β-Cyclodextrin-assisted extraction and green chromatographic analysis of Hibiscus sabdariffa L. anthocyanins and the effects of gallic/ferulic/caffeic acids on their stability in beverages

Abstract

This study aimed to develop a green approach for extraction and determination of anthocyanins from Hibiscus sabdariffa calyx using a hydroxypropyl-β-cyclodextrin (HPβ-CD)-assisted extraction technique coupled with HPLC-DAD analysis and to investigate the effects of gallic/ferulic/caffeic acids on the stability of H. sabdariffa anthocyanins in beverages. HPβ-CD-assisted extraction of total anthocyanins from H. sabdariffa calyx was optimized using a Box–Behnken design-response surface methodology, and extraction at 54 °C for 53 min using HPβ-CD aqueous solution (3.7 g/100 mL) gave the maximum extraction yield of total anthocyanins (4.82 ± 0.13 mg/g). A work-safe and rapid HPLC-DAD method was developed for analysing H. sabdariffa anthocyanins using ethanol and a tartaric acid aqueous solution as mobile phases, and the main anthocyanin peaks were determined as delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside using a two-dimensional HPLC-DAD/ESI-MS method. Method validation showed that the developed method was accurate, stable and reliable for the analysis of H. sabdariffa anthocyanins. Additionally, the degradation of delphinidin-3-O-sambubioside, cyanidin-3-O-sambubioside and total anthocyanins from H. sabdariffa calyx ideally followed a first-order model (R2 > 0.98) in beverages alone or with additional phenolic acids. Gallic acid improved the stability of H. sabdariffa anthocyanins better than ferulic and caffeic acids, and adding/increasing ferulic and caffeic acids accelerated anthocyanin degradation.