NOVELTY - Preparing mercapto short peptide metal chelate involves drying corn gluten meal or rice protein powder and crushing through 60-120 mesh sieves. The sieved material is collected and non-seived material is re-fed into the crushing mill. The sieved material is collected, screened, purified and mixed with water in the volume ratio of 1kg:10-20L. The pH is adjusted with diluted sodium hydroxide to 8.5-10.5. The obtained solution is heated to 50-65 degrees C.    USE - Method for preparing mercapto short peptide metal chelate used for preparing nutritional supplements, cosmetics, food and pharmaceutical industry. (claimed).    ADVANTAGE - The method enables to prepare cost-effective and eco-friendly mercapto short peptide metal chelate with high added values.    DETAILED DESCRIPTION - Preparing mercapto short peptide metal chelate involves drying corn gluten meal or rice protein powder and crushing through 60-120 mesh sieves. The sieved material is collected and non-seived material is re-fed into the crushing mill. The sieved material is collected, screened, purified and mixed with water in the volume ratio of 1kg:10-20L. The pH is adjusted with diluted sodium hydroxide to 8.5-10.5. The obtained solution is heated to 50-65 degrees C. Novozymes Alcalase 3.0T (RTM: liquid enzyme preparation) is added with alkaline protease for 1.5-2 hours for enzymatic hydrolysis and the mass ratio of the sieved composition is 1kg:30-50kg. The pH of the solution is adjusted with dilute hydrochloric acid to 5-6.5 after enzymatic hydrolysis stage is completed, maintaining the temperature at the same level as that of enzymatic hydrolysis reaction temperature. Papain bis grade enzyme is added for hydrolysis for 1.5-2 hours, where the ratio of papain and sieved material is 1kg:30-50kg. The solution is centrifuged at 6000-8000 rotations per minute after the hydrolysis reaction is completed. The precipitate is collected by centrifugation, dried and pulverized to obtain a material used as protein feed additive. The centrifugal supernatant is obtained to obtain hydrolyzed gluten for the next short peptide solution. The hydrolysed gluten peptide solution is collected through a nanofilter having molecular weight of 1000-3000 daltons at a pressure of 0.05-0.2MPa until the first nanofiltration retentate volume is reduced to 1/10-1/20 hydrolyzed gluten liquid volume. The nanofiltration filtrate containing soluble starch and protein is collected by centrifugation and dried to obtain protein feed additive. The first time collected nanofiltration filtrate is again pumped through a filter having molecular weight of 100-500 daltons at a pressure of 0.05-0.2MPa until the second nanofiltration retentate volume is reduced to the first 1/10-1/20 volume of nanofiltered filtrate. The second nanofiltration retentate containing an inorganic salt ions and small peptides is collected for cosmetics nutrients. The second set of nanofiltration retentate is hydrolyzed to obtain gluten peptide solution. Zinc chloride solution is prepared after obtaining gluten peptide solution by dissolving zinc in hydrochloric acid solution (2-10%) in the volume ratio of 1kg:10-20L by stirring for 1-3 hours. The obtained solution is filtered under vacuum to obtain filtrate which is then collected and diluted with pure water to a concentration of 0.1-0.5mol/L. The hydrolysed gluten peptides are added into the solution pump equipped with thiourea resins or activated ZXC610 shallow holes microspheres mercaptoethylamine modified chitosan microspheres column in the volume ratio of 1L:20-40L, where the ZXC610 thiourea resins and shallow hole microspheres mercaptoethylamine modified chitosan microspheres collectively referred to as sulfhydryl-exchange resins. The flow rate of hydrolysed gluten peptide solution is 1-4 times the column volume. The liquid passed through the column is collected and the mercapto group peptide column is exchanged to collect the liquid passed through the column. The liquid is concentrated under reduced pressure for the preparation of hair plant hydrolyzed protein concentrate. The mercapto short peptides are collected through the exchanged chromatography columns and washed with pure water. The washing liquid is collected after washing the column to collect pure water washing liquid. The column is washed after with 2-4BV zinc at a concentration of 0.1-0.5mol/L, where the flow rate of aqueous solution of zinc chloride is 1-4BV/hour and the zinc chloride aqueous solution is eluted through the column respectively. The eluent is collected, which is is mercapto peptide-based metal chelate solution for preparing next sulfhydryl peptide metal chelate lyophilized powder. The zinc chloride solution is eluted out of the column and hydrochloric acid (0.05-0.15mol/L) is added at a flow rate of 1-4BV/hour. The solution is passed through the column and regenerated by the regeneration column. The regenerated liquid in the column is collected for re-dissolving the zinc particles by preparing zinc chloride solution at a concentration of 0.1-0.5mol/L. The regenerated liquid is collected from the column for the next batch exchange mercapto short peptide. The mercapto short peptide metal chelate solution is placed in a sandwich reactor in a thermostat at 55-65 degrees C for 6-8 hours at a pH of 3-6. The chelate is placed in a dialysis machine having molecular weight of 100-500 daltons, after completion of the reaction for purification for 3-8 hours and the permeate is collected. The obtained permeate is concentrated at a pressure of 0.2-0.4MPa under reverse osmosis conditions until the volume of permeate is reduced to 1/10-1/20 of the original volume. The dilute solution of zinc chloride (0.1-0.5mol/L) is prepared for next batch concentration. The fluid is collected and placed at -45 degrees C to -55 degrees C under conditions of absolute vacuum of 35-45Pa for 36-48 hours to obtain a short peptide metal chelate lyophilized powder with purity of over 90%.