Distribution of enzymes in wheat flour mill streams

The distribution of alpha-amylase, protease, lipoxygenase, polyphenol oxidase and peroxidase in wheat roller flour mill streams was studied. Break flours had relatively less alpha-amylase and protease activity than reduction flours both on flour weight and a protein basis. Among the different flour streams, the 5(th) and 6(th) reduction passage had the highest alpha-amylase activity, while the 4(th) reduction passage had the highest protease activity. The lipoxygenase activity was concentrated mostly in the last break and the reduction streams, whereas polyphenol oxidase activity was highest in break flour streams. Peroxidase activity was distributed unevenly among the different mill streams. The lipoxygenase, polyphenol oxidase and peroxidase were highly concentrated in different bran fractions. Except for protease, the other enzymes were concentrated in the 'atta'. a milling by-product comprising refined flour, bran and shorts and are least active in semolina (farina). (C) 2001 Academic Press.