Extrusion and Boiling Improve Rat Body Weight Gain and Plasma Cholesterol Lowering Ability of Peas and Chickpeas

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This study investigated the effect of feeding peas (Pisum sativum) and chickpeas (Cicer arietinum) processed by boiling or extrusion on growth performance, plasma cholesterol concentrations and organ weights of rats. Casein was used as the protein source in the control diets. Complementarity of wheat and legumes on protein quality was also evaluated. Boiled or extruded legumes significantly increased body weight gain (BWG) of rats but not protein efficiency ratio (PER) when compared with raw legumes. Rats fed processed chickpeas and those fed casein had similar BWG, and both groups had greater BWG than rats fed peas. Extruded wheat combined with peas or chickpeas increased sulfur amino acid (SAA) levels in the diets and significantly improved BWG and PER of rats compared with those fed sucrose as an energy source. There was a linear correlation between the SAA to dietary protein ratio and BWG of rats (r = 0.902, P < 0.014), indicating that SAA are the limiting amino acids in legumes. Plasma cholesterol concentrations were lower in rats fed legumes than in those fed casein. Cholesterol-lowering ability was affected by processing method, with extrusion being most effective for peas; boiling and extrusion were equally effective for chickpeas. Raw legume feeding resulted in greater pancreatic and small intestine weight relative to body weight. Chickpea fed rats had lower spleen, thymus and liver relative weights and higher cecum and colon relative weights than rats fed casein. There were no differences in growth, PER, organ relative weight or plasma cholesterol concentration between rats fed extruded legumes and those fed boiled legumes, suggesting that extrusion improves nutritional value of these legumes to the same extent as the traditional boiling method.