Optimization and validation of the extraction, purification and analysis of galacto-oligosaccharides (GOS) in beans

Abstract

Pulses are rich in protein, dietary fiber, minerals and vitamins and their consumption promotes beneficial metabolic responses. However, postprandial gastrointestinal discomfort decreases the overall interest for pulses. Side effects are mostly attributed to Galacto-oligosaccharides (GOS), a group of indigestible carbohydrates formed by galactose monomers linked to a sucrose molecule by α (1→6) glycosidic linkage. Reducing these oligosaccharides is of interest to enhance pulse consumption; nevertheless, a reliable and reproducible extraction and analysis method needs to be developed. In this work, we optimized and validated the extraction and purification of GOS in red kidney bean (Phaseolus vulgaris), and the subsequent quantification through high-performance anion-exchange chromatography (HPAEC-PAD) and gas chromatography/mass spectrometry (GC/MS). With an optimized derivatization (to make them volatile) procedure, the GC/MS was more reproducible and reliable to identify and quantify the GOS content in 6 native bean kernels and canned whole beans exposed to different processing conditions.