Antioxidant properties and color of Hibiscus sabdariffa extracts

liquid extracts of dried roselle (hibiscus sabdariffa) calyces obtained using ethanol:water (50:50 and 70:30%, v/v), water, ethanol:1.5 n hcl (85:25%, v/v), and ethanol (96%) to evaluate selected antioxidant characteristics (phenolic compounds and antioxidant capacity), color parameters (l, a, and b), and anthocyanins (delphinidin-3-o-sambubioside, delphinidin-3-o-glucoside (myrtillin), and cyanidin-3-o-sambubioside) by high performance liquid chromatography (hplc). the total monomeric anthocyanin content was also assessed using the differential ph technique. the phenolic compound content ranged from 1,067±22 (in ethanol) to 2,649±96 (in ethanol:water 70:30%) mg of gallic acid100 g-1 of dehydrated calyces, and the antioxidant capacity ranged from 3.11±0.50 (in ethanol) to 8.0±0.2 mmoles of trolox100 g-1 of calyces. the total monomeric anthocyanin content (209±21 mg100 g-1) was similar to that obtained using the hplc technique (215±31 mg100 g-1) when extracting the calyces with the 50:50% (v/v) ethanol:water solution. the deepest red-purple (hue = 62.50±0.34) colored solution was observed when extracting the calyces with ethanol. the antioxidant and color properties of roselle calyces make the extracts ideal for use in foods as a natural extract, concentrate, or powder.