Effective Soybean Oil Degumming by Immobilized Phospholipases A₂ from Walterinnesia aegyptia Venom

Abstract

Enzymatic degumming utilizing phospholipase enzymes could be used in ecologically friendly procedures with enhanced oil recovery yields. In this study, two phospholipases A 2 of group I and II, WaPLA 2 -I and WaPLA 2 -II, from the snake venom of Saudi Walterinnesia aegyptia were evaluated for soybean oil degumming after being immobilized on three different support materials (calcium alginate (CA), CA-gelatin (CAG), and CA-chitosan (CAC), and cross-linked with glutaraldehyde). Higher yields of CAC-immobilized PLA 2 -I (85 ± 3%) and PLA 2 -II (87 ± 3.6%) compared to CAG (77.3 ± 2.1 and 79 ± 2.6%, respectively) and CA beads (55.7 ± 2.5% and 57.3 ± 3.1%, respectively) were observed. In addition, the optimal temperature of immobilized WaPLA 2 -I and WaPLA 2 -II increased from 45 to 55 °C and from 55 to 65 °C, respectively. Their stability at high temperatures was also significantly enhanced covering a larger range (70−80 °C). Likewise, the pH/activity profile of WaPLA 2 was greatly expanded upon immobilization with the pH-optima being shifted by 0.5 to 1 pH unit to the basic side. Similarly, the stability of WaPLA 2 s in the presence of organic solvents was also significantly improved, while the affinity for calcium and bile salt was the same for both free and immobilized enzymes. Interestingly, the remaining activity of immobilized WaPLA 2 onto different supports was more than 50 or 60% after eight recycles or 120 days of storage at 4 °C, respectively. CAC−WaPLA 2 -II was the best immobilized enzyme complex for the oil degumming process by reducing its final residual phosphorus content from 168 mg/kg to less than 10 mg/kg in only 4 h. Overall, CAC− WaPLA 2 -II showed the most attractive profiles of temperature, pH, and reaction duration as well as significant storage stability and reusability.