Production Of Polysaccharide By Germinated Brown Rice Fermented With Cordyceps Sinensis And Technology Of Isolation And Purification

Cordyceps sinensis and germinated brown rice all contained high nutritional value, especially the functional active ingredients cordyceps polysaccharide and y-aminobutyric acid (GABA) respectively, which have become research focus. Fermentation using germinated brown rice which was rich of GABA and cordyceps sinensis was studied in this research; ingredients of fermentation product which was rich of cordyceps polysaccharide and GABA were researched; extraction, purification and properties as well as the antioxidant activity of the cordyceps polysaccharide was studied deeply. New ideas and theoretical guidance were provided for new functional food research and industrialization, respectively.The optimal process of gathering GABA by response surface optimization test was soaking temperature 34℃, soaking time 21h, germination temperature 33℃ and germination time 26h. Through this process, the GABA content reached 189.58 mg/100 g, which was 2.21 times the content of non-germinated brown rice. Therefore, effect of GABA enrichment is significant.The optimum conditions of producing cordyceps sinensis polysaccharide by solid state fermentation were as follows:1:3 of feed liquid ratio,1:0.5 of inoculum concentration, 28℃ of temperature,6 days of fermentation time. At optimal conditions, the yield of polysaccharide was 4.27%. The optimum conditions of producing cordyceps sinensis polysaccharide by liquid state fermentation were as follows:1:0.8 of inoculum concentration,28℃ of temperature,1:7 of feed liquid ratio,700mL /min of air flow speed, 7 days of fermentation time. The yield of polysaccharide was 6.93% at optimal conditions.The results showed that PPS was a kind of neutral sugar and soluble in water but insoluble in organic solvents, which did not contain starch, reducing sugar, uronic acid, polyphenols, amino acids and proteins. According to the SEM images, the morphological properties of PPS were observed as an aggregative state of unconsolidated fragments. The molecular weight of PPS was 26178Da and the pH value of PPS solution at 10 mg/mL was 6.8. The PPS showed strong thermal stability, which had two melting peak temperature (97.32℃.180.21℃) and high decomposition temperature (200℃), which was composed of glucose, mannose, and galactose with the molar ratios of 21.7,4.3,1.7. The main glycosidic bond of PPS was β-D-glucopyranoside. which suggested that the chemical bond of PPS’s back bone was β-D-glucan, and the branched chain was connected by a-1,6 chemical bond.The cordyceps sinensis polysaccharide PPS had good antioxidant activity, which probably was basis of antioxidant activity element in cordyceps sinensis polysaccharide.