The effect of extrusion cooking on mineral bioavailability in pea and kidney bean seed meals

The effects of extrusion cooking on chemical composition, contents of miner als, carbohydrates and antinutritional factors (inositol phosphates, conden sed tannins and lectins) in pea (Pisum sativum L.) and kidney bean (Phascol us vulgaris L.) seed meals were investigated. In addition, mineral bioavail ability in growing rats of diets based on extruded or raw pea or kidney bea n meals, as the only protein source was determined. Moisture content decreased and iron increased in extruded compared with non -treated seed meals. Starch and NSP were reduced (P < 0.05) in both pea and kidney bean seed meals. Raffinose, stachyose and verbascose also dropped i n kidney bean meal after extrusion, but only stachyose was reduced by therm al treatment in pea flours. Inositol hexaphosphate was partially hydrolysed to penta- and tetraphosphates by extrusion, which also lowered tannin and lectin content (P < 0.05). The apparent absorption of Fe, Ca and P from uns upplemented pea-based diets significantly increased in extruded compared wi th raw seed meals. With amino acid supplemented pea diets, extrusion signif icantly (P < 0.05) increased Ca, Mg, Fe, Cu and P apparent (faecal) absorpt ion in rats. Extrusion increased (P < 0.05) Ca, Mg, Zn, Cu and P apparent ( faecal) absorption in rats fed with both unsupplemented and supplemented ki dney bean-based diets. (C) 2001 Elsevier Science B.V. All rights reserved.