Functional Activities Of Soybean Whey Fermented By Cordyceps Militaris SN-18

Soybean whey is the main by-product in the process of making traditional soybean products(especially tofu).Its output is huge in our country.In addition to a small part for the extraction of functional substance,the rest soybean whey are discharged as industrial waste-water.However,soybean whey is rich in nutrients and functional substances,which can not only be a waste of resources,but also be an ecological environment pollution.Cordyceps militaris is a kind of probiotics with rich nutritional value and edible safety,and Cordyceps militaris in liquid fermentation is similar to the natural Cordyceps sinensis.In this study,we choose Cordyceps militaris SN-18 as fermentation strain because it can grow well in soybean whey.This strain was used to liquid-state fermentation of soybean whey for improving the functional properties and encourage their utilization in the formulation of value-added functional foods.Finally,we can make full use of soybean whey.The main research contents and results as follow:1.Determination of soybean whey fermentation with Cordyceps militaris SN-18Terminal point of fermentation with Cordyceps militaris SN-18 was determined by measuring pH value,microbial biomass and sensory evaluation.The results showed that with the prolonging of fermentation time,pH value increased after a slight delay in the first day,mycelial biomass gradually increased until the sixth day.At the same time,appearance,taste and other sensory indicators of fermented soybean whey have reached the best state.Therefore we choose the 6th day as the terminal point of fermentation.2.Effects on the chemical and nutritional characteristics of soybean whey fermented with Cordyceps militaris SN-18The contents of chemical components,such as total crude protein,fat,carbohydrater and ash were analyzed.The contents of nutritional characteristics including reducing sugar,soluble protein,soybean oligosaccharide and the calcium enrichment ability of Cordyceps militaris were analyzed.The results showed that ash content increased,crude protein and total sugar content decreased significantly and crude fat content nearly unchanged.During the fermentation,the content of reducing sugar increased firstly and then decreased;Soluble protein and soybean oligosaccharides(Sucrose,raffinose and stachyose)were consumed for strain growth.In addition,the Cordyceps militaris SN-18 can also enrich the excessive calcium ions in the soybean whey,and the organic calcium is beneficial to human body absorption.3.Effects on the soybean isoflavone components and antioxidant capacity of soybean whey fermented with Cordyceps militaris SN-18Measurement of the total phenolic contents(TPC)and total flavonoids contents(TFC)and specific flavonoids composition of 80%ethanolic and water extracts from C.Militaris-fermented soybean whey and unfermented soybean whey.By using ABTS radical scavenging capacity,the ferric reducing antioxidant power,reducing power and ferrous ion chelating activity as the antioxidant capacity measurement model and the DNA damage by Fenton’s reagent to determinate the antioxidant capacity of soybean whey during fermentation.The results showed that 80%ethanol is more conducive to the extraction of total phenolics and total flavonoids in soybean whey,which showed a stronger antioxidant capacity and less cell damage.At the same time,the Cordyceps militaris SN-18 can transform Glycosides in the soybean whey into Aglycons with higher activity,so C.militaris-fermented soybean whey has a stronger antioxidant capacity and less cell damage.4.Effects of soybean whey fermented with Cordyceps militaris SN-18 on PC 12 cell injuries induced by H2O2Selection of 80%ethanolic extracts from C.militaris-fermented soybean whey(E-FSW)and unfermented soybean whey(E-USW),which had more flavonoids as materials.MTT assay revealed that both E-FSW and E-USW at the dose of 25-1000 μg/mL had no significant toxic effects on PC 12 cells,and exerted protective effects on PC 12 cells against 600 μM of H2O2-induced injury,furthermore,E-FSW protected more PC12 cells than E-USW from oxidative injury in a dose-dependent manner.Morphology of PC 12 cells observed by inverted phase contrast microscope showed that some PC 12 cells regained their inherent morphology when pretreated with E-FSW,that was a fibriform structure and a distinct boundary.Morphology of PC 12 cells observed by fluorescence microscope indicated that E-FSW could decrease more proportion of injuried cells than E-USW.E-FSW could retained the integrity of cell membrane,thus markedly attenuated the release of lactate dehydrogenase(LDH)compared with the impaired cells.Moreover,E-FSW could increase more activity of superoxide dismutase(SOD),catalase(CAT)and glutathione(GSH)contents of PC 12 cells than E-USW in a dose-dependent manner.Further experiments indicated that E-FSW could reduce more reactive oxygen species(ROS)level and apoptosis in PC 12 cells than E-USW.Finally,cell cycle analysis indicated that E-FSW could relieve G2 phase arrest induced by H2O2.All the results showed that E-FSW enriched of more active ingredient-Aglycons could protect PC 12 cells better than E-USW from H2O2-induced injury by reducing the apotosis.