Effects of sulfur water extraction on anthocyanins properties of tepals in flower of saffron (Crocus sativus L).

A sulfur solution with different metabisulfite concentrations (100, 400, 700, 1,000 and 2,000 ppm) was used to extract anthocyanins from saffron tepals. The extraction process was compared with acidified ethanol solution at similar extraction times of 20, 40, 60, 120, and 180 min at 40 °C. The recovery of anthocyanins with sulfur solution was higher than ethanol extraction and reached to 700 mg anthocyanins/100 g, when the sulfur concentration and extraction time were 700 ppm and 60 min, respectively. HPLC analysis showed that anthocyanins extracted with sulfur solution followed by partial desulfurization and reducing sulfur content (to less than 250 ppm) had around 100 % more cyanidin 3 glucosides and 100 % less pelargonidin 3,5 glucosides in comparison with ethanol extraction. Additionally, the color of low-sulfured anthocyanins had more saturation (chroma), less lightness, and more stability than the one extracted with ethanol solution. While monomeric and polymeric anthocyanins extracted with sulfur solution had less than 1 % changes after 3 h extraction time, they had more than 12 % changes when they extracted with alcoholic solution at similar conditions. Overall, the sulfur method had a potential to extract stable anthocyanins from waste and discarded saffron tepals in aqueous solvent, and with higher quantity and quality (more attractive color) than conventional ethanol extraction method.