USE OF EXTRUSION TECHNOLOGY TO OVERCOME UNDESIRABLE PROPERTIES OF HARD-TO-COOK DRY BEANS (PHASEOLUS-VULGARIS L)

he objective of this work was to study the effects of extrusion cookin g on improving the functional and nutritive properties of dry beans th at had been stored, at 23 +/- 3 degrees C and 65 +/- 5% relative humid ity for 12 months. After storage, the bean cooking time increased 4.5- fold, while texture and flavor deteriorated in quality. Water absorpti on, water solubility, and emulsifying capacity were the same for the e xtrusion cooked beans, before and after storage. Paste viscosity was s lightly higher for the beans extruded shortly after harvest. Protein n utritive value of the freshly harvested beans was totally preserved in the stored beans submitted to extrusion cooking. Extruded mixed flour s (1:3 w/w) of freshly harvested beans and rice or stored beans and ri ce, respectively, improved significantly in their water absorption cap acity, viscosity of paste at 25, 90, and 50 degrees C, and nutritive v alue, but decreased in water solubility index and in emulsifying capac ity, in relation to extruded flours of beans alone.