Pasting Properties of Cowpea Flour:  Effects of Soaking and Decortication Method

Abstract

Pasting properties of flour prepared from 12 diverse cowpea varieties as affected by dry and wet decortication processes were determined using a Brabender viscoamylograph. Dry decorticated flour (DDF) was prepared from seeds wetted, dried, and mechanically dehulled; wet decorticated flour (WDF) was prepared from seeds soaked, manually decorticated, dried, and milled to flour. No pasting peak was obtained during heating of flour slurry to 95°C for both DDF and WDF for all cowpea varieties. WDF samples had higher paste viscosities than DDF samples. Presoaking of seeds (2, 4, 8, or 16 h) affected paste viscosities, especially hot paste viscosity (HTPV), and particle size distribution. Maximum HTPV and highest quantities of medium-size particles (mesh 40-80, 0.42-0.177 mm) were attained with flour prepared from seeds presoaked for 4 h. Presoaking for more than 4 h did not yield further increase in HTPV. Cowpea flour with at least 65% of medium-size particles exhibited the best hydrothermal properties, leading to increased rate of moisture absorption and higher HTPV during aqueous heating of slurry.

Functional, thermal and pasting characteristics of flours from different lentil (Lens culinaris) cultivars

“…PT of 73.1-75.2°C in chickpea (Kaur and Singh 2005), 68.9-81.1°C in black gram , and 78-83°C in cowpea fl our (Henshaw et al 1996) have been reported. The high pasting temperature of 'LL 147' fl our indicates the presence of starch in this fl our that is highly resistance to swelling and rupturing.…”

“…The highest SV of 'LL 912' fl our indicates its higher tendency to retrograde. Flour with high hot paste viscosity would be advantageous in products requiring viscosity increase after cooking such as soups, sauces, and puddings (Henshaw et al 1996). Although starch is quantitatively major component to control the pasting /thermal properties, temperature induced changes in non starchy polysaccharides and proteins also contribute to the gelling, and pasting properties by way of swelling, denaturation and unfolding.…”

“…Sosulski et al (1976) investigated the functional properties of ten legume fl ours, and found some properties of mung bean fl our to be comparable with soybean fl our. Henshaw et al (1996) reported that the functionality of cowpea fl our can be attributed to its chemical components as determined by the genetic architecture of seed and post-harvest conditions of storage and processing.…”

“…Gelatinization is an order-disorder phase transition that involves diffusion of water into the starch granules, hydration and swelling, uptake of heat, loss of birefringence and crystallinity, and amylose leaching (Biliaderis et al 1980). Henshaw et al (1996) reported that fl our contains other substances such as protein, lipid, and minerals that may interact with starch to varying degrees and affect the paste characteristics. The variation in fl our properties between lentil cultivars have not been the subject of a detailed study Kaur M. 1 .…”

Thermal, Pasting and Rheological Properties of Processed Buckwheat (Fagopyrum Esculentum) Flour

“…The process of gelatinization can be monitored using differential scanning calorimeter (DSC). Henshaw et al [5] studied that apart from starch flours also contain lipids, protein, and minerals that may interact with starch to varying degrees and effect the gelatinization and pasting properties. The rheological properties of flours are very useful for the preparation of different products with desirable attributes.…”