Studies on the mode of action of non‐starch‐polysaccharides (NSP) degrading enzymes in vitro

Abstract

An in vitro model using the model substance wheat bran as NSP source was developed to study the effects of NSP degrading enzymes (xylanase and β3‐glucanase) on NSP fractions. The in vitro model simulates the conditions (pH, dry matter, temperature and transit time) in the fore sections of the porcine gastrointestinal tract. By neglecting endogenous enzymes the sole effect of the added enzymes could be investigated. By application of the enzyme complex, a significant degradation of the insoluble NSP fraction was observed in all sections of the porcine gastro‐intestinal tract simulated by the in vitro model. A strong dose dependent effect was determined. Compared to the control, the arabinose/xylose‐ratio generally increased but differences were found between the sections simulated. Considering the arabinoxylans in the soluble NSP fraction, the effect of enzyme supplementation was reflected by a change in the arabinose and xylose contents. In comparison to the control, an increase in the amounts of arabinose and xylose was observed at low enzyme doses applied. However, with increasing enzyme activities the amount of arabinose and xylose declined. The in vitro model is considered as a useful tool for preliminary tests to estimate the effects of NSP‐degrading enzymes on NSP fractions in the fore sections of the porcine gastro‐intestinal tract.