An innovative two-step enzymatic membrane bioreactor approach for the continuous production of antioxidative casein hydrolysates with reduced bitterness

Enzymatic batch processes bear some disadvantages, such as the high quantity of enzyme, energy and labor needed and, consequently, high production costs. The aim of this study was the production of a sodium caseinate hydrolysate with improved antioxidative capacity and reduced bitterness in a continuous system to avoid such drawbacks. Therefore, a novel, food-grade, two-step enzymatic membrane bioreactor (EMBR) process was designed in which a functional improved permeate with a 33% increased antioxidativity compared to sodium caseinate was produced with the endopeptidases Sternzym BP 25201. This bitter permeate was subsequently debittered in a second EMBR step with commercial Flavourzyme, which was reduced in its endopeptidase activity. This resulted in a linear production of 7.5 gProduct h−1 of antioxidative (antioxidativity: +39% compared to sodium caseinate), debittered peptides. The influence of the peptidases on each other was excluded by separating the endo- and exopeptidases in two EMBR steps and a product with consistent properties like degree of hydrolysis, antioxidativity and taste was obtained. The process conditions chosen were optimal regarding a stable product formation for three days. Therefore, the process was superior in its productivity, enzyme usage and run time compared to an equivalent batch process.