GB957839A - Process and apparatus for the preparation of improved cereal flours - Google Patents

Abstract

957,839. Treating cereal grains. J-P. LEPETRE. Feb. 27, 1961 [March 1, 1960], No. 7114/61. Heading A2Q. A flour of 40% greater digestive quality than that of conventional flour and in which the starch has a substantially unbranched structure, is prepared by subjecting cereal grains to enzymatic autolysis in an aqueous acidic solution at a temperature of 15‹ to 65‹C., a pH of 4.2 to 6.8, an oxidation-reduction potential of 250 to 450, a resistivity of 115 to 180 ohms per centimetre, and an oxygen content of 2 to 6 cc. per litre of solution, and then high pressure milling the autolysed grains at an elevated temperature whereby they are substantially dried and ground to flour. Under preferred operating conditions the grains are washed in a solution acidified to pH 6.2-6.5 and given a preliminary digestion under specified conditions for up to five hours, the solution in which the enzymatic autolysis of the grains takes place is acidified initially to a pH of 4.6 with orthophosphoric acid and the grains are stirred in the solution for from 1 to 10 hours until the pH of the solution reaches the iso-electric point of the proteins of the grains, thereafter the solution is restored to a pH of about 5.6 by addition of a specified phosphoric acid, permitting the appearance in the solution of appreciable quantities of α and # amylases, and the mixture is allowed to stand for from 1 to 4 hours prior to being milled between cylinders to about 150‹C. Cereals mentioned are wheat, barley, maize, rice and rye. The grain, after washing and preliminary digestion in a column 1 during which light and heavy impurities are removed by manipulation of screens 7 and 8, respectively, passes to the autolysis column 2 provided with a thermostatically-controlled jacket 12 and probes 18, 19, for the control of the oxygen content of the liquor and of its pH, oxidation-reduction potential and resistivity, and is subsequently drained on a plate 22, dried to flour on heated rollers 30 and further dried during its passage down the conduit 33 by warm air fed through a duct 34; the dried grain may finally be treated by blade or hammer pulverisers (not shown). The autolysis liquor used in the column 2 is prepared in the auxiliary column 2a from the waste bran and middlings obtained from flour milling and drainage liquor from the column 2 collected into the three tanks 25, 26 and 27 according to its pH; the same reactions take place in the auxiliary column as in column 2, but they are allowed to go to completion until the enzymes have no further action. Parts of the apparatus in direct contact with the grains are covered with a ceramic or plastics material.