Modelling to obtain expanded cowpea products in a twin screw extruder

Abstract

Cowpea grains are nutritious and beneficial to health, contain about 25% of proteins, in addition to carbohydrates, vitamins, minerals, and bioactive compounds. Soaking the beans followed by cooking requires time availability that is incompatible with the current lifestyle. Consumers have opted for read-to-eat, attractive, healthy, nutritious and convenient foods, thus, transforming cowpeas into crispy expanded product is promising. This research aimed to evaluate the effect of the extrusion conditions, moisture, and temperature, on the physical characteristics of the extrudates developed from cowpea cotyledons flour (CCF): from cultivar BRS Guariba (Sorriso, MT, Brazil). The CCF was processed using twin-screw thermoplastic extruder ZSK 30 (Werner & Pfleiderer Co.) varying the moisture (16.2% to 21.8%) and temperature (124 to 166 °C) using Central Composite Rotatable design 22. The expansion index values ranged from 3.01 to 3.98, the regression model was not predictive, with the determination coefficient (r2) equal to 0.67. The independent variables studied presented significant effects, being water solubility index affected by the CCF moisture, compression force (15.63 to 47.72 N) affected by the extruder temperature, the water solubility index (28.34% to 43.67%) by moisture, while the specific volume (2.41 to 4.58 mL g-1) and the water absorption index (5.34 to 6.54 g g-1) were affected for both variables. By simulation, the maximum value of 1 was obtained through the global desirability test in the combination of an extrusion temperature of 124.21 °C and conditioning moisture of CCF of 16.28%. This condition favors obtaining extrudates with greater values for a specific volume and water absorption index, and lower values for compression force and water solubility index.

New Breakfast Cereal Developed with Sprouted Whole Ryegrass Flour: Evaluation of Technological and Nutritional Parameters

“…It is known that REI and BD are inversely proportional parameters, so larger air bubbles in the expanded product promote an increase in specific volume. The conditioning water acts as a plasticizer for the amorphous region of starch granules, contributing to the thermomechanical gelatinization process and favoring rheological properties and air bubble formation [31].…”

“…According to Kagan et al [38], the phenolic compounds in perennial ryegrass (Lolium perenne L.) are esterified in the cell walls and contain vacuole-soluble phenolic compounds. Kagan et al [31] evaluated perennial ryegrass from the "Calibra" and "Linn" cultivars of the Lolium genus and identified in the extracts of Linn PRG and Calibra, 5-caffeoylquinic acid (neochlorogenic acid), 3-caffeoylquinic acid (chlorogenic acid), and 4-caffeoylquinic acid (cryptochlorogenic acid). The putative peak of 3-caffeoylquinic acid (retention time of 5.2 min) was about 10 times more abundant than the peak of 4caffeoylquinic acid and the previously identified chlorogenic acid in grasses.…”