Establishment of an Enzymatic Membrane Reactor for Angiotensin-Converting Enzyme Inhibitory Peptides Preparation from Wheat Germ Protein Isolates

In this paper, an efficient enzymatic membrane reactor (EMR) was established for the preparation of angiotensin-converting enzyme (ACE) inhibitory peptides from wheat germ protein isolates (WGPI). It promoted the protein conversion and improved the enzyme utilization rate. ACE inhibitory peptides of WGPI were prepared using 5 kDa membrane device for enzyme membrane coupling. Based on the results of the protease activity preservation experiment, substrate intercept experiment, batch EMR experiment and continuous EMR experiment, the conditions of EMR were decided as follows: substrate concentration of 1.2% (w/v), alcalase quantity of 110 μL, temperature of 50C, pH of 9.0, effective volume of 0.4 L, permeation flux of 0.005 L/min and turn into 0.011 L/min after 10 min and runtime of 300 min. The continuous EMR method showed high conversion rate of protein (55.3%) and IC50 of peptides (0.50 mg/mL). The conversion rate of protein significantly increased by 36.17% and the IC50 of peptides significantly reduced by 30.6% compared with the traditional enzymatic hydrolysis method. Therefore, the continuous EMR is beneficial to the efficient production of ACE inhibitory peptides from WGPI. Practical Applications Using food protein as raw material, functional polypeptides products have been developed by employing enzymatic hydrolysis and series of high technologies. However, during the preparation of functional polypeptides, some problems of low reaction efficiency, product yield and product activity existed, which seriously influence the performance of technology industrialization. The enzymatic membrane reactor (EMR) is an effective mode which can achieve continuous operation by the integration of substrate enzymolysis, enzyme recovery and hydrolyzate separation in functional polypeptides producing. Utilization of the EMR technology will not only increase food protein commercial value, but will also satisfy the needs of the polypeptide processing industries for efficient, low-cost producing.