mume Flos decoction pieces were 8.44%， 6.81% and 6.25% when the water molecular mobility increased at 25， 35， 45 ℃， respectively. ConclusionCombined with the theory of water activity and water molecular mobility， 6.25% is recommended as the safe storage moisture content of Mume Flos decoction pieces， this study can provide reference for determining the safe storage moisture content of other decoction pieces.
ABSTRACT
Mume Flos is a traditional Chinese medicinal material，with the effects of soothing the liver，resolving phlegm and dispelling stagnation. It was mainly used to treat globus hystericus，liver and stomach pain，loss of appetite，dizziness and scrofula. Mume Flos is native to China，with a long history of cultivation and application and complex and diverse varieties. There are hundreds varieties of Mume Flos，including fruiting Mei and flowering Mei. However，there was no ancient literature on which color of Mume Flos is the best traditional Chinese medicinal material among those with different colors，as well as relevant study report on the correlation between medicinal Mume Flos group and plant systematics. In order to define the origin，the author conducted the textual research on the changes in the origin，quality and producing areas of the Mume Flos in the past dynasties. According to the findings， traditional medicinal Mume Flos were mainly green calyx Mume Flos and white Mume Flos，and derived from flowering Mei of the true Mume branch. Among them， green calyx Mume Flos belonged to the green calyx group， while medicinal white Mume Flos belonged to the albo-plena group and the single-lobe group. The producing area of Mume Flos was first recorded in Sheng Nong's Herbal Classic，where now in southern Shaanxi province. After the Song dynasty，due to climate，social and economic factors，the producing areas of Mume Flos had continued to move southward from Shaanxi province to the Yangtze River and Dongting Lake basins. Till the Ming and Qing dynasties，the distribution of Mume Flos was also reported in Guangdong province and Hainan province. In modern times，due to the comprehensive impact of natural climate conditions and urbanization，the producing areas of medicinal Mume Flos had gradually changed from Sichuan province，Jiangsu province and Zhejiang province to southern Anhui province at present. In this paper，the textual research is conducted to define the origin and systematically summarize the changes in the producing areas of Mume Flos，so as to provide reference for defining the origin of Mume Flos and the groups of medicinal Mume Flos and making further development and utilization of resources.