Optimization Of Solid Fermentation Of Cordyceps Militaris And Its Application In The Development Of Low GI Products

With the development of social economy and the improvement of people's living quality,there has been a dramatic change in the diet of the general public,from plant-based foods to animal-based foods.This change has brought many new health problems,diabetes was one of them.As the third most chronic non-communicable disease,diabetes has brought serious troubles to the general public.However,for most diabetic patients,regulating diet can achieve the purpose of controlling blood sugar,if combined with exercise can achieve an ideal therapeutic effect.Based on this,in order to provide food for diabetic and healthy people to control blood glucose and reduce the risk and harm of diabetes,this study uses solid fermentation of Cordyceps militaris to reduce the glycemic Index(GI)of grain medium,and uses the obtained fermentation bacteria to develop a low GI food to help control postprandial blood glucose.The specific research content is mainly divided into the following three parts:1.In order to obtain the fermentation product of C.militaris with lower GI value and high active substance content,shorten the production cycle and reduce the cost.the dominant strain of C.militaris for solid fermentation of rice substrate were screened with mycelial growth rate,expected glycemic index(eGI),contents of polysaccharide and cordycepin as screening indicators.The results showed that the content of rapidly digestible starch(RDS)in all the fungal substances fermented by strains of C.militaris(Shennongda,Wanxi,Yun and Quan)was decreased after,while the content of slowly digestible starch(SDS)and resistant starch(RS)decreased.Further digestion kinetics in vitro showed that the eGI value in fungal substance was significantly lower than that before fermentation(P<0.05).Then combined with the results of four indexes,strain Quan was determined as the best one for solid fermentation of rice.After 25 days fermentation,the eGI value of fermentation product decreased from 80.33(before fermentation)to 65.63,which reaching the level of medium GI value.The polysaccharide and cordycepin contents in fungal substance of Quan respectively were 5.29% and 5,185.98 mg/kg,which were higher than those in fruiting body.2.In order to further reduce the eGI value of fermentation product and increase the content of active substances,the expected Glycemic Index(eGI),and the contents of cordycepin and pinastatin were used as evaluation indexes,the medium formulation and culture time of solid fermentation were optimized by single factor and orthogonal design.The results showed that the optimal culture medium consisted of solid material and nutrient solution with an optimal solid-liquid ratio of 1?0.9.The solid material comprised70% main material(rice and oat with a mass ratio of 4?6),and 30% auxiliary material(soybean meal).Liquid complete medium containing 10 g/L of glycine were used as nutrient solution.The optimal incubation time was 25 ? for 18 days.The eGI value of fermentation product obtained under this culture condition decreased from 65.86 to 53.86,reaching the low GI level,and the contents of cordycepin and pinastatin were 12204.55mg/kg,and 1021.48 mg/kg,respectively.This study provided raw materials and basis for the development of low GI food by using the fermentation substances of C.militaris.3.In order to develop a low GI food for the adjunct treatment or prevention of diabetes,the fermented product of C.militaris obtained after optimization were used as raw materials and other raw materials were mixed to develop C.militaris noodles and C.militaris grain powder.The eGI value of C.militaris noodles was 58.63,close to the low eGI level,and the contents of cordycepin and pinastatin were 2685.21 mg/kg and 224.01mg/kg respectively.The eGI value of C.militaris mixed powder was 54.29,reaching the low level of eGI value,the content of cordycepin and pinastatin were 7932.66 mg/kg and612.89 mg/kg respectively.