FLOUR QUALITY 171 U. K. or 'clear'flour in the U.S.A. Clear four is replaced chlorine in 1922 as an improving and used industrially in the U. S A for the manufac- bleaching agent for breadmaking four because ture of alcohol, gluten, starch and adhesives(see was much more effective. Its use was discontinued Ch.15) in the u.s.a. in 1949 and in the u.k. from the end of 1955, after it had been shown by Mellanby Treatments of wheat flour (1946) that flour treated with Agene in large doses ht cause le hysteria (although Agene- treated four has never been shown to be harmful ng to human health). Nitrogen trichloride reacts Flour contains a yellowish pigment, of which with the amino acid methionine, present in wheat about 95% consists of xanthophyll or its esters, protein, to form a toxic derivative, methionine and has no nutritional significance. Bleaching of sulphoximine( bentley et al., 1950). the natural pigment of wheat endosperm by oxidation occurs rapidly when flour is exposed the atmosphere, more slowly when flour is stored Chlorine dioxide in bulk and by chemical Chlorine dioxide(CIO2), known as 'Dyox',is treatment. The principal agents used, or formerly now the most widely used improving and bleaching used, for bleaching four are nitrogen peroxide, agent in the U. K, the u.s.A. Australia and chlori hlorine dioxide, nitrogen trichloride, Canada. It was first used for these purposes in nzoyl peroxide and acetone peroxide 1949 in the U.s.A. and in the u. K. in 1955. The gas is produced by passing chlorine gas through Nitrogen peroxide (NO2) an aqueous solution of sodium chlorite. Dyox gas contains a maximum of 4%CIO. The chlorine NO2 produced by a chemical reaction or by dioxide gas is released by passing air through the the electric arc process was widely used as a solution, and is applied to breadmaking flour at bleaching agent in the early twentieth century. a rate of 12-24 mg/kg (it is permitted in the U. K Its use has been discontinued except in the u.s.a up to 30 mg/kg). Chlorine dioxide treatment of and Australia, where it is still legally permitted. flour destroys the tocopherols(cf Ch. 14). The use of chlorine dioxide is also permitted in Japan Chlorine The use of chlorine gas(Cl2) for treatment of Benzoyl peroxide cake four(except wholemeal) is permitted in the (C6 CO)2O2 or BzO2 is a solid bleaching U.K. to a maximum of 2500 mg/kg. The chlorine agent which was first used in 1921. It is supplied modifies the properties of the starch for high- as a mixture with inert, inorganic fillers such as ratio cake flour (cf p. 178). For cake flours the CaHPO4, Ca3(PO4)2, sodium aluminium sulphate usual level of treatment is 1000-1800 mg/kg. The or chalk Novadelox, a proprietary mixture, con Bread and Flour Regulations 1984 do not permit tains up to 32% of benzoyl peroxide but 16% is its use in bread flour in the U. K. The use of the usual proportion. The dosage rate, normally chlorine is not permitted in most European 45-50 mg/kg, is restricted to 50 mg/kg in the countries, but it is allowed in four for all purposes U. K. by the Bread and Flour regulations 1984 in the u.s.A., Canada, Australia, New Zealand The bleaching action occurs within about 48 h (to 1500 mg/kg)and South Africa(to 2500mg/kg) his bleacher has the advantage over gaseous agents that only a simple feeder is required, and Nitrogen trichloride storage of chemicals presents no hazard; the fact that it has no improving action is advantageous This gas(NCl3), known as 'Agene,, was patented in the bleaching of patent fours. The treated flour s a four bleach by j. C. Baker in 1921, and contains traces of benzoic acid but objection hasFLOUR QUALITY 171 replaced chlorine in 1922 as an improving and bleaching agent for breadmaking flour because it was much more effective. Its use was discontinued in the U.S.A. in 1949 and in the U.K. from the end of 1955, after it had been shown by Mellanby (1946) that flour treated with Agene in large doses might cause canine hysteria (although Agene￾treated flour has never been shown to be harmful to human health). Nitrogen trichloride reacts with the amino acid methionine, present in wheat protein, to form a toxic derivative, methionine sulphoximine (Bentley et al., 1950). Chlorine dioxide Chlorine dioxide (C102), known as ‘Dyox’, is now the most widely used improving and bleaching agent in the U.K., the U.S.A., Australia and Canada. It was first used for these purposes in 1949 in the U.S.A. and in the U.K. in 1955. The gas is produced by passing chlorine gas through an aqueous solution of sodium chlorite. Dyox gas contains a maximum of 4% C102. The chlorine dioxide gas is released by passing air through the solution, and is applied to breadmaking flour at a rate of 12-24 mg/kg (it is permitted in the U.K. up to 30 mg/kg). Chlorine dioxide treatment of flour destroys the tocopherols (cf. Ch. 14). The use of chlorine dioxide is also permitted in Japan. Benzoyl peroxide (C6H5C0)202 or Bz02 is a solid bleaching agent which was first used in 1921. It is supplied as a mixture with inert, inorganic fillers such as CaHP04, Ca3(P04)2, sodium aluminium sulphate or chalk. Novadelox, a proprietary mixture, con￾tains up to 32% of benzoyl peroxide but 16% is the usual proportion. The dosage rate, normally 45-50 mg/kg, is restricted to 50 mg/kg in the U.K. by the Bread and Flour Regulations 1984. The bleaching action occurs within about 48 h. This bleacher has the advantage over gaseous agents that only a simple feeder is required, and storage of chemicals presents no hazard; the fact that it has no improving action is advantageous in the bleaching of patent flours. The treated flour contains traces of benzoic acid, but objection has U.K. or ‘clear’ flour in the U.S.A. Clear flour is used industrially in the U.S.A. for the manufac￾ture of alcohol, gluten, starch and adhesives (see Ch. 15). Treatments of wheat flour Bleaching Flour contains a yellowish pigment, of which about 95% consists of xanthophyll or its esters, and has no nutritional significance. Bleaching of the natural pigment of wheat endosperm by oxidation occurs rapidly when flour is exposed to the atmosphere, more slowly when flour is stored in bulk, and can be accelerated by chemical treatment. The principal agents used, or formerly used, for bleaching flour are nitrogen peroxide, chlorine, chlorine dioxide, nitrogen trichloride, benzoyl peroxide and acetone peroxide. Nitrogen peroxide (NO,) NO2 produced by a chemical reaction or by the electric arc process was widely used as a bleaching agent in the early twentieth century. Its use has been discontinued except in the U.S.A and Australia, where it is still legally permitted. Chlorine The use of chlorine gas (C12) for treatment of cake flour (except wholemeal) is permitted in the U.K. to a maximum of 2500 mg/kg. The chlorine modifies the properties of the starch for high￾ratio cake flour (cf p. 178). For cake flours the usual level of treatment is 1000-1800 mg/kg. The Bread and Flour Regulations 1984 do not permit its use in bread flour in the U.K. The use of chlorine is not permitted in most European countries, but it is allowed in flour for all purposes in the U.S.A., Canada, Australia, New Zealand (to 1500 mg/kg) and South Africa (to 2500mg/kg). Nitrogen trichloride This gas (NC13), known as ‘Agene’, was patented as a flour bleach by J. C. Baker in 1921, and