Composition and colour stability of anthocyanins extracted from fermented purple sweet potato culture

The components and colour stability of anthocyanins in purple sweet potato were investigated. Anthocyanins were extracted from fermented purple sweet potato culture fermented by Suzhou wine starter (Rhizopus 3.851, 3.866 and Saccharomyces cerevisiae). In these purple sweet potato anthocyanins (PSPAs), five major anthocyanins were detected by high performance liquid chromatography (HPLC). Cyanidin and peonidin were found to be the major anthocyanidins in PSPAs by acid hydrolysis of anthocyanins. PSPAs were more stable under the acid conditions (pH 2.0–4.0) than the subacid conditions (pH 5.0–6.0) as per UV–Vis absorption spectra and CIELAB colour coordinates.