The demand for natural pigments in the food industry is increasing. Color and stability of anthocyanins of chagalapoli ( K.) fruit added to an isotonic beverage as microcapsules and free extract were evaluated at two temperatures (4 and 25 °C) in the absence of light. Anthocyanins degradation followed first-order kinetics in the evaluated conditions. The stability of anthocyanins, measured by the variables reaction rate (K), half-life time (t), and anthocyanin retention (AR), was affected significantly ( < 0.01) by temperature. At the end of storage at 4 °C, AR was 91.2 ± 0.28% and 89.63 ± 0.22% in the beverages with microcapsules (BM) and with anthocyanins from extract (BE), respectively, without a significant difference ( ≥ 0.05) between them. However, at 25 °C, AR in the BM was 53.72 ± 0.27%, a significantly lower value ( ≤ 0.05) than that in BE (58.83 ± 1.37%). The color difference values (ΔE) in beverages stored at 4 °C were 3.81 and 2.17 for BM and BE, respectively, while at 25 °C, it was 8.57 and 8.21, respectively. The most stable anthocyanin was cyanidin 3-galactoside. Chagalapoli anthocyanins, both as microcapsules or as an extract, are adequate for adding natural color to isotonic beverages.