Enzyme-assisted Preparation Of Dendrobium Officinale Powder And Utilization Of Its Residue

Dendrobium officinale Kimura et Migo is a kind of rare Chinese herbal medicine,which belongs to the homologous plant of medicine and food.Traditional Chinese medicine believes that it has the effects of tonifying middle qi,invigorating stomach and producing fluid,nourishing Yin and clearing heat.Modern scientific studies have shown that Dendrobium officinale contains many functional active ingredients,which have the effects of lowering blood sugar,improving immunity,protecting liver and stomach.At present,Dendrobium officinale has been large-scale planted in our country,the production increases year by year.However,the processing method of Dendrobium officinale is still backward,and the products are single.Except for a small amount of fresh food,most of them are made into dry products,with low utilization rate and product added value.Therefore,it is imperative to improve the utilization rate of Dendrobium officinale and develop edible Dendrobium officinale products.In this work,we investigated the production process of instant Dendrobium officinale powder through enzymatic hydrolysis and spray drying to solve the problem of large viscosity and poor impulsivity of Dendrobium officinale products.And the content of antioxidant components and antioxidant activity of Dendrobium officinale powder in different stages of simulated gastrointestinal digestion,and the mechanism of its protective effect of digestion products on oxidative damage of liver cells were studied.Meanwhile,in order to realize the comprehensive utilization of Dendrobium officinale,the by-product of powder preparation process of Dendrobium officinale-Dendrobium officinale residue,was used to extract its dietary fiber.The main research contents and results are as follows:To improve the utilization of Dendrobium officinale,cellulase(10000 U/g),neutral protease(50 U/mg)and xylanase(100 U/mg)were selected as enzyme preparations for extracting Dendrobium officinale juice,and the enzymatic hydrolysis process was optimized by orthogonal test and response surface test.The optimal enzymolysis parameters were cellulase concentration of 0.24%,neutral protease concentration of 0.18%,xylanase concentration of0.24%,enzymolysis time of 3.2 h,enzymolysis p H of 5.46,enzymolysis temperature of 52℃.The juice yield and polysaccharide yield of Dendrobium officinale juice were the highest,which were 63.18%and 3.64%(fresh weight),respectively,and 46.05%and 49.79%higher than the control group.By comparing the physicochemical properties of Dendrobium officinale juice with and without enzyme-assisted extraction,it was found that the clarification,total soluble solid content,color index,total phenol content,total anthocyanin content,amino acid content and antioxidant activity(DPPH·,·OH and ABTS~+·clearance rate)of Dendrobium officinale juice were significant increased after enzymatic hydrolysis,while the viscosity,total flavonoid content and soluble protein content of the juice were decreased.By comparing the effects of different amounts of maltodextrin,acacia,sodium carboxymethyl cellulose and whey protein on powdering efficiency and powder quality of spray dried enzymatic Dendrobium officinale juice,principal component analysis was used to score the physicochemical properties of Dendrobium officinale powder,and the optimal carrier formula was selected.Results showed that Dendrobium officinale powder had the highest comprehensive score with the addition of 40%maltodextrin.The contents of total phenols and flavonoids and the antioxidant activities of Dendrobium officinale powder during digestion were evaluated by simulated gastrointestinal digestion in vitro.Compared with the undigested components(total phenols content 2.37 mg/g,total flavonoids content 217.38μg/g),the contents of total phenols and total flavonoids did not change significantly after simulated gastrointestinal digestion.The DPPH·,·OH and ABTS~+·antioxidant tests showed that the antioxidant activity of the simulated intestinal digestion increased by 5.78%,8.16%,and 4.29%compared to the undigested components,respectively.The results indicated that spray drying Dendrobium officinale powder had high stability in gastrointestinal tract.By establishing a model of acrylamide(ACR)induced oxidative damage in Hep G2 liver cells and exploring the protective effect of Dendrobium officinale powder digestion products on oxidative damage in Hep G2 cells.The use of 8 mmol/L ACR cause oxidative damage to Hep G2 cells(the cell survival rate was 48.32%),while the composition of Dendrobium officinale powder after intestinal digestion(1 mg/m L)can significantly inhibit the cytotoxicity induced by ACR(the cell survival rate was 76.23%).The analysis of its mechanism showed that Dendrobium officinale powder can significantly reduce the production of reactive oxygen free radicals in hepatocytes,protect against nuclear damage,and restore mitochondrial membrane potential,cellular glutathione levels,antioxidant enzymes such as superoxide dismutase and catalase activities,thereby protecting cells from oxidative damage.The microstructure,physicochemical properties and adsorption properties of residues(DOR)and total dietary fibers(DORF)from the preparation of Dendrobium officinale powder were compared.Fourier transform infrared spectroscopy showed that the functional groups of DOR and DORF were similar,and enzymatic hydrolysis enhanced the polysaccharides absorption peak of DORF.X-ray diffraction confirmed that the crystallinity of DORF prepared by enzymatic method was lower.Thermogravimetric analysis showed that DOR had higher thermal stability.Scanning electron microscopy observed that DORF was a loose and more porous surface structure.DORF exhibits higher water and oil binding capacity,water swelling capacity,glucose diffusion delay index,and glucose,cholesterol,bile acid salts,and nitrite adsorption capacity than DOR,while DOR had better cation exchange capacity.