The Fermentation,Activity Study And Product Development Of Selenium-enriched Hypsizygus Marmoreus Mycelium

Hypsizygus marmoreus is a kind of edible fungus with high development value and strong selenium enrichment capacity,but its fruiting body growth cycle is long and needs to consume large manpower and material resources.While its mycelium harvest cycle is short,substances with the same capacity as the fruiting body extract can be extracted.Therefore,it is of more research value to explore the selenium enrichment ability of Hypsizygus marmoreus mycelium,selenium-enriched fermentation conditions,and fermentation product activity.At present,the selenium-enriched fermentation method of edible mushroom mycelium is simple,and the research on active ingredients is only studied for intracellular or extracellular products.Moreover,the selenium-enriched fermentation technology of Hypsizygus marmoreus is not very mature.And there are few literatures on the extraction,purification and physiological activities of polysaccharides from Hypsizygus marmoreus mycelium powder.In this study,natural raw materials such as corn and soybeans were used as fermentation substrates,and selenium-enriched mycelium liquid grown from sodium selenite was used as an exogenous selenium additive.By comparing the effects of solid fermentation and liquid fermentation on the Hypsizygus marmoreus mycelium,the best fermentation mode was screened,and then the best fermentation conditions were optimized.Selenium-enriched polysaccharides were extracted from the fermentation product selenium-enriched mycelium powder,and compared with the polysaccharides extracted from Hypsizygus marmoreus mycelium powder and Hypsizygus marmoreus powder.The effects of selenium-enriched fermentation on the growth of Hypsizygus marmoreus mycelium,physicochemical properties and physiological activities selenium-enriched polysaccharides were investigated,so as to provide reference for the development of edible fungi fermentation technology and products.The main conclusions of this study are as follows:(1)The fermentation conditions of selenium-enriched Hypsizygus marmoreus mycelium were optimized successfully.Hypsizygus marmoreus mycelium could grow normally in the concentration range of 0-100 mg/L sodium selenite in solid culture and in the concentration range of 0-20 mg/L sodium selenite in liquid culture.The variable structure and morphology of Hypsizygus marmoreus mycelium cultured in 400 mg/L sodium selenite were observed.These results indicated that low concentrations of sodium selenite promoted mycelial growth of Hypsizygus marmoreus and higher concentrations inhibited mycelial growth.The yield of polysaccharide and the selenium content of polysaccharide were compared between the two fermentation methods,solid fermentation was determined as the best method.After optimization of the response surface experiment,the optimal process parameters of selenium-enriched solid fermentation were sodium selenite concentration of 29 mg/L,selenium-enriched mycelium liquid addition amount of 45%(v/w),inoculum amount of 15%(v/w).Under these fermentation conditions,The yield of polysaccharide and the selenium content of polysaccharide were 22.90±1.62% and 316.37±1.85 mg/kg,respectively.(2)Three kinds of polysaccharides were extracted,purified and characterized.Se-HMCP,HMCP and HCP were extracted from selenium-enriched Hypsizygus marmoreus mycelium powder,Hypsizygus marmoreus mycelium powder and Hypsizygus marmoreus powder.Se-HMP,HMP and HP were preliminarily purified.The crude polysaccharide yield of selenium-enriched Hypsizygus marmoreus mycelium powder,Hypsizygus marmoreus mycelium powder and Hypsizygus marmoreus powder were 22.90±1.62%,11.48±2.55% and 21.64±2.48%,respectively,indicating that selenium-enriched fermentation could promote the synthesis of polysaccharides from Hypsizygus marmoreus mycelium.Uv-visible spectroscopy showed that Se-HMP and HMP contained no or little protein and nucleic acid impurities,while some nucleic acid impurities remained in HP,which may affect the accuracy of subsequent determination of HP physiological activity.Uronic acid is a kind of bioactive polysaccharides.Se-HMP has the highest uronic acid content(15.60±1.46%),which is significantly higher than HMP and HP,indicating that selenium-enriched fermentation can improve the synthesis of uronic acid.At the same time,Se-HMP,which has the highest uronic acid content,has the lowest pH.The Congo red experiment showed that neither Se-HMP nor HMP had a triple helix structure,whereas HP had a triple helix structure.The organic selenium content of selenium-enriched Hypsizygus marmoreus mycelium powder was 446.71±6.45 mg/kg,and the organic selenium content of Se-HMCP was 344.21±1.37 mg/kg.Although the total selenium content,inorganic selenium content and organic selenium content of Se-HMP decreased,the degree of selenification of organic selenium was significantly higher than that of selenium-enriched mycelium powder and Se-HMPC,reaching96.88±0.29%.Infrared spectra showed that the three lines showed characteristic absorption peaks of polysaccharide.Compared with HMMP and HMP,the absorption peaks of Se-HMP appeared at 761.88cm-1 and 1024.07 cm-1,indicating that selenium was successfully combined with polysaccharide by Se=O bond and O-Se-O bond during se-enriched fermentation.SEM results showed that the selenium-enriched fermentation and purification process affected the micromorphology of polysaccharides.(3)Selenium-enriched polysaccharide has eminent antioxidant,immune activity and gastric protection.The antioxidant activity of Se-HMP,HMP and HP was compared with that of vitamin C.The antioxidant capacity of the three polysaccharides was lower than that of vitamin C,they still had higher antioxidant activity.Se-HMP was stronger than HMP in DPPH free radical scavenging activity and iron ion reducing antioxidant ability.The antioxidant stability results showed that storage at-20 ℃ could slow down the decline of antioxidant activity of each polysaccharide.The three polysaccharides could inhibit RAW264.7 polarization.In the concentration range of 0-1.00 mg/mL,Se-HMP increased RAW264.7 proliferation,and the effect was better than that of HMP and HP.In the phagocytic activity assay,HP promoted phagocytosis of neutral red in RAW264.7 within the concentration range,while low concentration of Se-HMP increased RAW264.7 phagocytic capacity,and high concentration of HMP increased its phagocytic capacity.All the three polysaccharides increased the levels of NO,TNF-α and IL-6 in the cell supernatant,HP significantly promoted the release of IL-6,while the contents of NO and TNF-α in the cell supernatant were similar to those in Se-HMP,but higher than those in HMP.All three polysaccharides increased the proliferation activity of GES-1,in the order of HP,Se-HMP and HMP.Conclusion:selenium-enriched fermentation enhanced antioxidant activity,RAW264.7 immune activity and GES-1 proliferative activity of the selenium-enriched polysaccharide to some extent.(4)Application of selenium-enriched mycelium powder in beverage.The optimum formula of selenium-enriched Hypsizygus marmoreus polysaccharide milk beverage obtained by optimization is: The added amount of polysaccharide solution is15%(v/w),the added amount of compound stabilizer is 0.05%,the added amount of milk powder is 3%(w/w),the added amount of stevia side is 0.1%(w/w),the added amount of citric acid is 0.02%(w/w),the added amount of potassium sorbate is 0.1%(w/w),and refill with drinking water to 100%.The beverage has a sweet smell,unique flavor and good stability.The beverage had good hydroxyl radical scavenging activity and DPPH radical scavenging activity.The physical and chemical indexes of the beverage showed that the soluble solid content of the beverage was ≥15%,and the heavy metal lead and total arsenic were not detected.