Birgir Norddahl
Associate Professor
University of Southern Denmark

Birgir Norddahl is a native of Iceland, graduating from Aarhus University, Denmark with a degree in both chemistry and nuclear physics. Birgir has more than 20 years’ experience in the polymer industry, biotechnology and membrane technology applications in various fields before re-entering university as an associate professor at the University of Southern Denmark specializing in membrane technology and biotechnology with regard to application of algae and plants as nutraceuticals and dietary supplements.

Membrane Bioreactor for Enzymatic Hydrolysis of Pectin and Cellulose in Berry Promace for the Release of Antioxidants

Antioxidants from living organisms are attracting a lot of interest for their use as nutraceuticals and as natural colours in food. Pomace, which is the residual after producing juice from berries, is currently considered a waste of no value, but often contain the main part of the polyphenols from the berries, constituting the colour of the berry. These polyphenols are normally bound to the epidermal cells of berry skin, which is made up of pectin and cellulose moieties. When extracting the polyphenols from the pomace the yield of the extraction is often rather low compared to the total amount of phenols present, but enzymatic treatment of the pomace during extraction with pectinases and cellulases can increase the yield. It is known that pectinases and cellulases are inhibited by sugars produced from the enzymatic hydrolysis and polyphenols in solution in the extracting liquid, but the use of a UF membrane connected to the bioreactor, where the extraction takes place, allows passage of sugars and polyphenols lowering the concentration of these compounds in the extraction volume, while at the same time retains the enzymes in the vessel and ensures a lower degree of inhibition of the enzymes, which enables a higher degree of hydrolysis and yield of the extraction to be obtained. In this project pomace from production of aronia juice is the object of extraction in a membrane bioreactor (MBR) and the experiments performed have shown a much higher yield of polyphenols in an extraction than in a traditional extraction. Another benefit from the use of an MBR is that the permeate from the process is a cleared liquid not containing any suspended solids, which is normally only removed as a result of elaborate unit operations. Performance of the MBR with different membranes and operational parameters like temperature, type of enzymes, cross flow velocities and pressure are reported in the final presentation.