Grains of Vigna unguiculata (L.) Walp., show better nutritional balance than cereals and extrusion cooking is a versatile alternative to transform it into ready to eat products.
Cotyledons of “Novaera” were ground in a MFC-180-75-01 n°5753 (Renard) Wiley mill coupled with a sieve (3 mm), followed by particle size reduction in a Quadrumat Senior (Brabender) roller break mill and processed in a ZSK-30 (Werner & Pfleiderer Co.) co-rotating intermeshing twin-screw extruder. Temperatures of the 1st zone (75°C), 2nd zone (100°C), 3rd zone (always 10°C bellow the 4th zone), die with two orifices ( 2.8mm), feed rate (13kg/hour) and screw speed (260 rpm) were used. A Central Composite Rotatable Design (CCRD) was used and the data analyzed by Response Surface Methodology to evaluate the effects of 4th zone temperature (124; 130; 145; 160 and 166°C) and moisture content (16.16; 17; 19; 21; and 21.84%).Were the ranging and respectively coefficient of determination (R2): expansion index from 2.69-3.24 (0.37); L* value 41.02-52.01 (0.66); a* value 6.21-13.74 (0.73); b* value 23.50-26.94 (0.47); Water Solubility Index (WSI) 28.15-52.07% (0.87); Water Absorption Index (WAI) 489.10-726.88% (0.68), compression force 18.09-37.55N (0.12). The rheological parameters in the RVA 4500 using Extrusion-2 Profile showed viscosity values for cold to peak ranging from 365.00-655.00cP (0.58); raw peak 396.00-991.00cP (0.83); hold 109.00-288.00cP (0.97); breakdown 285.00-703.00cP (0.69); final viscosity 393.00-811.00cP (0.97); setback 284.00-523.00cP (0.97); cold peak area 372.00-695.00 (0.31). Hold, final viscosity and setback were affected by all effects (linear, quadratic and interactions) (p<0.05). WSI and breakdown were affected by linear effect of the moisture content, and WAI by quadratics effects (p<0.05) of the moisture content. The value of raw peak area of extrudate flour were affected by linear effects of moisture and temperature (p<0.05). These results to be valuable for optimization of the development of snacks products of cowpea cotyledons.