This study is focusing on evaluation of colour fluctuation buffering of purple sweet potato anthocyanins to pH variation. The effect of copigmentation that is frequently applied in improving chemical stability of anthocyanins was tested. Especially a new strategy was attempted employing surfactants to mimic encapsulation which is proved to be effective in promoting their chemical stability. The prominent colour fluctuation buffering effect of certain surfactants was found and carefully studied by colorimetric and spectroscopic methods. To the best of our knowledge, it is the first time to report colour fluctuation buffering of anthocyanins by surfactants.