Inspire forum highlights complex nature of plant NSPs

The inaugural Inspire: Non-starch Polysaccharide (NSP) Forum got underway March 31 with 80 delegates from 23 countries hearing presentations aimed at generating a deeper understanding of the complex structures of plant NSPs and the factors that influence their nutritional impact. It was the first of three sessions across the three days of the Inspire forum looking, respectively, at aspects of the NSP substrate, the impact of fibre on animal nutrition and feed enzyme solutions to improve efficacy and sustainability.
Chairing this first session, AB Vista Research Director Mike Bedford highlighted the importance of understanding how NSPs were synthesised and structured when the target was to achieve effective and targeted breakdown using exogenous enzymes.
The process by which cellulose is synthesised was outlined by Dr. Staffan Persson of the Max Planck Institute. This was followed by a review of the arabinoxylan structure of cereal grains using a fluorescently-labelled inactivated xylanase by Joran Verspeet of KU Leuven, a technique which also highlighted clear evidence of specificity between different xylanases and different arabionoxylan structures.
Stan Cauvain of Baketran then discussed the experience of the breadmaking industry in using xylanases to overcome the water retaining ability of grain NSPs to maintain bread quality. It was problem that had grown considerably as demand for high fibre wholemeal bread increased during the past 30 years.
Cauvain stated: "The problem is that we have very little idea of why xylanase works in breadmaking. We know how to control the results, but we don't know exactly what is happening in terms of the interaction between the enzyme and grain quality."
Cauvain also highlighted the enormous challenge faced by his industry due to the variability in fibre content between flour batches, between flour types and between growing seasons. The inability to reliably predict response to xylanase addition - or the effect of the xylanase inhibitors known to be present in some grains - meant a heavy reliance on extensive and regular trial and error screening, a situation with considerable parallels in the feed industry.
The session closed with a presentation by Per Aman of the Swedish University of Agricultural Science, who discussed the challenges faced when trying to analyse plant fibre.
"None of the methodologies currently used produce exactly the same substrate conditions as found in the animal gut," he stated. "In terms of the characteristics important to animal nutrition, the molecular structure of the fibre component can be hugely important, as can agronomic conditions.
"For example, the branching on the xylose backbone of arabinoxylan molecules dictates the extent of viscosity effects, as well as how and where xylanases can act to break down those long-chain molecules. Differences between growing sites can also exceed varietal differences, and a detailed knowledge of these factors is essential when looking to understand xylanase activity."