PHYSICAL-PROPERTIES OF EXTRUDED WHEAT STARCH-ADDITIVE MIXTURES

The effects of the addition of fatty acids, monoglycerides (MG), and w heat germ oil (WGO) on the level of crystallinity and the crystalline structure of extrusion-cooked wheat starch have been studied using twi n-screw extruders. Measurements of water solubility and water absorpti on indices were made on the extrudates, together with specific mechani cal energy (SME) consumption and die pressure for the extruder. MG and the fatty acids added to a level of 4% caused an increase in V-hydrat e type crystallinity. WGO addition to a level of 8% caused no change i n crystallinity, although the E-hydrate type was favored at lower mois ture contents. All additives caused a decrease in SME and an increase or maximum in die pressure. WGO behaved differently than MG and fatty acids in that its addition caused the water solubility index and expan sion to increase, as previously observed for other oils added to flour s.