OPTIMIZATION OF HEXAMETAPHOSPHATE-ASSISTED EXTRACTION OF FLAXSEED PROTEINS USING RESPONSE-SURFACE METHODOLOGY

Total proteins of defatted law-mucilage flaxseed meals were isolated b y extraction with aqueous sodium hexametaphosphate (SHMP). A composite central rotatable design was used to study effects of pH (X(1)), meal -to-solvent ratio (X(2)) and concentration of SHMP (X(3)) on nitrogen extractability (Y-1) and protein recovery (Y-2). Using RSM, quadratic polynomial equations were obtained for Y, and YI by multiple regressio n analysis. All three variables significantly affected nitrogen solubi lity and protein extractability. The pH was the most effective factor and meal-to-solvent ratio was least. Verification experiments confirme d validity of predicted models. Stationary points fur response surface s were characterized as maxima and they were Y-1=77.6% at X(1)=8.90, X (2)=1:33.6 and X(3)=2.75% and Y-2=57.5%6 at X(1)=9.00, X(2)=1:33.3 ant i X(3)=2.85%, for nitrogen extractability and protein recovery, respec tively.