Extrusion of minced catfish with corn and defatted soy flours for snack foods

Response surface methodology (RSM) with a rotatable central composite design was used to determine an extrusion condition that would produce extrudates of a maximal expansion ratio from blends of catfish flesh (20%), corn flour and defatted soy flour (DSF) using a single-screw laboratory extruder Feed moisture, process temperature and DSF level were selected as independent variables. Analyses of the response indicated that the combination of 26.9% moisture, 160.1C and 4.95% DSF would result in extrudates with maximal expansion. The snack food made with the aforementioned combination and 74.74% corn flour in feed was slightly less dense than malted milk balls and much less hard than cocktail peanuts, according to a trained sensory panel. "Grain complex" was the most intense flavor note. When 1% garlic or onion powder was added to the feed formulation, the spice flavor notes were detected in extrudates. No fish flavor note was perceived in any of the extrudates.