Evaluation of fructans in various fresh and stewed fruits by high-performance anion-exchange chromatography with pulsed amperometric detection

Fructans are food-grade non-digestible carbohydrates that exert beneficial nutritional effects. Their characterization and quantification is required for food-labeling purposes. We describe the suitability of high-performance anion-exchange chromatography coupled with pulsed amperometric detection f or the identification and quantification of fructans in fresh fruits (vario us apple and pear cultivars, plum, banana) as well as in commercial stewed fruits obtained from a local manufacturer. After extraction with water and appropriate filtration, inulobiose [beta -D-Fru-(2 -->1)-beta -o-fructofura noside; F2], 1-kestose [beta -D-Fru-(2 -->1)(2)-alpha -D-glucopyranoside; G F2] and nystose [beta -D-Fru-(2 -->1)(3)-alpha -D-glucopyranoside; GF3] wer e completely separated in a single 36-min run using a Dionex CarboPac PA 10 0 column and the new quadruple-potential waveform, originally tailored for oligosaccharide separation. No measurable amounts of F3 and GF4 were detect ed within the group Of studied fruit products. Peak identification was real ized using standards. The method is easy, reproducible, and sensitive since as little as 28 mug of sugar per gram dry matter can be quantified. Banana and plum are the varieties containing the highest levels of fructans (abou t 6000 mug per gram dry matter). The maturity of the fruit appears to have a great influence on the level of GF2. Samples of apple-banana stewed fruit s contained the highest total fructan concentration (about 700 mug per gram dry matter). Accurate quantification of fructans will allow more precise n utritional formulation and diet selection for higher fructan consumption. ( C) 2001 Elsevier Science BN. All rights reserved.