Immobilization of Phospholipase A₁ and its Application in Soybean Oil Degumming

Abstract

Abstract Phospholipase A 1 (PLA 1 ), or Lecitase ® Ultra, was immobilized on three different supports, calcium alginate (CA), calcium alginate‐chitosan (CAC), and calcium alginate‐gelatin (CAG), and crosslinked with glutaraldehyde. The results indicated that PLA 1 –CA retained 56.2% of the enzyme's initial activity, whereas PLA 1 –CAC and PLA 1 –CAG retained 65.5 and 60.2%, respectively. Compared with free PLA 1 , the optimal pH of immobilized PLA 1 shifted to the basic side by 0.5–1.0 pH units and the pH/activity profile range was considerably broadened. Similarly, the temperature‐optima of PLA 1 –CAC and PLA 1 –CAG increased from 50 to 60 °C, and their thermal stability increased with relative activities of more than 90% that covered a wider temperature range spanning 50–65 °C. In a batch oil degumming process, the final residual phosphorus content was reduced to less than 10 mg/kg with free PLA 1 , PLA 1 –CAC and PLA 1 –CA in less than 5, 6 and 8 h respectively while PLA 1 –CAG was only able to reduce it to 15 mg/kg in 10 h. When the PLA 1 –CAC was applied in a plant degumming trial, the final residual phosphorus content was reduced to 9.7 mg/kg with 99.1% recovery of soybean oil. The recoveries of immobilized PLA 1 –CAC and activity of PLA 1 were 80.2 and 78.2% respectively. Therefore, it was concluded that PLA 1 –CAC was the best immobilized enzyme complex for the continuous hydrolysis of phospholipids in crude vegetable oils.