Study On Process Optimization And Quality Characteristics Of Dendrobium Candidum Wine Fermented By Lactic-acid Producing Bacillus Sp. And Saccharomyces Cerevisiae

Dendrobium candidum Wall ex Lindl.,known as dry stem of Dendrobium candidum,was a well-known traditional C hinese herb for maintainingtonicity of the stomach and enhancing immunity of body.In this atudy,we optimized the fermentation parameters of Dendrobium candidum wine by Bacillus sp.TQ-33（a lactic-acid producing bacteria）and Saccharomyces cerevisiae 171,and quality of the Dendrobium candidum wine fermented with and without lactic-acid producing bacteria.The major results and conclusions were listed as following:（1）According to the sensory scores,the starter mixtures of lactic-acid producing Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171 were optimized and mixed at the ratio of 1:10（v/v）.With the single factor experiement and response surface methodology,the optimal fermentation condtions were as follows:2%inoculum concentration,fermentation temperature 3℃,fermentation temperature 7 days.（2）Under these optimal fermentation conditions,the dynamic changes of the physical and chemical indicators in fermentation process of Dendrobium candidum wine by Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171 were further inverstigted.During the entire process,pH declined from initial 6.20 to 3.75,total total titratable acidity increased to 0.98%at the end of fermentation.Contents of alcohol and soluble solids showed rapidly rose and decreased trends on days 3⁵,the alcohol content increased to 5.20%Vo L but the soluble solids contents declined to 8%,at the end of fermentation,respectively.（3）Compared with the unfermented,lactic acid and tartaric acid were newly detected in the fermented Dendrobium candidum wine after fermentation with Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171,and the concentrations were 26.28 and 280.39 mg/L,respectively;the levels of citric acid and acetic acid significantly increased and the concentrations reached to 55.19 and16.78 mg/L,respectively;however,and malic acid concentration decreased from 53.01 to 33.86 mg/L.The delphinium-3-p-O-coumaric acyl glucoside,the dominant haematochrome of Dendrobium candidum plants,were also detected in the fermented wine.These results indicated that the red pigment could be matained in Dendrobium candidum wine after fermentation with Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171.In addition,after storage at 4℃for a period of 28 d,the contents of total total titratable acidity and alcohol increased slightly,however,the p H and anthocyanins content declined slightly,but no significantly changes were existed,which indicated that the fermented Dendrobium candidum wine after fermentation with Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171 possessed good storage stability.（4）The polysaccharide level in the fermented beverage only increased to 1.25 g/L after fetermation with Bacillus sp.TQ-33,however,the polysaccharide level n the fermented beverage only increased to 4.99 g/L after fetermation with Bacillus sp.TQ-33 and Saccharomyces cerevisiae 171.The weights of polysaccharide molecular,isolated from Dendrobium candidum plants,Dendrobium candidum plants after mixed fermentation,Dendrobium candidum wine after mixed fermentation,Dendrobium candidum plants after fermentation only with Bacillus sp.TQ-33 and Dendrobium candidum beverage after fermentation only with Bacillus sp.TQ-33,were 4.92×10⁵,5.03×10⁵,6.23×10⁴,5.21×10⁵,4.15×10⁵ KD,and the uronic acid contents of these polysaccharides were 206.98,253.72,231.86,170.16,333.10μg/mg,respectively.The iodine-potassium iodide test indicated that branches and long side chain might existed in the polysaccharides isolated from Dendrobium candidum wine after mixed fermentation and Dendrobium candidum beverage after fermentation only with Bacillus sp.TQ-3.Moreover,these five polysaccharides might possessed riple helical structure after chemical structure analysis using Congo red dye.（5）Furthermore,cell proliferation and TNF-αsecretion level of RAW264.7 cells of polysaccharideisolated fromDendrobium candidum wine after mixed fermentation is zsignificantly higher than another four kinds of polysaccharides,the cell proliferation rate and TNF-αsecretion level reached to 115.29%and 872.12 pg/mL in polysaccharides concentration of 25μg/mL.The IL-1βsecretion and NO promote levels reached maximal level in polysaccharides concentration of 200μg/mL.The polysaccharides isolated from Dendrobium candidum wine after mixed fermentation and Dendrobium candidum plants possessed the highest IL-1βsecretion and NO promote levels,and were 50.21pg/mL and20.31μmol/L,respectively.The phagocytic capacity of polysaccharide isolated from Dendrobium candidum plants after fermentation only with Bacillus sp.TQ-33and Dendrobium candidum wine after mixed fermentation were the highest and second highest,and reached to 259.21%and 252.63%,respectively.Overall,these results revealed that the content and immunomod ulatory activity of polysaccharide isolated from Dendrobium candidum wine could be obviously improved with the mixed fermentation of Bacillus sp.TQ-33 and Dendrobium candidum.