ABSTRACT Waste from fruit processing can be used for obtaining additives as colorants and antioxidant compounds by extraction processes. Despite there are many works optimizing parameters as temperature and solvent concentration during this process, the mixture of solvents has not been optimized yet. Therefore, the present work aimed to find the optimum solvent mixture among water, ethanol, and acetone to obtain the maximum yields of phenolic compounds and monomeric anthocyanins from blue berry and grape marc by ultrasound-assisted extraction. For that, the Reticular Simplex Mixtures Design was used to obtain the models that can predict the optimum values of extraction yields. As a result, the quadratic model successfully fit the experimental data, demonstrating the best mixture solvents were the ones that presented a high percentage of water. This result was obtained not only for phenol...