Preparation Of Corn Peptide From Corn Germ Meal By Microbes Solid-state Fermentation

After corn germ oil is extracted, corn germ meal is the primary by-product, and itscrude protein content is approximately20%. Currently most corn germ meal is used forfeed or directly discarded, and its potential economic value is not developed. Cornpeptide has multiple biological active, such as lowering blood pressure and promotingthe metabolism of ethanol. If corn germ meal with low added value can be transformedinto corn peptide with high added value through certain means, and it has importantsignificance on the comprehensive utilization of corn and corn peptideindustry.Through the operation of protease Aspergillus niger and Aspergillus oryzaersecret, corn germ meal was fermented to into bioactive peptide.The main results are shown as follows：(1) After a series of single factor Box-Behnken experiments, the optimumconditions for preparation of corn peptides by Aspergillus niger ferment corn germmeal were obtained as follows： corn germ meal50%(bran50%), medium moisturecontent70%, medium inoculation content12%, fermentation time96h, fermentationtemperature30℃. Under these conditions, the maxium conversion rate of cornpeptides was about30%; the optimum conditions for preparation of corn peptides byAspergillus oryzaer ferment corn germ meal were obtained as follows： corn germmeal39%(bran61%), medium moisture content70%, medium inoculation content8%,fermentation time95h, fermentation temperature30℃. Under these conditions, themaxium conversion rate of corn peptides was about37%.Through the contrast betweenthe corn peptide conversion rate and total sugar content, and finally Aspergillusoryzaer was selected to produce corn peptide.(2) Separation and purification of preliminarily corn peptides were obtained byultrafilrate (molecular mass104) and Sephadex G-25. Two peaks were eluted and theirmolecular weight are around5128and1626Da after calculation. In order to identifythe purity of the two components, Tricine-SDS-PAGE was used in the experiment. Theresults were consistent with the results that obtained before.As a result of reducingsugar content of corn peptide extraction is high, thus Sephadex G-25were used toremove it, finally the optimal conditons were determined.(3) The nature of corn peptide（Separation and purification by ultrafilrate andSephadex G-25） was researched, it include the composition analysis of amino acid, oxidation resistance, solubility, viscosity, the results indicate that the corn peptideobtained is a good biological active peptide.