Prebiotic oligosaccharides from artichoke industrial waste: evaluation of different extraction methods

Artichoke industrial wastes, which are about 70% of the total artichoke flower, contain prebiotic sugar, such as fructooligosaccharides. In this study, the effect of ultrasound by two different modes (direct and indirect sonication) to enhance the conventional extraction has been evaluated, in terms of yield of prebiotic sugar from artichoke industrial waste. The ultrasound with direct sonication showed to be more efficient to produce rich-prebiotic sugars extracts than conventional and indirect sonication processes. Therefore, variables such as extraction temperature (50-70 °C), time (5-120 min) and power (240-480 W) have been investigated for the ultrasound extraction with direct sonication, in order to improve the prebiotic sugars yield. The chosen extraction conditions were: 10 min, 60 °C and 360 W. Ultra performance liquid chromatography-mass spectrometry (UPLC-MS) method was used to identify and quantify the sugar extracted. The artichoke waste extract is a potential source of prebiotic sugars, containing 1-kestose, nystose, fructofuranosylnystose and raffinose.