Variation in oligosaccharide profiles observed with AP-MALDI in different regions of maize kernels after treatment with xylanases

Abstract: In wet-milling of maize, an approach to obtain a more efficient extraction of starch is to use enzymes to degrade cell-wall polysaccharides that encapsulates the starch granules. To enhance the understanding of how these enzymes function in the maize kernel, mass spectrometry imaging was used to compare the oligosaccharide degradation products formed and their distribution in maize kernels after treatment with three xylanases. For the measurements, amylase treated cryosections of maize kernels were sprayed with different xylanases on approx. one half of the surface area and then incubated for 17 h. Mass spectrometry images were then generated using an atmospheric pressure MALDI-MSI system. The images show the distributions of a wide variety of oligosaccharides and the enzyme ability to produce these oligosaccharides in distinct locations of the maize kernels. The approach provides new information on how the efficiency of xylanase to form specific degradations products are dependent on the morphological regions of maize kernels. It also provides indirect information about possible changes in the constituents of the arabinoxylan substrate by showing the distributions of oligosaccharides with various decorations of the xylan backbone.