Determination of resistant short-chain carbohydrates (non-digestible oligosaccharides) using gas–liquid chromatography

We have proposed the term short-chain carbohydrates (SCC) for those species, other than the free sugars, that are soluble in 80% ethanol under well-defined conditions. We describe a technique for the measurement of resistant SCC (RSCC), which are not susceptible to pancreatic amylase or the brush border enzymes and therefore sometimes termed non-digestible oligosaccharides. In the procedure, alpha-glucans (starch and maltodextrins) are hydrolysed enzymatically to glucose and the non-starch polysaccharides (NSP) are precipitated in ethanol. Fructans are hydrolysed enzymatically and the monosaccharide constituents are reduced to acid-stable alditol derivatives before the remaining RSCC are hydrolysed with sulphuric acid. All the constituent sugars are measured as alditol acetate derivatives by gas–liquid chromatography. The protocol allows both the measurement of total RSCC and a separate, specific measurement of fructans.