Composition of volatile flavor obtained from polished-graded flours and breads by a steam distillation method
1Osaka Prefecture University, Sakai, Japan,
2Hyogo University of Teacher Education,
Katou-gun, Japan Polished-graded flours were obtained from the outer layer to the inner layer of whole wheat grains using a gradually polishing method. Because the polishing procedure was conducted without debranning and removing germ and different from a conventional milling method, thus prepared flours have various benefits with high nutritional and functional values, as compared with common milled flours (CW). However, the presence of unfavourable flavours derived from bran and germ in polished flours is one of some difficulties for its practical application to processed foods. To resolve the problem, it is necessary to identify flavour components of polished flours and breads. Therefore, the flavor components in polished flours of three fractions, C-1 (100-90%), C-5 (60-50%), C-8 (30-0%) and their breads were collected by steam distillation, then analysed by gas chromatograph-mass spectrometry. The volatile flavours of C-1, C-5 and C-8 flours contained higher compositions of acid, alcohol and aldehyde, respectively and the result of C-8 was similar to that of CW. In the polished flours, the contents of 1,6-heptadien-4-ol, 3-hydro-2-butanon, nonalactone and ionone were higher than CW. The C-5 included large amounts of hexanol, 3-methyl-1-pentanol and benzyl alcohol, and C-1 and C-8 had large amounts of (E)-2-heptenal and propionaldehyde. After baking, the ratio of alcohol, aldehyde and ketones in total compositions increased in C-1 bread. Bread samples made from C-1 and C-8 flours contained large amounts of hexanol and 1,6-heptadien-4-ol, respectively, and also the both breads contained larger amounts of 3-hydro-2-butanone as compared with CW.