Effect of Milling and Particle Size on Functionality and Physicochemical Properties of Cowpea Flour

Abstract

Cereal Chem. 77(2):213-219Cowpeas (Vigna unguiculata) were milled through 0.5-, 1.0-, and 2.0mm screens, and the flour was subsequently separated into different particle-size ranges. Such procedures caused only minimal changes in moisture, fat, protein, ash, and total carbohydrate. The amount of extractable starch, however, varied from 34.5 to 52%. The effects of both mill screen and sieve mesh size were significant (P < 0.05). Differences in milling and separation procedures resulted in significant variations in water absorption (0.41-2.81 g of water/g of flour), solids lost (0.34-1.17 g/g of flour), and protein solubility (21.2-37.4%) (P < 0.05). Finely milled flours (91% moisture) had lower initial gelatinization temperatures (70-73°C), as measured by differential scanning calorimetry (DSC) (P < 0.01). Gelatinization peaks in high-moisture flour were similar to that of pure starch. At lower moisture, a second peak was observed indicative of protein. Light-scattering analysis showed that different conditions produced a bimodal particle-size distribution when samples were suspended in water. The small size had relatively constant diameters (19-21 µm) and was associated with starch granules. The latter had a large size distribution and varying peak size and was associated with aggregated flour particles. These results indicate that changes in processing produces cowpea flours with differing chemical and physical properties.

Relationships of damaged starch granules and particle size distribution with pasting and thermal profiles of milled MR263 rice flour

“…Same pattern was observed by Kerr, Ward, McWatters, and Resurreccion (2000), whereby the smaller size particles consist of suspended starch granules, while the larger particles correspond to undissociated or partially dissociated flour particles. When comparing the curve of dry and semi-wet grinding flour, the former exhibits a peak shifted to the left and the later shifted to the right.…”

A comparison in rheological, thermal, and structural properties between Indian Basmati and Egyptian Giza rice flour dispersions as influenced by particle size

“…The possible reason for such an abrupt increase in fat content in the finest particles could be attributed by exposure of more surface area to solvent during extraction process. A similar increase in fat content during size reduction of corn and cowpeas has been reported (Kerr, Ward, McWatters, & Resurreccion, 2000;McGhee, Black, & Brekke, 1974). McGhee et al (1974) reported degree of fat removal increased with fineness of ground and mostly 40e50% more fat was extracted when the grits were finely ground to 42-mm from 420-mm.…”

A study on starch profile of rajma bean ( Phaseolus vulgaris ) incorporated noodle dough and its functional characteristics

“…In the present study, results of particle size can be correlated by increase in water absorption in Farinograph. This also has an effect on product quality with change in water absorption and dough development (Kerr, Ward, McWatters, & Resurreccion, 2000).…”