Determining 1-kestose, nystose and raffinose oligosaccharides in grape juices and wines using HPLC: method validation and characterization of products from Northeast Brazil

The objective of this work was to validate a method for direct determination in grape juice and wine of 1-kestose, nystose and raffinose oligosaccharides by reversed-phase high-performance liquid chromatography with refractive index detection using a new type of RP-C18 column (150 × 4.6 mm, 4 µm) with polar end-capping. The validated methodology was also used to characterize grape juice and fine wine products from Northeastern Brazil; and presented suitable linearity, precision, recovery, limits of detection and quantification. The method presented good specificity, revealing that sugars, organic acids, and ethanol (the main interferences in refraction detection) did not influence the quantification of the studied oligosaccharides. The main oligosaccharide found was 1-kestose (approximately 50% of the samples), followed by raffinose (20% of the samples). The results obtained in this are an indication that grape juices and wines have the potential to be functional beverages in relation to the presence of prebiotics.