The role of lipids in baking. IV. —Some further properties of flour lipids and defatted flours

Flours recently examined have sometimes shown different characteristics from those previously described. Conflicting results on the breadmaking quality of defatted flours are attributed, from an examination of different flour‐milling products, to differences in the condition of the wheats constituting the grist and to the flour extraction rate, although the latter is not the controlling factor. Several methods of fractionating flour lipids and investigating the baking properties of various fractions are described. Countercurrent distribution of flour lipids is shown to be a useful systematic method of study, some of the tractions having markedly differing effects on bread properties. Further experiments on oxidative flour treatments have indicated that the flour lipid extracted by carbon tetrachloride is little affected by such treatments. The total lipid may, however, be involved in the mechanism of oxidative improvement. Dough and baking tests on undefatted flours and defatted flours in which the extracted lipids have been replaced indicated that the original nature of the flour lipid cannot be fully restored. The ultra‐violet absorption spectra of the lipids from different wheat‐milling products and breads are described and it is shown that such spectra might be used to indicate ( a ) the bran content of a flour and ( b ) whether a treated flour has been used in bread production. It is clear from the complicated picture emerging from the results hitherto obtained, that until far more is known of the constitution of flour and the effect of the many factors contributing to its constitution, experimental dough and baking tests remain the best means of assessing flour quality for breadmaking.