Research Of Dendrobium Nobile Lindl Drying

Medicinal Dendrobium nobile（Dendrobium nobile Lindl） stems. The main active ingredient is a polysaccharide, alkaloids, sesquiterpene glycosides and aromatic compounds（phenolic acids, Bibenzyls, phenanthrene compound etc）. Fresh stems contain large amounts of water and nutrients, so it is easy to microbial growth. Its dense skin, the moisture inside the stems so difficult to evaporate; when the moisture content decreases, wrinkled badly, the remaining water is more difficult to escape. Thus Dendrobium nobile fresh stems difficult dried or drying, drying time is long, low production efficiency, the active ingredient content is affected by drying method. In Chishui, Hejiang and other main origin, currently Dendrobium nobile drying method is mainly natural drying or drying, in the case of not cutting the stems, natural drying time often required for several weeks（subject to weather）, and bake 80 ℃ also need for 2 to 3 days or even longer.Therefore, how to quickly and effectively dried Dendrobium nobile, shorten the drying time, prevent spoilage, keeping medicinal ingredients, reduce the impact of drying on active ingredient content as much as possible is a serious problem to be solved.The main content of this paper is to Dendrobium nobile cut into about 0.5 cm sections,respectively summer exposure bake（60℃） and vacuum freeze, drying process analysis of quality changes, calculated moisture ratio and drying rate, dried draw curve established drying kinetics model; and compare the impact of different drying methods on Dendrobium nobile polysaccharides, total alkaloids, sesquiterpene glycosides and total aromatic compound content. Test results are as follows:（1） Dendrobium nobile drying process, dry method and drying method belong to slow down the drying process, and mainly for the rapid drying of the first stage. Pre-dried in a short time,the drying rate decreases with the decrease of moisture content, rapid decrease of water than,and then entered a slow drying process; drying method to dry more than the dry method equilibrium. Moisture effective diffusivity were 1.0210×10^-9 m²/s、4.4760×10^-9 m²/s. drying activation energy is about 46.42 k J/mol. dried method and drying method are in line with Two term model（double exponential function model）. Dried regression equation MR =0.1151exp（-0.0980t） + 0.8849exp（-0.8937t）; drying regression equation MR =0.0116exp（-0.0503t） + 0.9903exp（-1.9961t）.Of about 0.5 cm of Dendrobium nobile, the water content was 3.7125 dry, wet basis moisture content was 0.7878. Two term is calculated by the model, to achieve "Chinese Pharmacopoeia" moisture（wet basis） ≤12% of requirement, or make it wet basis moisture≤10% or ≤5%, the time required to dry law 11.66 h, 13.75 h, 21.37 h or more; drying method was 1.82 h, 1.97 h or 2.76 h above（calculated to be dried to the same moisture content of 5%to 12%, the time required for drying method is only dried law 12.92 % to 15.61%）.（2） Dry process: 1Polysaccharide content（P/%） and drying time（t/h） substantially linear change（by linear regression can be obtained: P = 0.03821 t + 1.1418,R2 = 0.97601）, showed stable polysaccharide content increase. 2The total alkaloid content（P/%） and the drying time（t/h） substantially linear change（by linear regression can be obtained: P =- 0.00705 t +0.85503;R2 = 0.97944）, expressed as the total alkaloid content is slowly reduced reduced to0.664%（24h） after, the content is almost unchanged. 3 Reducing total sesquiterpene glycoside content pre short time, later with the extension of the overall drying time increased gradually.（4）Aromatic compound by HPLC-UV analysis, the peak area with the extension of the analysis time was gradually decline.Drying process: 1a rapid increase in the polysaccharide content of 0 8 h; 8 h after the rate of increase has been slowing（linear regression can be obtained by the polynomial: P =-0.00477t2+ 0.20221 t + 1.0977,R2= 0.99839）. 2The total alkaloid content decreased rapidly early; reduced to 0.654%（8h）, reduce the total alkaloid content rate slowed, stabilized（linear regression can be obtained by the polynomial:P =- 0.0573ln（t） + 0.79106;R2= 0.97255）.3 Total sesquiterpene glycoside content overall with the extension of the drying time increased gradually.（4）Aromatic compounds by HPLC-UV analysis, the peak area in a short time pre-increase, after the extension of time dependent analysis showed a gradual decline.（3） Dendrobium nobile three kinds of drying method drying process:（1） Polysaccharide content increased with prolonged drying time increased gradually, and the result is a polysaccharide content of dried drying method > vacuum freeze-drying method> dry method > fresh stem.（2） Total sesquiterpene glycoside content overall with the extension of the drying time increased gradually（initial dried in the reduction, then gradually increase）, and the result is a total drying sesquiterpene glycoside content of drying method > vacuum freeze-drying method > dry method > fresh stems.（3） Although the peak area of aromatic compounds with prolonged analysis showed a gradual downward trend（increase in initial drying, then gradually decrease）, but tends to balance easily. Analyzed by HPLC-UV with different drying methods. From the change in the overall point of view, the impact of Dendrobium nobile aromatic compounds, the smallest vacuum freeze-drying, drying changed greatly. The main material from the point of view changes, changes in minimum drying, dried great changes. And the result is dried aromatic compounds bake main peak area dry > vacuum freeze-drying method > dry method, thewhole peak area and peak area above the stem and fresh.（4） Only the total alkaloid content increased with prolonged drying time was gradually decline, and three kinds of drying method drying results vary less total alkaloids content were less than the total alkaloid content of fresh stems.Considering drying long, drying costs and major material trends and degree in full broken,the drying method is more suitable for Dendrobium nobile drying. Not only can achieve Dendrobium nobile quick-drying, and valid for Dendrobium nobile ingredient adverse effects is small. Recommended drying drying time 8h appropriate at this Dendrobium nobile polysaccharide content of 2.48% and a total alkaloid content of 0.654%, the total sesquiterpene glycoside content of 8.82%, primary aromatic compound peak area close to the main stem of fresh peak area（t R of 43.5min）.（4） Times the initial establishment of a total of Dendrobium nobile sesquiterpene glycoside content estimation method. Because Dendrobium nobile of glycosides mainly sesquiterpene glycoside total; if measured Dendrobium nobile ingredient content of glycosides to estimate the total times Dendrobium nobile sesquiterpene glycoside content. The drying process of Dendrobium nobile sample were carefully placed in the bottom of the bucket cutting filter paper, placed in Soxhlet apparatus and add 100 m L ethanol soaked overnight, in another round-bottomed flask, add ethanol 100 m L Soxhlet 2h. Discarded powder, again carefully extract was added 5m L of concentrated hydrochloric acid, Common reflux for 1h. Precise amount of the extract 1.0m L in a test tube and add 5m L of distilled water, 5m L chloroform and extracted with a separatory funnel, and the supernatant as the sample solution. Precision drawing respectively the sample solution 1.0m L different drying method drying process prepared by adding 50g/L phenol solution 1.0m L, careful addition of concentrated sulfuric acid after mixing 5.0m L, mixing, boiling water bath boil 2min, taken out after cooling to room temperature, using a spectrophotometer at 485 nm Department to reagent blank solution as reference, measured with a 1cm cuvette absorbance value. According to another sample solution preparation process, we can calculate the glucose content of the sample, in terms of total glycosides content（glucose mass of the total ingredients glycosides 45.78%）. To estimate the total sesquiterpene glycoside content（by dry mass sample being measured Gt conversion）.