Changes in available methionine and tryptophan contents during cereal flake production

Abstract

The changes in available methionine and tryptophan contents during industrial production of wheat, rye, barley and oat flakes have been investigated. The contents of available methionine and tryptophan were lowered significantly (p = 0.05) under conditions of technological processing. The total decrease in available methionine ranged from 13 to 26% and tryptophan from 10 to 20%. Hydrothermal treatment (120 °C, 60 min, 1.99 × 105 Pa) of whole cereal grain had a considerable impact on the damage to available methionine, but the highest decrease in tryptophan was determined after the flaking process (70 °C, 0.3 mm gap). The total decrease in these amino acids correlates significantly (p = 0.001) and positively with values for lipid oxidation products, expressed on a total lipid basis, in cereal flakes as well as in untreated cereal grains. Available methionine and tryptophan contents in proteins of cereal flakes equalled or exceeded requirements for adults recommended by the FAO 1985 reference pattern. © 2000 Society of Chemical Industry