[Isothermal adsorption, desorptionand thermodynamic properties of Scutellaria baicalensis pieces].

To study the characteristics of adsorption and desorption of Scutellaria baicalensis pieces. On the basic thermodynamic theory, thestatic method was adopted to obtain S. baicalensis pieces' isothermal adsorption and desorption data at 25, 35, 45 ℃, with the water activity between 0.10 and 0.85. Eight moisture models were selected to fit the data and then evaluated to determine the thermodynamic properties of S. baicalensis pieces. The results show that, among the eight adsorption models, Peleg fit the best, in which absolutely-safe and the relatively-safe moisture contents of S. baicalensis pieces were around 9.22% and 13.51% respectively; the net equivalent heat adsorption and desorption and the differential entropy of S. baicalensis pieces were closely related to moisture content, and decrease within crease of water content; when drying the pieces, 12.0% of moisture content can be taken as the drying end; both of adsorption and desorption processes were driven by enthalpy and non-spontaneous. The study on S. baicalensis pieces' isothermal adsorption and desorption rules can help advance studies on adsorption and desorption rules of Chinese herbal pieces, and play a good guiding role in optimizing storage conditions and drying process of Chinese herbal pieces.

[Effect of air humidity on traditional Chinese medicine extract of spray drying process and prediction of its powder stability].

In order to solve the adhesion and the softening problems of traditional Chinese medicine extract during spray drying, a new method of adding dehumidified air into spray drying process was proposed, and the storage stability conditions of extract powder could be predicted. Kouyanqing extract was taken as model drug to investigate on the wet air (RH = 70%) and dry air conditions of spray drying. Under the dry air condition, the influence of the spray drying result with different air compression ratio and the spray-dried powder properties (extract powder recovery rate, adhesion percentage, water content, angle of repose, compression ratio, particle size and distribution) with 100, 110, 120, 130, 140 °C inlet temperature were studied. The hygroscopic investigation and Tg value with different moisture content of ideal powder were determined. The water activity-equilibrium moisture content (aw-EMC) and the equilibrium moisture content-Tg (EMC-Tg) relationships were fitted by GAB equation and Gordon-Taylor model respectively, and the state diagram of kouyanqing powder was obtained to guide the rational storage conditions. The study found that in the condition of dry air, the extract powder water content decreased with the increase of air compression ratio and the spray drying effect with air compression ratio of 100% was the best performance; in the condition of wet air, the extract powder with high water content and low yield, and the value were 4.26% and 16.73 °C, while, in the dry air condition the values were 2.43% and 24.86 °C with the same other instru- ment parameters. From the analysis of kouyanqing powder state diagram, in order to keep the stability, the critical water content of 3.42% and the critical water content of 0.188. As the water decreased Tg value of extract powder is the major problem of causing adhesion and softening during spray drying, it is meaningful to aid dehumidified air during the process.