Research on prebiotics and other novel health-promoting food components has been active for over a decade. Arabinoxylan (AX) derived arabinoxylooligosaccharides (AXOS), which may have various chemical structures, depending on the xylan source and the degradation method used, stand increasingly in the spotlight as potential prebiotics. During the past decade, the studies of the possibilities to produce the AXOS by using biocatalytic conversion have received more attention. In addition, there is an interest in the use of novel cereal biomass for the production of AXOS. The aim of this study was to investigate the influence of various commercial enzyme preparations on the degradability of insoluble arabinoxylans in wheat and rye wholemeal treated by extrusion, identify and quantify xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS) in treated media. The enzymatic degradation of rye and wheat cell wall materials was monitored by HPSEC, HPAEC and MALDI-TOF-MS techniques. It was noticed that there is no significant difference between extruded and natural cereals, and type of cereals had not significant influence on XOS and AXOS production. The most effective biocatalysts were hemicellulases expressed in the enzyme preparations from Trichoderma and Aspergillus spp. (Depol 692), Humicola and Bacillus spp. (Ceremix Plus). Degradability of rye and wheat cell wall materials by these enzyme preparations obtained break down percentages of 70-87% and 67-77%, respectively. After enzymatic treatment, only small amounts of xylose, xylobiose, and xylotriose was eluted compare to the amount of more complex oligosaccharides with higher degree of polymerization (DP). The mass spectra of oligosaccharides indicated the presence of a homologous series of pentoses ranging from DP 4 to 15. This indicates that chosen enzyme preparations acted well on wheat and rye biomass, and released quite high amounts of XOS and AXOS. (C) 2012 Elsevier B. V. All rights reserved.