Extraction Of Dendrobium Officinale Polysaccharides And Application In Yoghurt

Dendrobium officinale Kimura et Migo is a perennial epiphytic herb, its name is because of its iron green epidermis, and it is the best kind of dendrobii; it has hold the reputation of “gold in medicine” for a long time since the the ancient times, and it is called the “Life-saving diantheral” among the people.It mainly distributes in the eastern Zhejiang Province, Sichuan, southeast Yunnan, western Fujian, southwester Anhui, northwester Guangxi. Dendrobium officinale as a valuable Chinese herb has lots of pharmacology effect,such as spleen and nourishing the stomach, nourishing yin and tonifying the kidney, embellish lung cough and stimulate saliva, prolong life, and so on.The dendrobium officinale is treated as the raw material to research the extraction technology of dendrobium officinale polysaccharides. With ascorbic acid(hereinafter abbreviated as Vc) as the contrast, the antioxidant activity of dendrobium officinale polysaccharides was studied. At the same time, proliferation effect on the Bifidobacterium of dendrobium officinale polysaccharides had been studied. Then, the dendrobium officinale polysaccharides is applied to yogurt to develop a healthcare beverage. Through the experimental study, the conclusions are as follows:(1) water extraction and alcohol precipitation was used for extraction of d-endrobium polysaccharides. Based on the single factor experiments, designed a trial of three factors and three levels. It had shown that the test program by the response surface optimization analysis combined with the actual test conditi-on. According to Box-Behnken design principle, the mathematical model of de-ndrobium officinale polysaccharides extraction rate was obtained based on data of extraction temperature, extraction time and PH. The equation of the model is Y=13.31+0.058A-0.020B-0.065C-0.075AB+0.045AC+0.035BC-0.30A2-0.27B2-0.31C2. The optimum conditions were extraction temperature is 81℃, extraction time is 88 minutes, PH value is 6.0, ratio of material to water is l:25, and e-xtraction times is 2. Under such situations, polysaccharides yield can be up to13.31mg/ml,and the polysaccharide content was 26.76%;(2) dendrobium officinale polysaccharides has a certain reduction ability of free radicals.In the polysaccharides concentration ranging from 0.2 to 0.4mg/g, reducing power increased with the increasing of polysaccharides concentrations. Dendrobium officinale polysaccharides also has a certain ability to remove ?OH and DPPH. The IC50(half inhibition rate) of removing ?OH was as many 64 times as Vc, and the IC50 of removing DPPH was about 80 times, these co-nclusions showed that dendrobium officinale polysaccharides has a weak ability of removing ?OH and DPPH.(3) The dendrobium officinale polysaccharides was added as an additive agent to the yoghurt. Through orthogonal test, the best ingredients formula was obtained as follows: 0.8% dendrobium officinale polysaccharides, 65% fresh milk, 5.5% white sugar; and the optimum fermented process was 2.4% inoculum concentration, 40 ℃fermented temperature while 4.8h fermented time.The final product has a colour of milk white, beautiful flavor, moderate sweet and sour, delicate taste, and rich flavour.