Development of an ultrafiltration process for the purification of sunflower albumins

• UF/DF process developed to purify SFA with 94.6% protein purity. • Suitable membrane conditions were identified (5 kDa, TMP 1.5 bar). • Phytic acid content reduced by 95%, overcoming major purification challenge. • SFA isolate showed emulsifying capacity of 44% an a suitable white color suitable for food applications In this study, the ultrafiltration/diafiltration (UF/DF) purification process was carefully developed to produce sunflower albumins (SFA) isolate. Process conditions were selected based on the retention rate of SFA and elimination rate of undesirable compounds such as chlorogenic acid (5-CQA), phytic acid and total sugars. A challenge in developing this process was achieving a balance between the SFA recovery and effectively removing phytic acid. The suitable conditions for the UF/DF process were 5 kDa cut-off and 1.5 bar of transmembrane pressure (TMP). The process involved 3 diafiltration volumes (DV) of NaCl 0.25 M followed by 3 DV of water. It yielded a SFA retention rate of 96.9 ± 0.36% and up to 90% removal of undesirable compounds. A pilot laboratory scale process was implemented, including a pre-concentration step by UF with a volumetric concentration factor (VCF) of 5 to reduce water consumption during UF/DF. This resulted in a protein yield process of 68% and over 95% removal of phytic acid, 5-CQA, and total sugars. The productive permeate flow was 6 µm·s -1 for the first 3 DV and 4 µm.s -1 for the last 3 DV. The NaCl concentration was reduced from 0.16 M to 0.01 M. The SFA isolate had a suitable white color, high protein purity (94.6%), and low content of phytic acid (2.4%), 5-CQA (0.0%), and total sugars (2.3%). Its solubility ranged from 95 to 98% in a pH range of 3 to 9. Additionally, SFA isolate displayed good emulsifying properties, with an emulsifying capacity of 44% and stability of 93%.