Fig 1

Priyanka Kumar

and 5 more

The Chilean granado bean (Phaseolus vulgaris L.) contains nutritionally valuable proteins, and there was indication that the proteins can help in the prevention of diabetes. To further explore tis potential purified samples of the bean proteins is required. A membrane-based process was developed for the isolation of proteins from granado beans, adapted from methods reported earlier for mustard protein processing. The optimised process consists of alkaline protein extraction from granado bean flour at pH 10, ultrafiltration at concentration factor 4 and diafiltration with diavolume 4 followed by isoelectric protein precipitation at pH 4. The process starting with granado beans containing 28% protein, recovered 60.1% of the protein as precipitated protein isolate (PPI) and 7.2% as acid soluble protein isolates (SPI). The losses in the process system were approximately 26% of mass and 18.8% of nitrogen due to removal of non-protein nitrogen and small molecular weight components, likely carbohydrates. The protein contents of the PPI and SPI were ~92 % and ~ 62% on a moisture-free basis; the protein content of the SPI produced is considerably lower than typical isolates. This may be due to the co-recovery of high molecular weight carbohydrates. The water absorption capacity and nitrogen solubility index, of the PPI and SPI were measured and compared to other oilseed isolates. The PPI showed high water absorption (<400%). SPI dissolved completely – a nitrogen solubility index of 100%, while PPI had low nitrogen solubility near its isoelectric point. Both isolates had traits desirable for easy incorporation into food products.