Optimization and comparison of maceration and ultrassound assisted extraction systems for the production of a colorant extract from Hibiscus sabdariffa L. flowers
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European Union Regional Development Fund: Programme Portugal-NORTE2020
(Project NORTE-01-0145-FEDER-023289: DeCodE; Project NORTE-01-0247-FEDER-
024479: ValorNatural®); Programmme INTERREG V-A Espanha-Portugal (POCTEP) 2014-
2020 (Project 0377_Iberphenol_6_E). And Xunta de Galicia, Spain, for M.A. Prieto grant.
Hibiscus sabdariffa L. is an herbaceous medicinal plantused as infusion for the treatment of several disorders, namely, fever and high blood pressure, gastrointestinal and hepatic diseases. In addition to those health benefits, the calyces area potential source of natural pigments, due to its high content in anthocyanins. This work aimed to optimize the experimental conditions of anthocyanins’extraction from dried calyces of H. sabdariffa, comparing two methodologies, maceration and ultrasound assisted extraction, in order to develop a natural colorant. To obtain the conditions that maximize anthocyanins’ extraction, a response surface methodology (RSM) was applied using the circumscribed central composite design of three variables with five levels. Time, temperature and ethanol - water proportion - in the case of maceration, were the relevant independent variables, while for ultrasound assisted extraction, the ultrasonic power was used instead of temperature which was kept constant. Two anthocyanin compounds were identified by HPLC-DAD-ESI/MS: delphinidin3-sambubioside and cyanidin-3-sambubioside. The responses used as criteria were the quantification of the identified anthocyanins and the extraction yield of the final residue. Ultrasound assisted extraction proved to be the most effective method: 43 min, 390 W and 46 % of ethanol. At these optimal conditions, the extraction yield was 61.2%, with a total anthocyanins’ content of 23.1 mg/g dried plant, and 47.5 mg/g extract. Additionally, the response values were slightly improved by studying the solid/liquid ratio effect using the optimal conditions in dose-response format (5 to 200 g/L), showing continuously decreasing values as the solid/liquid ratio increases. Overall, the obtained results showed the possibility of using H. sabdariffa flowers as a source of anthocyanin compounds for industrial applications.
