Extraction and characterization of low molecular weight bioactive carbohydrates from mung bean (Vigna radiata)

Due to the great interest in obtaining natural bioactive carbohydrates to be used as functional ingredients, a selective microwave assisted extraction (MAE) method was optimized to ensure the exhaustive extraction of inositols and a-galactooligosaccharides (alpha-GOS) from mung bean. Thereafter, a comprehensive characterization of these compounds was carried out by gas chromatography coupled to mass spectrometry (GC-MS). Apart from free inositols and a-GOS, several glycosyl-methyl-scyllo-inositols and glycosyl-inositols were detected for the first time in this legume. Under optimized MAE conditions (0.5 g dry sample, 2 cycles of 3 min, 50 degrees C, 10 mL 50:50 ethanol: water, v:v), bioactive carbohydrates yields were similar to those found using solid-liquid extraction (SLE), but with shorter analytical times. Concentrations of bioactive carbohydrates in MAE extracts from samples of different geographical origins ranged between 74.1 and 104.2 mg.g(-1) dry sample. MAE was proved a good alternative to SLE to obtain extracts enriched in bioactive carbohydrates.