Effect of particle size, flour:water ratio and type of pulse on the physicochemical and functional properties of wet protein extraction

Background and Objectives Extraction of proteins by alkaline extraction followed by isoelectric precipitation at three different flour: water (f:w) ratios (1:10, 1:7, and 1:5) were investigated for four pulse flours: yellow pea (YP), green lentil (GL), kabuli chickpea (CH), and navy bean (NB). Pulse flours were prepared by pre‐breaking the seeds and milling into flour using a Ferkar (knife) mill with either a 0.5 mm (P1) or 1.27 mm (P2) screen. Surface properties and functionality of the protein concentrates were evaluated. Findings Extraction yields showed no major differences between the investigated f:w ratios. Protein yields decreased significantly as the amount of water decreased. The 1:10 f:w ratio was selected to perform extractions with coarser flours (1.27 mm; P2). Results showed that flour with a smaller particle size increased yields by 0.4% to 3.2% for extraction, and 7.9%–10.3% for protein. Functional properties showed no major differences between proteins extracted at different f:w ratios, although differences were found between the different pulse types. In some cases, P2 and P1 concentrates differed in functional properties, but this was not consistent for all pulses. Conclusions Finer flour (P1) and higher f:w ratio (1:10) resulted in higher extraction and protein yields. Significance and Novelty This study highlights the importance of milling and control of the particle size of the flours and water use on the preparation of protein concentrates.