Porcine in vitro digestion and matrix structure of undigested residue of xylanase- and cellulase-supplemented maize and wheat

Abstract

Background

This study investigated the effects of supplementing maize and wheat with a combination of xylanase and cellulase on porcine in vitro digestibility, nonstarch polysaccharides (NSP) solubilization, and matrix structure. The latter was assessed using synchrotron-based micro-computed tomography (SR-μCT) and Fourier transform mid-infrared (FTMIR) spectroscopy after porcine in vitro degradation. Cereal grains were subjected to porcine in vitro digestion with or without enzyme supplementation (20 000 U kg⁻¹ of each enzyme) in a 2 × 2 factorial design.

Results

In vitro dry matter digestibility (IVDDM) was lower for maize than for wheat (P < 0.05), and enzyme supplementation had no effect on IVDDM. Supplemental enzymes reduced arabinoxylan content in the undigested residue of wheat (53 vs 46 g kg⁻¹, P < 0.05) but not maize (42 vs 44 g kg⁻¹; P > 0.05). Synchrotron-based micro-computed tomography imaging revealed aleurone cells with intact content in the undigested residue of both maize and wheat, regardless of enzyme supplementation. Some endosperm cells in undigested maize residue retained their content, whereas nearly all endosperm cells in undigested enzyme-unsupplemented wheat residue were empty. No endosperm cells were detected in undigested enzyme-supplemented wheat residue. Fourier transform mid-infrared imaging indicated a higher presence of phenolic compounds in maize cell walls than in wheat.

Conclusion

Supplemental enzymes did not affect IVDDM for wheat, as they primarily degraded endosperm cell walls, the content of which was already released by pepsin and pancreatin digestion. Similarly, IVDDM for maize remained unaffected, which was probably due to the high phenolic content of its cell walls. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.