Fileting processes in the fish industry receives fish of food grade,and if treated hygienically, by-products are valuable sources ofmarine oil and proteins which could be used for human consump-tion. A potential increase in the use of fish by-products for the∗Corresponding author. Tel.: +47 98 24 50 33; fax: +47 93 27 07 01.E-mail address: rasa.slizyte@sintef.no (R.ˇSliˇzyt˙e).production of valuable and active ingredients, gives a good futureperspective for the marine biotechnology industry [4]. In orderto achieve successful industrial implementation of processes forextraction of purified marine ingredients, two main challengesshould be overcome: (1) documentation and verification of healthclaims should be available and (2) good sensory quality, stabilityand uniformity of the products must be ensured [4]. During the lastdecades much has been done both on scientific investigation andindustrial implementation for better utilization of fish by-products[4–8]. However, only a few scientific articles deal with furtherprocessing of herring by-products, with the focus being processingof herring oil [9–13]. The protein-containing fractions make up asignificant part after oil extraction and are mostly used for animalfeed, but can potentially be considered as more valuable productsfrom processing of herring by-products [14–16].