Extraction of protein from the macroalga Palmaria palmata

The effect of NaOH and N-acetyl-L-cysteine (NAC) concentration, mass:volume, agitation and extraction temperature on the recovery of alkaline soluble proteins from milled oven-dried Palmaria palmata was studied. The contribution of physical (osmotic shock and shearing) along with enzymatic cell disruption approaches on the extraction of aqueous and alkaline soluble proteins was also assessed. Optimal alkaline soluble protein extraction occurred when using 0.12 mol/l NaOH. 0.1 g/100 ml NAC, a mass to volume ratio of 1:15 (w/v) and when stirring for 1 h at room temperature. The concentration of NaOH and NAC employed were the critical parameters associated with extraction of the alkaline soluble protein. Cell disruption using osmotic shock and high shear treatments resulted in mean alkaline soluble protein recovery of 5.76 and 6.18 g/100 g dry weight, respectively. Prior treatment of macroalgal cells with the food-grade polysaccharidase preparations, Celluclast (R) 1.5L and Shearzyme (R) 500L, resulted in a mean alkaline soluble protein recovery of 8.39 g/100 g dry weight. However, due to the high enzyme:substrate required, the application of these polysaccharidases may not be feasible for the extraction of intact P. palmata proteins. The results presented herein are relevant to the extraction of intact protein fractions from seaweed sources. (C) 2012 Elsevier Ltd. All rights reserved.