Food Structure


In high-temperature short- time extrusion cooking with a twin screw extruder , effects of oil addition to defatted soybean flour and microstructural transformation of full - fat soybean flour during cooking , were investigated by use of a light microscope. At levels up to 15% , soybean oil was distributed in the protein and carbohydrate matrix as small, spherical drops under the experimental conditions used in this study. However , oil contents above 15% significantly prevented formation of well-aligned fibrous structures in the extrudates . During extrusion cooking , the starting materials began to break down by shearing and kneading forces in the feed section but gross cellular structures remained up to the cooking zone. After being introduced into the cooking zone , protein and carbohydrate were plasticized and appeared to be stream-like . Passage through the breaker plate and long cooling die induced formation of a fiber-like extrudate.

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