15D-9 |
Evaluation of extruded black bean Phaseolus vulgaris L. processed under different screw speeds and particle sizes |
J. D. J. BERRIOS, USDA, Albany, CA 94710 and J. L. Pan, USDA-ARS-WRRC, Albany, CA 94710. Black beans Phaseolus vulgaris L. provide a significant source of macro- and micronutrients important to a healthy diet. However, their use remains limited to specific ethnic groups and they are considered largely a commodity product. The nutritional appeal of high protein, high nutritional, low-caloric snacks, is a value-added attribute to extruded products from plant origin such as black beans. The objective of this study was to evaluate the effect of extrusion processing at different screw speeds on some physicochemical parameters of black beans ground at different particle sizes. Black beans were reduced to flours using a hammer mill, with different screen sizes, and a pin mill. The bean flours were processed in a twin-screw extruder equipped with eight barrel sections, each with a length of 160 mm. The die contained two circular openings 3.5 mm in diameter. The screw configuration, heating profile, and water addition were kept constant in this study. However, the extruder's screw speed was varied to 400, 450, and 500 rpm. Our results showed that as the extruder's screw speed increased from 400 to 500 rpm, the torque increased from 64-80% and the die pressure decreased from 300 to 30 psi, independent of the particle size of the flour. It also showed that the fine-ground bean flours produced extrudates with significantly higher expansion ratio than the extrudates from medium- and coarse-ground flours. These expanded products had acceptable appearance for snack products. The pasting viscosity of the bean flours and electrophoretic pattern of the bean protein were not significantly affected by the processing conditions under study. The favorable characteristics of extruded black bean products as produced in this study demonstrate the feasibility of developing value added products for California bean growers, which will expand the marketability of black beans in local and international markets.
Session 15D, Food Engineering: Processing Technologies
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