The objectives were to quantify the total polyphenols and the antioxidant capacity by inhibiting the DPPH and ABTSº+ radicals in skins/peel and seed of tuna, cocoa, grape and uvilla. The samples were dried at 60 °C/12 h and ground; an extract water/methanol (v/v) was prepared; it was macerated for 24 hours and then centrifuged at 10000 rpm/10 min/4 ºC. The results were analyzed using the completely randomized design (CRD; DCA – acronym in Spanish) and a multivariate analysis. The content of the polyphenols varied between 9.07 and 1.78 gEAG/100g. The antioxidant capacity against the DPPH free radical had the following order: grape seed, cape gooseberry skin and seed > grape skin and cacao skin > cacao hull > purple prickly pear peel > yellow prickly pear seed > yellow prickly pear skin > yellow prickly pear peel > purple prickly pear skin > purple prickly pear seed. The correlation between total polyphenols and the antioxidant activity (DPPH) efficiency was r2 = 0.934. The greatest antioxidant capacity against the ABTSº+ free radical was found in the cape gooseberry skin and seed and the grape seed; the least was found in the yellow prickly pear peel. According to the principal component analysis, the best treatments were the cape gooseberry skin and seed and the grape seed.