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

Objective: To compare starch digestibility from a maize-soy blended food wi th and without extrusion cooking. Design: Resistant starch, soluble and insoluble dietary fibres were measure d in vitro before and after extrusion. Starch digestibility was assessed in 8 volunteers who took, in a randomised order, a test meal with either 100g extruded (EF) or non-extruded (NEF) blended flour cooked 15 min at 80 degr ees C in 500 ml of water. Setting: Research ward for healthy volunteers. Subjects: Healthy volunteers. Main outcome measures: Starch digestibility w as measured by C-13 enrichment of breath samples for 8 h. Breath H-2 concen tration was measured during 12 h to assess bacterial fermentation in the co lon, Volunteers reported hunger on a visual stale every hour for 8 h. Results: In vitro resistant starch, soluble and insoluble dietary fibers we re higher in NEF than in EF (5.4 vs 1.1, 0.7 vs 0.5, and 13.3 Is 10.4% dw r espectively). In vivo, the area under curve (AUC) for (13)CO2 excretion dur ing 8 h was not significantly different for NEF and EF (10.3 +/- 1.3 rs 9.1 +/- 0.5 mmol/min, respectively). AUC far H-2 excretion during 12 h was sig nificantly higher for EF than for NEF (26.9 +/- 5.6 is 14.1 +/- 4.7 mL, P < 0.05). AUC for satiety was marginally higher with EF (12.6 +/- 1.6) than f ur NEF (10.0 +/- 2.1) (P = 0.06). Conclusions: Extrusion cooking does not seem to substantially improve blend ed foods digestibility. Extrusion of high fibre flours may promote carbohyd rate fermentation in the colon and increase satiety. Sponsorship: Supported by a grant From Nutriset (Malaunay, France) and ANVA R (Agence Nationale de la Valorisation de la Recherche, Contract No A970302 1P). Descriptors: starch digestion; extrusion cooking; blended flours, humans.