Comparison of starch digestibility of a blended food prepared with and without extrusion cooking.

Abstract

To compare starch digestibility from a maize-soy blended food with and without extrusion cooking. Resistant starch, soluble and insoluble dietary fibres were measured in vitro before and after extrusion. Starch digestibility was assessed in 8 volunteers who took, in a randomised order, a test meal with either 100 g extruded (EF) or non-extruded (NEF) blended flour cooked 15 min at 80 degrees C in 500 ml of water. Research ward for healthy volunteers. Healthy volunteers. Starch digestibility was measured by 13C enrichment of breath samples for 8 h. Breath H2 concentration was measured during 12 h to assess bacterial fermentation in the colon. Volunteers reported hunger on a visual scale every hour for 8 h. In vitro resistant starch, soluble and insoluble dietary fibers were higher in NEF than in EF (5.4 vs 1.1, 0.7 vs 0.5, and 13.3 vs 10.4% dw respectively). In vivo, the area under curve (AUC) for 13CO2 excretion during 8 h was not significantly different for NEF and EF (10.3+/-1.3 vs 9.1+/-0.5 mmol/min, respectively). AUC for H2 excretion during 12 h was significantly higher for EF than for NEF (26.9+/-5.6 vs 14.1+/-4.7 mL, P<0.05). AUC for satiety was marginally higher with EF (12.6+/-1.6) than for NEF (10.0+/-2.1) (P=0.06). Extrusion cooking does not seem to substantially improve blended foods digestibility. Extrusion of high fibre flours may promote carbohydrate fermentation in the colon and increase satiety.