The high fiber content of cereal
coproducts used in animal feed
reduces the digestibility and nutrient availability. Therefore, the
aim of this study was to elucidate the ability of two carbohydrase complexes to degrade the cell
wall of wheat, maize, and rice during in vitro digestion.
One complex was rich in cell-wall-degrading enzymes (NSPase 1), and
the other was similar but additionally enriched with xylanases and
arabinofuranosidases (NSPase 2). Degradation of arabinoxylan, the
main cereal cell wall polysaccharide, was followed directly by gas–liquid
chromatography (GLC) and indirectly through phenolic acid liberation
as quantified by liquid chromatography–tandem mass spectrometry
(LC–MS/MS). The effect was additionally visualized using a
unique multispectral autofluorescence approach. Wheat fractions, in
particular aleurone, were susceptible to degradation as judged from
the redistribution of arabinoxylan (25% reduction in insoluble arabinoxylan),
whereas the highest relative liberation of ferulic acid was observed
in rice bran (6%). All cereal fractions, except for maize, had a higher
release of ferulic acid with NSPase 2 than NSPase 1 (38% in rice and
wheat bran, 30% in wheat whole grain, and 28% in wheat aleurone).
Thus, the carbohydrase complexes were able to degrade important cell
wall components during in vitro digestion but apparently
through different mechanisms in wheat, maize, and rice.