Anthocyanins extraction from Hibiscus sabdariffa and identification of phenolic compounds associated with their stability.

Background: One of the main disadvantages of red pigments used in foods is their low extraction yield and storage stability. Roselle flowers are sources of anthocyanins; however, these are unstable during storage, but this could be improved with phenolic compounds, which establish bonds with the anthocyanins. The aim of this work was to identify conditions to improve the extraction efficiency and color stability of Hibiscus sabdariffa extract and, furthermore, to identify the phenolic compounds associated with color stability of roselle.

Results: The temperature of extraction (35 and 75 °C), the time of extraction (15 and 60 min), type of acid (acetic and citric), percentage of acid (0.5 and 2.0%) and the water:ethanol ratio (20:80 and 80:20) did not affect the yield of anthocyanins; only the solid:solvent ratio had an effect in the anthocyanin extraction yield. The extraction with 80% ethanol decreased up to 50% the anthocyanin degradation in the extracts stored at 4, 25, 35, 45, and 80 °C. Phenolic acids and flavonoids were quantified by ultrahigh-performance liquid chromatography coupled with triple quadrupole electrospray ionization mass spectrometry. These compounds were analyzed using principal component analysis, and the H. sabdariffa extract, with greater stability, was found to be associated with the presence of quercetin, myricetin, kaempferol 3-O-glucose, ellagic acid, and rutin.

Conclusion: H. sabdariffa extract with increased color stability was extracted with a higher proportion of ethanol and the improvement in the color stability was attributed to the co-extraction of phenolic compounds, principally flavonoids that could interact with anthocyanins and stabilize them. © 2020 Society of Chemical Industry.