Particle size distribution, cowpea

Three screen sizes (2.0, 1.0, 0.5 mm) were used for milling cowpeas and produced the particle size distributions shown in Figure 8. With the 2.0 mm screen, particles were concentrated (76%) in the 30-100 mesh range. With the 1.0 mm screen, most of the particles (82%) were in the 50-200 mesh range. Eighty per cent of the particles were in the 200-400 mesh range with the 0.5 mm screen. 

In preparing akara from each milled product, too many large particles still remained in the 2 mm material to make a smooth paste. However, highly acceptable akara with uniform shape was produced from this material after the paste was ground to eliminate the large particles. With the 0.5 mm screen, the paste was very fluid and extremely difficult to dispense, behavior which closely resembled that exhibited by the commercial cowpea flour. Akara prepared from the 0.5 mm material was also extremely distorted. Of the three screen sizes compared, the 1.0 mm screen produced the most desirable particle size distribution although the paste produced from the 1.0 mm material was somewhat more fluid than desired, it appeared that adjustments could be made in hydration of the meal to achieve an appropriate batter viscosity. 

Figure 7. Particle size distribution of traditionally processed cowpea paste and mechanically milled cowpea flour. Reproduced with permission from Ref. 9. Copyright 1983, American Association of Cereal Chemists.

Singh, A., Hung, Y. C., Philhps, R. D., Chinnan, M. S., and McWatters, K. H. (2004). Particle-size distribution of cowpea flours affects quahty of akara (fried cowpea paste). Journal of Food Science, 69(7), 243-249. 

Interestingly, nanopartide assembly to form oil-water emulsions can also be performed using nanoparticles obtained from nature, such as vims particles, or more generally protdn-based nanocages referred to as hionanopartides. Such partides are of similar size to many s)mthetic nanopartides and nanorods, yet differ in that their size distribution is uniform, and their ligands consist of the surface-available amino add fimctionality. Examples of bionanopartides that have been reported in oil-water interfacial assemblies indude TMV, cowpea mosaic vims (CPMV), turnip yellow mosaic vims (TYMV), and horse spleen ferritin (HSF). ... 

---