Research On Fast Drying Technology Of American Ginseng

American ginseng is the root of the Panax quinquefolium of which is Araliaceaeplant, the most American ginseng products on the market are drying original Americanginseng currently. It starts produce into this kind in our country in 1975, through thedevelopment of nearly 30 years, it has already become a certain scale up to now. Ourcountry is the third large production country of American ginseng just behind the UnitedStates and Canada Currently. Along with the exaltation of the living conditions, thedemand of the American ginseng products is increasing faster, it has already reached thehead of the world currently. But the development of the dry processing technology ofAmerican ginseng is lagged comparatively, such as the dry time is too long, the energycost is too much and the quality of drying products is not very good. This study is basedon Hot-air drying, Freeze drying, Microwave drying, adopt two kinds of these dry methodcombined to carry on the experimental research of the American ginseng. Selected therepresentative index, adopted the fuzzy synthetic evolution to educe the optimizedparameter of combined drying, reached the purpose of fast drying.The main contents and conclusions are as follows:①Based on practical drying process of American ginseng, through the analyticalcalculation, designs a American ginseng drying house which has an ability to drying 2tevery time, and carry on the analysis of airflow spread and heat transferred inside of theAmerican ginseng drying house, attained the related drying parameter of the production.Apply the theory of similarity, take geometry scales as 1:10 to downsize the Americanginseng drying house, attained related technique parameter of the American ginsengdrying box: size of inside of the drying box is 0.72m×0.38m×0.34m, air quantity is 30.23m3/h, the difference in temperature between hot source and inside of drying box is 8℃,the difference in temperature between hot source and air is 16℃;Ideal state: thetemperature inside of the drying box is 40℃, the temperature of the air is 32℃, thetemperature of the hot source is 48℃;Actual state: the temperature inside of the dryingbox is 27.04℃, the temperature of the air is 13.52℃.②A merican ginseng is carried on Hot-air drying, Freeze drying, Microwave dryingrespectively, getting the moisture content data variety by drying time. Drew the moisturecontent curve diagram variety by drying time, according to the moisture content curvediagram, analyzed the regulation of moisture content changes during the Americanginseng drying time, and divided the dry process of American ginseng into three stage:the fast drying stage, middle constant drying stage, and the slow drying stage.③Carried on moisture content curve-fit with experimental data, and established themathematical model of American ginseng variety moisture content by drying time,attained the equation as followed:Hot-air drying: 9.95670.05520.093XY = +e?Freeze drying: 7.73474.0325.832XY = +e?Microwave drying: Y = 77. 112?0.352X+5.891×10?4 X2?3.561×10?7X3④D iscussed the reasons of green-skin and red-skin phenomenon occurred, and putforward the preventive method. The methods that keep the green-skin phenomenon fromappear are: Heated the drying box before drying American ginseng, increase the removehumid times, avoid use when American ginseng are washed and brushed with metals toolcontainer, adopts the wood system or bamboo systems as drying frame and drying netduring American ginseng drying. The method that keep red-skin phenomenon fromappear is control the drying temperature especially during the ending-time of Americanginseng drying, the temperature shouldn't be higher than 32℃ generally. The dryingprocess of American ginseng influence by drying temperature and humidity to ginseng isprominently, increasing the temperature grades and the humidity steps grades, to enlargethe drying power, enhance the drying speed.⑤S elected the appearance quality, moisture content, ash content, totalquinquenoside content, ginsenoside Rb1, amount of bacterium, amount of mildew andamount of coliform as experimental index of drying American ginseng products.According to the nation standard and domestic and international related information toanalysis each experimental index by qualitative and quantitative. Selected the total drytime, total drying energy cost, total quinquenoside content, moisture content and theappearance quality as evaluated index, establish the system of evaluated index and fuzzysynthetic evolution model to adjudicate the products of drying American ginseng.⑥Adopted Freeze and Hot-air combined, Freeze and Microwave combined, Hot-airand Microwave combined to dry American ginseng respectively. Designed the optimizedAmerican ginseng drying experiment, apply fuzzy synthetic evolution attained optimizedparameter of above three combined methods, then chose the best optimized parameter offast American ginseng drying, that is Freeze and Hot-air combined: freeze time is 2h,freeze temperature is -20℃, the pressure of drying box is 66 Pa, the temperature of heatedboard is 30℃, the drying method break point moisture content is30%, the temperature ofhot-air is 35℃, the velocity of hot-air is 1.5m/s.