Bioaccessibility of polyphenols released and associated to dietary fibre in calyces and decoction residues of Roselle (Hibiscus sabdariffa L.)

Roselle (Hibiscus sabdariffa L.) dry calyces and decoction residues are a good source of dietary fibre (DF) and polyphenols (PP) with antioxidant capacity. The aim of this study was to evaluate the bioaccessibility of PP in complete calyces and decoction residues in Roselle. The results show that decoction residues from calyces release high quantities of PP content (296.03 ± 22.56 mg GAE/g db), whereas complete calyces had higher PP content associated with soluble DF (117.31 ± 3.31 mg GAE/g db). Released PP being higher than that obtained to convectional aqueous-organic extraction. Gallic (46.95%), syringic (42.93%) and caffeic (10.12%) acids were found in PP released from complete calyces. However, caffeic (75.28%), gallic (14.09%), and chlorogenic (10.62%) acids were identified in decoction residues. PP bioaccessibility in decoction residues and complete calyces was 71.72 and 26.68%, respectively. Released PP from decoction residues are bioaccessible in the gastrointestinal tract.