Submitted to: Cereal Chemistry
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/22/1998
Publication Date: N/A
Citation: Interpretive Summary: Both dry heat and steam treatments are used in the processing of oat grain before milling for human consumption. These treatments have profound effects on the viscous properties that oat flour develops when mixed with water. We have experimented with the use of oat flour in bread baking and determined the effects of these different types of heat treatments on wheat/oat flour dough mixtures and on the quality of bread produced from these mixtures. We found that if oat grain is merely roasted, the bread produced is of very low quality, although if the oat grain is steamed, the bread quality is much better. Oat flour in bread doughs requires more water for mixing. The oat flour also appears to slow the staling process, possibly because the oat flour may be more resistant to a process known as reterogradation. We found that adding 10% steamed oat flour had very little adverse effects on bread quality and may provide an alternative formulation to traditional white bread.
Technical Abstract: Hydrothermal treatments, which are routine in oat processing, have profound effects on oat flour rheological properties. The influence of roasting and/or steam treatments on dough mixing and bread baking properties was investigated when hydrothermally treated oat flour was blended with wheat flour. Roasting of oat grain (105 degrees C, 2 hr) resulted in oat flours that were highly detrimental to wheat flour dough mixing properties and bread baking quality. Steaming (105 degrees C, 20 min) or a combination of roasting and steaming of oat grain significantly improved the bread baking potential of the oat flours. The addition of oat flours increased water absorption and mixing requirements of the wheat flour dough and also decreased bread loaf volume. However, at the 10% substitution level, steamed oat flours exhibited only a gluten dilution effect on bread loaf volume when wheat starch was used as a reference. Oat flour in the bread baking system decreased breadcrumb starch retrogradation rate. The results indicate that adequate hydrothermal treatments of oat grain are necessary for oat flour bread baking applications. Steamed oat flours used at a 10% level will retard bread staling without adversely affecting the loaf volume.