TOASTING AND HEXANE:ETHANOL EXTRACTION OF DEFATTED SOY FLAKES Flavor of Flours, Concentrates and Isolates

Flours and protein concentrates, prepared from defatted soybean flakes steamed up to 20 min before or after extraction with hexane:ethanol azeotrope 82/18 v/v, were presented to a 15-member trained taste panel. Flavors and odors were described and rated for intensity on a scale of 1 to 10 where 1 is strong and 10 is bland. Azeotropic extraction for 6 hr by itself significantly affected flavor of flours and of concentrates so that they scored 7.4 and 6.8, respectively, compared to 4.0 for raw, hexane-defatted, soy flour. Toasting after azeotropic extraction raised flavor scores of flours and protein concentrates to 7.9, a value which compares favorably with 8.1 for wheat flour. Toasting is also necessary to inactivate trypsin inhibitors and other antinutritional factors in azeotropio-extracted soybean flakes. A protein isolate from toasted, azeotropio-extracted flakes scored 7.3 compared to 8.0 for sodium caseinata Yields of protein isolates are good if the heatprocessed fiakes are extracted with hot water at 74°C and pH 7.2.