Combined effect of operational variables and enzyme activity on aqueous enzymatic extraction of oil and protein from soybean

The individual effect of two different enzymes-protease and cellulase-on oi l and protein extraction yields combined with other process parameters-enzy me concentration, time of hydrolysis, particle size and solid-to-liquid rat io-was evaluated by Response Surface Methodology. The selection of the enzy mes for the study was based on preliminary experiments that showed higher i ncrements in the extraction yield with the use of the two enzymes when comp ared to hemicellulase and pectinase. The levels of the quantitative paramet ers studied were: i) enzyme concentration: 0.1, 0.45, 2 w/w %; ii) liquid-t o-solid ratio: 0.05, 0.125, 0.2; iii) mean particle size: 212.5, 449.5, 855 mum; iv) time of hydrolysis: 30; 60; 120 min. Experimental data for both o il and protein extraction yields obtained with and without enzymes correlat ed very well with process parameters (P < 0.0001), resulting in models with high coefficient of determination for oil and protein extraction yields (r (2) = 0.9570 and r(2) = 0.9807, respectively). The use of protease resulted in significantly higher yields over the control (protein yield increased f rom 27.8 to 66.2%, ail yield increased from 41.8 to 58.7%) only when heat t reated flour was used, or when non-heat treated hour with large particle si zes was used in the extraction. The yields of protein and oil from non-heat treated material in general decreased slightly with the use of enzymes. (C ) 2001 Published by Elsevier Science Inc.