The juice making process causes the significant degradation of anthocyanin pigments. The highest loss of anthocyanins occurs during the depectinization and pressing steps. Studying the mechanisms of pigments degradation will be essential for optimization the manufacture conditions and implementation of technology allowing to keep the natural colour of juice. The article presents the mechanisms cause the loss of anthocyanins during the initial step of juice production, which is the depectinization of mash. The loss of anthocyanins during the depectinization is due to the activity of fruit endogenous enzymes, activity of enzyme preparation uses for this process and the presence of metal ions and oxygen.