Whole nuña bean (Phaseolus vulgaris L.) flour showed higher direct expansion during extrusion processing at relatively lower temperatures.

Nuña bean, also known as "popping" bean, belongs to the group of common beans (Phaseolus vulgaris, L.). Originated in Andean mountains, nuña beans is an important food crop in several South American countries, including Bolivia, Ecuador, and Peru, where it is consumed primarily as a snack. Nuña beans are highly nutritious and have a distinctive nutty flavor, which makes them potentially desirable ingredients in food applications, such as extruded snacks. Thus, the goal of this study was to evaluate the performance of whole seed nuña bean flour during extrusion cooking. Expansion characteristics of whole nuña bean flour were investigated using a twin-screw extruder. Three levels of moisture contents of 15%, 18%, and 21% (wet basis), three barrel temperatures of 120, 140, and 160 °C, and three screw speeds of 150, 200, and 250 rpm were evaluated, with a die diameter of 3.15 mm. The expansion ratio (ER) ranged from 1.41 to 3.03, within the extrusion conditions studied. The moisture content and screw speed were found to have the most significant impact on the ER. Lower temperature and higher screw speed resulted in higher ER. The maximum ER of 3.03 was observed at a moisture content of 15%, a barrel temperature of 120 °C, and a screw speed of 250 rpm. Nuña bean flour exhibited good expansion properties at relatively low temperatures, which highlights its potential for use in extruded food applications such as nutritious snacks. PRACTICAL APPLICATION: There is increasing consumer demand for more nutritional snacks and cereals. Nuña bean flour exhibited potential for use in such nutritious products. This provides the industry with an alternative source of protein and fiber for inclusion in expanded food products.