Effects Of Different Corn Meal Addition On The Fermentation Parameters Of Fresh-potato

This study was conducted to analyze the changes of the fermentation indexes before and after conventional solid fermentation of different fresh-potato:corn meal ratio diet,and the optimal adding amount of corn meal was also determined.The test was divide into 5 treatments: 40% corn meal content(P6C4),30% corn meal content(P7C3),20% corn meal content(P8C2),10% corn meal content(P9C1)and without corn meal treatment(P10C0).Then the diets were fermented at 20 to 25?conditions after lactic acid bacteria(1.8×1011 cfu/g),yeast(5×109 cfu/g)and bacillus subtilis(1011 cfu/g)inoculation.Results showed that the fermentation pH index showed significantly quadratic linear decrease with the fermentation time(P<0.05),and the second-order coefficient a and the first-order coefficient b of pH fitting equation in(P6C4,P7C3 and P8C2 was significantly higher than that of P9C1 and P10C0(P<0.05).There was no significant difference among treatments on constant term c(P>0.05),and the pH of all treatments tended to be stable at 6day of fermentation.Other index including CP,NH3-N,lactic acid,acetic acid,propionic acid and butyric acid increased significantly along with fermentation time(P <0.05),however,DM,OM,starch and reducing sugar decreased significantly along with fermentation time(P<0.05).Dry matter recovery(DMR),organic matter recovery(OMR)and CP improvement of P8C2 treatment were higher than that of other treatments,and the P8C2 was the fastest ttreatment which reached the stable state.Average pH of whole process of all the treatments was increased linearly with the decreasing of cornflour addition(P<0.05).While average DM,OM,starch,reducing sugar,lactic acid,acetic acid,propanoic acid and butyric acid of whole fermentation process were reduced linearly with decreased of corn–flour addition(P<0.05).Pearson analysis showed that pH was positively correlated with DM,OM,starch,reducing sugar(P<0.05),and pH was negatively correlated with CP,lactic acid,acetic acid,propanoic acid and butyric acid(P<0.05).CP was positively correlated with NH3-N,lactic acid,acetic acid,propanoic acid and butyric acid(P<0.05),and it was negatively correlated with starch and reducing sugar(P<0.05).NH3-N was positively correlated with lactic acid,acetic acid,propanoic acid and butyric acid(P<0.05),and it was negatively correlated with starch(P<0.05).Reducing sugar was negatively correlated with lactic acid(P<0.05).Lactic acid was positively correlated with acetic acid,propanoic acid and butyric acid(P<0.05).Acetic acid was positively correlated with propanoic acid and butyric acid(P<0.05).In conclusion,the optimal adding amount of corn meal was 20%(fresh-potato: corn meal= 8:2)through analysis of the changes of pH,DM,OM,NH3-N,CP,starch,reducing sugar,lactic acid and VFA index before and after fermentation,as well as considering fermentation speed and cost factors.