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BSTRACT: Soybean protein concentrates were produced by ultrafiltration with a commercial 4-in spiral wound module with a polyvinylidene difluoride membrane. With soy flour suspensions of 2% total solids (TS), protein content could be increased from 50% (dry basis) to 67% by ultrafiltration and/or diafiltration. Soluble sugars could be removed almost completely, but ash content of retentate solids did not decrease significantly. Higher protein contents would require removal of some of the fiber and/or manipulation of the feed environment to reduce solute-solute interactions. Protein yields were 90%. Flux decreased from 78 L/m2/h (LMH) with 2% TS soy flour suspension to 22 LMH at 17% TS. [ABSTRACT FROM AUTHOR]

Extracts of defatted soybean flour were processed in polymeric spiral wound and tubular ultrafiltration modules to produce soy protein concentrates. Soy flour suspensions displayed low fouling tendencies with either module when operated at pressures of 235kPa (35psi) or less. With soy flour suspension of 2% total solids (TS) at 50°C, flux with the spiral module showed asymptotic behavior above 235kPa, reaching a plateau value of 80liters per square meter per hour (LMH) at a pressure drop of 69kPa, equivalent to a cross-flow of 170l per minute. Flux decreased to 55 LMH at 5% TS and to 22 LMH at 17% TS under these operating conditions. With the tubular module processing 5% soy flour, flux became pressure-independent at 385kPa (55psi) at cross-flow velocities of 0.5 and 1.5ms-1. Asymptotic fluxes at these velocities were 19 and 44 LMH, respectively. However, at 2.5ms-1, flux increased with pressure to 85 LMH at 490kPa (70psi). The tubular module flux decreased to 55 LMH at 7% TS and to 24 LMH at 21.6% TS. Flux could be modelled with the film theory mass transfer model and the resistance-in-series model. [Copyright &y& Elsevier]