Production of 6-O-caffeoylsophorose from acylated anthocyanins derived from purple sweet potato through hydrolysis under weak acidic conditions

6-O-caffeoylsophorose (CS) is a functional component identified in vinegar produced through acetic fermentation of storage roots of purple sweetpotato cultivar Ayamurasaki. The optimum conditions of CS production was investigated using the purple sweetpotato pigment (PSP) separated from Ayamurasaki containing acylated anthocyanins in order to develop the efficient production method of CS. By heating PSP under weak acidic conditions, CS as the side chain fragment of acylaled anthocyanins was produced abundantly. The amount of produced CS was dependent on pH, and highest at pH 3.0, not on the kind difference of acids. The temperature was also an important factor to the concentration of CS : at higher temperatures the highest score was obtained in shorter time. The ratio of the highest score to anthocyanin content in original PSP was almost same at each temperature and production efficiency of CS was also similar in quantity.