Possible Role of the Crude Fiber of Soy Flour in Texture Formation During Nonextrusion Texturization Processing

Abstract

ABSTRACTScanning electron and transmitted light microscopy were used to study the role of crude fiber in texture formation during non‐extrusion processing of soy flour. By comparing micrographs of texturized soy flour, water‐extracted texturized soy flour, texturized soy concentrate, texturized soy isolate, and texturized soy product‐hull blends, transmitted light and scanning electron microscopy showed that removal of the soluble carbohydrate fractions either before or after nonextrusion texturization did not alter the morphology or microstructure of the texturized soy concentrate or water‐extracted texturized soy flour as compared to texturized soy flour. Therefore, it seems probable that the presence of the soluble carbohydrate fractions is not a prerequisite for the formation of the alveolate morphology normally created during nonextrusion processing. Scanning electron microscopy showed that the cuticle morphology of the texturized soy isolate's alveoli was changed as the amount of crude fiber in the soy hull‐soy isolate blend increased. The cuticle morphology of the texturized soy isolate‐soy hull blend was similar to that of the texturized soy concentrate and texturized soy flour. Therefore, crude fiber seems to control the type of alveolation developed and the type of cuticle morphology exhibited in the product's alveoli.