FIGURE 1.

Absorption spectra and colors of dye extracts of calyces of Hibiscus sabdariffa in different solutions. (a) Absorption spectra determined in dH₂O of the dyes extracted by different temperatures and solvents. The absorption peaks for all the samples were at 520 nm. (b) Absorption spectra determined in different buffers and pH of the dye extract (CM). The peaks for pH 3.6, 4.6, 5.6, 6.6, 7.6, and 8.6 were at 530, 538, 536, 559, 583, and 592 nm, respectively. (c) Colors of the dye extract (CM) in dH₂O and buffers at different pH. AH, acetate‐HCl buffer; BW, boiling distilled water dye extract; CM, cold methanol dye extract; CMA, cold acidified methanol dye extract; CW, cold distilled water dye extract; dH₂O, distilled water; HM, hot methanol dye extract; HMA, hot acidified methanol dye extract; HW, hot distilled water dye extract; PBS, phosphate buffer saline; TBH, tris base‐HCl buffer