Method for the production of iodinated proteins with a determinated iodine content

A method for the production of iodinated proteins and/or protein hydrolyzate, comprising:

• providing a source protein raw material for the iodination process;
• mixing the source protein raw material with an aqueous inorganic iodine solution in a selected inorganic iodine/source protein raw material proportion of 2:1 to 40:1;
• reacting the source protein raw material with the aqueous inorganic iodine solution by mixing with a buffer solution comprising a mixture of NaCl, Na and K phosphates, and an enzyme reaction mixture comprising enzymes that are immobilized on semipermeable membranes or on inert supports;
• wherein the reaction process is carried out while continuously monitoring the iodine content of the solution, and the aqueous solution comprising the iodinated protein and/or protein hydrolyzate is purified of the macro and micro impurities, including of the inorganic iodine, using the process comprising macrofiltration, microfiltration and ultrafiltration followed by a subsequent diafiltration to obtain purified iodinated protein and/or protein hydrolysate;
• subjecting the purified iodinated protein and/or protein hydrolysate to an sterilizing micro filtration step, followed by sublimation or spray drying to obtain a finished, powdered iodinated product comprising covalently bound iodine content of 0.5-4.0% wt;
• wherein the iodination reaction is carried out at a temperature of 20° C.-40° C. using the buffer solution comprising NaCl, 14-18% wt of sodium phosphate and 22-28% wt of potassium orthophosphate, and the enzymes reaction mixture having solution stability of pH 6-8 comprising 16 24% wt of horseradish peroxidase and 14-21% wt of catalase, with remainder being lactoperoxidase;
• and
• wherein the ultrafiltration of the aqueous solution comprising iodinated protein and/or protein hydrolyzate in an ultrafiltration unit is carried out in a tangential flow-through mode using membrane modules with a cutoff limit of 300-800 Da at pH 6.0-8.0.