Optimization of an enzymatic wheat gluten hydrolysis process in an enzyme membrane reactor using a design of experiment approach

The aim of this study was to determine the optimal conditions for operating an enzyme membrane reactor system to obtain a high yield of amino acids and peptides released from wheat gluten with Flavourzyme™. The optimal operating conditions were determined using multivariate analysis. A fractional factorial design made up of 27 runs amended by eight axial points was followed in a bench-scale enzyme membrane reactor system (V = 2 L), and responses were recorded over 8 h. Optimal conditions determined were a temperature of 50 ± 1 °C and a Flavourzyme™ activity of 116 ± 4 nkatLeu-pNA/mL. Modeling resulted in an optimal substrate feed rate of 19.2 g/L/h and a permeate flux of 57 L/m2/h. The enzymatic wheat gluten hydrolysis in an enzyme membrane reactor was conducted for 72 h with an average total product space–time yield of 12.6 ± 1.3 g/L/h (n = 4) and a free amino groups space–time yield of 4.4 ± 0.4 g/L/h (n = 4), and the substrate utilization was 0.82 ± 0.01 (g/g) (n = 4). The resulting product–enzyme ratios were 7.7 ± 0.6 mgTP/nkatLeu-pNA (n = 4) and 3.0 ± 0.2 mgFAA/nkatLeu-pNA (n = 4). The productivity of the enzyme membrane reactor improved compared to the reference batch process and doubled compared to previously proposed enzyme membrane reactor processes for the hydrolysis of wheat gluten.