Submitted to: Food Technologists Institute
Publication Type: Abstract Only
Publication Acceptance Date: 6/24/1998
Publication Date: N/A
Technical Abstract: A plate and frame ultra filtration system with three flat sequential membranes (molecular weight cutoff range: 50-100 KD, 15-30 KD, and 5-10 KD, membrane area approximately 0.863 m**2) was used to evaluate the separation and functional characteristics of an aqueous alkaline cowpea protein extract. The flux (L/h) and permeation rates (L/h/m**2) of the retentate (CPR) and three permeates (CPP1, 2 and 3) were measured during a 6 hr batch process. Protein content, recovery, molecular weight characterization and functional properties of freeze dried samples were compared to a commercial soy protein isolate (SPI). Flux and permeation rates ranged from 045 - 3.54 L/h and 0.18 - 4.03 L/h/m**2, respectively, Protein content of the fractions ranged from 18-53 %. Recoveries, based on the aqueous extract, were 84% in the CPR, and 7.49+%, 3.63% and 0.67% in CPP1, 2 and 3 respectively. SDS PAGE of the protein fractions indicated ban patterns in the range of 6.5-66 KD for COR, 29-32 KD for CPP1, 14.5 - 29 KD for CPP2 and 14 KD for CPP3. The hydration properties of the CPR showed higher water absorption and lower nitrogen water solubility index compared to the SPI. Emulsification and Foaming capacities were lower but more stable for CPR than for SPI. Gelation characteristics indicated similar critical gelation concentrations, but lower gel strengths for the CPR than for the SPI. The plate and frame ultra filtration membrane system employed provided discrete protein factions with native functional properties.