Preparation And Activities Of Astragalus Membranaceus Yogurt And Anemarrhena Asphodeloides Yogurt

In this paper, Streptococcus thermophilus, Lactobacillus bulgaricus,Bifidobacterium adolescentis and Lactobacillus acidophilus were used as startercultures to prepare a novel Anemarrhena asphodeloides yogurt (AAY).Streptococcus thermophilus, Lactobacillus bulgaricus and Bifidobacteriumadolescentis were used as starter cultures to prepare a novel Astragalusmembranaceus yogurt (AMY). Furturemore, physicochemicl properities andhypoglycemic activity of the two yogurts also were investigated.The optimal conditions of AMY were explored by single-factor and Box-Behnkenexperimental design methods: the viable count ratio of S. thermophilus, L. bulgaricusand B. adolescentis of1:1:1, inoculation concentration of3.53%(v/v), maltitol of8.00%(w/w), A. membranaceus water extraction of15.25%(v/v), xylooligosaccharideof1.93%(w/w), fermentation temperature at43℃and fermentation time for5h. Underthis condition, the sensory score of AMY was94.4. During30days of refrigeratedstorage, titration acidity of the AMY was increased, but the numbers of there kindsof lactic acid bacteria were decreased; syneresis was increased firstly then descented,while water-holding power was at opposite; A. membranaceus total saponin content hadno obvious change. Compared with the control yogurt, hardness, smoothness, cohesiveforce and coefficient of viscosity of AMY increased significantly, and total content of freeamino acid increased dramatically. The result of rheological properties determinationsuggested that the storage modulus, loss modulus, and consistency index (κ, Pa sn) of AMYwere higher than the control yogurt, while flow behaviour index (n) decreasedsiginificantly. AMY showed more apparent shear thinning behavior, and has highviscosities and a better mouthfeel. We detected out twenty four and twenty flavourcomponents in AMY and control yogurt, respectively, mainly including alcohols,ketones, aldehydes, acids and a small amount of esters. Howerer,2-pentyl furanwas detected in AMY but not in control yogurt.The optimal fermentation conditions of AAY were as follows: the viable count ratioof S. thermophilus, L. bulgaricus, B. adolescentis and L. acidophilus of1:1:2:1,inoculation concentration5.29%(v/v), milk powder of12.00%(w/w), A. asphodeloideswater extraction11.04%(v/v), maltitol of10.64%(w/w), isomalto-oligosaccharide of1.20%(w/w), fermentation temperature of42℃and fermentation time of5.5h. Thesensory score score of AAY was94.3points, and the score of taste, texture and flavor werehigher than the control yogurt. During the storage, AAY’s titration acidity and syneresiswere increased, while pH value, water-holding power and the numbers of lacticacid bacteria were descreased. Compared with the control yogurt, hardness, smoothness,cohesive force and coefficient of viscosity of AMY were increased by8.4%,9.7%,10.8%and49.4%, respectively. Under the same oscillation strain, storage modulus (G’) andloss modulus (G") of AAY were higher than the control yogurt Consistency index (κ) ofAAY were higher than the control yogurt, while flow behaviour index (n) decreasedsiginificantly. The result suggested AAY had a better mouthfeel than the control yogurt.When the shear rate was less than101/s, AAY showed a more pronounced shear thinning.Twelve kinds of free amino acids were detected in AAY, including seven essentialamino-acids and the content of phenylalanine, lysine were significantly increased comparedwith the control yogurt. Twenty eight flavour components were detected out in AAY,mainly including ketones, aldehydes, alcohols and esters.The results of animal experiment showed AMY and AAY could increase the bodyweight of streptozotocin diabetic mice, and blood sugar levels of mice intaking AMY andAAY were reduced by24.56%and26.11%, respectively. Compared with the negativecontrol, the food intake, contents of insulin and total superoxide dismutase of mice in AMYand AAY groups were significantly increased, while the contents of malondialdehyde,blood urea nitrogen, creatinine, triglycerides, and total cholesterol and low-densitylipoprotein cholesterol were reduced by different degrees. The results indicated that AMYand AAY had good hypoglycemic activity and improvement on the complications (kidneydisease and hyperlipemia).