Hybrid bipolar membrane electrodialysis/ultrafiltration technology assisted by a pulsed electric field for casein production
Electrodialysis with bipolar membranes (EDBM) is an ecofriendly technology providing a wide spectrum of solutions for modern industry. The main advantage of EDBM is the absence of chemicals during the treatment, which makes it very attractive especially in the food and pharmaceutical sectors. The production of casein, the major milk protein, by means of EDBM is a very interesting approach in the sustainable development context due to the high product purity, no waste generation and the absence of hazardous reagents. Casein is widely used as a food additive in order to improve the food nutritional value as well as to create the desirable functional properties. Moreover, casein is a source of bioactive peptides having beneficial effects on human health. However, the major obstacle hampering the industrial application of EDBM for the production of casein with improved quality is precipitation of casein inside the EDBM stack and membrane scaling. Here we propose a hybrid technology comprising an EDBM module coupled with an ultrafiltration (UF) module. Our results show that the use of the UF module prior to EDBM allows complete prevention of casein precipitation inside the EDBM stack which plays a crucial role in the improvement of EDBM efficiency. In addition, we have found that electroacidification may be performed until pH 5.0 instead of the conventional value of 4.6, which allows a substantial decrease in membrane scaling. Finally, application of pulsed electric field mode allows inhibition of scale formation and OH− leakage, which hastens the EDBM process and increases the membrane lifetime.