Patent GB-685376-A (GB)
Title: Protein hydrolysis product
Filed: 1949-10-25
Abstract: Hydrolysis products of gluten are prepared by hydrolysing in a closed vessel a purified gluten, obtained by treatment of commercial gluten to free it from starch and starch degradation products, with sufficient of an aqueous suspension of lime to give a pH of 9 to 13.5 at a temperature of 115 DEG  to 135 DEG  C. by external heating or by passing steam into the liquor at a steam pressure of 25 to 45 lbs. per sq. in. for a period within the range of 20 minutes to 2 1/2 hours, removing undissolved protein, treating the liquid containing dissolved hydrolysed protein and lime with acid to neutralize the lime and separating the desired product from the resulting acid or neutral liquor.  As starting material may be used gluten from wheat, Kaffir corn, milo maize or corn (Zea Mays L.).  Processes described with reference to a flow sheet (not shown) comprise dewatering commercial gluten, acidifying the concentrated product with an acid, e.g. sulphuric, to a pH of 2-2.7 and hydrolysing in an acid-resistant converter for 15 minutes at an internal steam pressure of 30-45 lbs. per sq. in., neutralizing to pH 4.5 and filtering and washing the product to remove the solubilized starch degradation products; the now starch-free product is then mixed with water and lime to give a preferred pH of 11.8 and the alkaline hydrolysis is effected. This hydrolysis and subsequent treatment may be carried out to provide a product suitable as a filler for leather goods or a coating on glass, e.g. photographic plates.  Thus in examples: (1) the alkaline hydrolysis is effected at 35 lbs. steam pressure by injection of live steam for 1 hour, undissolved protein suitable as an animal feed is filtered off, dissolved calcium is then precipitated as the sulphite by passing in SO2, the precipitate is removed and the filtrate acidified to pH 7.0-4.0, whereupon, after concentration, a protein plasticizer, e.g. lactic acid, propylene glycol or glycol esters, and a small amount of an oxidizing agent, e.g. hydrogen peroxide are added and the product dried to a powder.  The product is soluble in aqueous solvents having a pH of 4.5 or more; it is precipitated from aqueous solution by tannic acid at a pH of 5.0 or less and the precipitate may be converted into a plastic mass by heating to 80 DEG C.; the product may be added in a soluble form to leather and then made insoluble; (2) the alkaline hydrolysis is effected as in (1) for only 30 minutes, whereupon the product is filtered, the filtrate treated with hydrochloric acid to give a pH of about 3.5 and then heated at 120 DEG  F. e.g. for 15 minutes; a tarry precipitate results and this may be dissolved in alcohols containing 10-20 per cent water providing a solution for coating photographic plates (see Group XX); this product is insoluble in water but soluble in dilute ammonia or sodium carbonate solution.  Specification 517,767 is referred to.ALSO:Components for animal feeds are obtained as by-products in a process for the production of hydrolyzed proteins wherein a commercial gluten, preferably from maize, is subjected to an acid hydrolysis which converts starch and starch degradation products present into a high protein corn syrup which may be used as stock feed, this being separated from the unchanged purified gluten; the gluten is then subjected to hydrolysis by means of an aqueous suspension of lime under specified conditions (see Group IV (b)), and, after neutralisation, an aqueous solution of the hydrolyzed gluten is separated from unreacted protein, the latter serving as animal food.