Isolation of clean-label faba bean (Vicia faba L.) proteins: A comparative study of mild fractionation methods against traditional technologies

Plant protein isolation by mild wet processing methods that are free of alkali/acid and thermal treatments were investigated in order to address the fast growing consumer demand for clean-label ingredients. The impact of different mild wet fractionation conditions was established in terms of yield, purity and recovery of faba bean protein concentrates/isolates (PCs/PIs) from both Snowbird (low tannin, LT) and Athena (high tannin, HT) cultivars. Although salt-soluble globulins (74 to 75%) were the primary proteins found in faba beans, PIs resulting from dialysis (LT: 93.2 +/- 0.1% and HT: 96.4 +/- 0.3%) or micellization (LT: 99.1 +/- 0.1% and HT: 98.7 +/- 0.2%) following water extraction at 35 degrees C (W35) at a solvent/feed (S/F) ratio of 2 had higher protein contents than PCs from aqueous NaCl extraction followed by dialysis (LT: 79.1 +/- 0.1% and HT: 81.6 +/- 0.5%) or alkali extraction followed by acid precipitation (LT: 87.1 +/- 1.4% and HT: 86.3 +/- 0.2%). These differences in protein extractability of water-and salt-based methods could be attributed to the high levels of endogenously present minerals. Although methionine and cysteine were limiting amino acids, the W35 methods resulted in overall higher amino acid content and in high-quality PIs compared to the rest due to the presence of albumins as confirmed by SDS-PAGE. The W35-PIs were low in raffinose family oligosaccharides, tannins and trypsin inhibitory activity and can be considered chemical-free alternatives to alkali extracted-acid precipitated PCs.