ACAI COFFEE: DETERMINATION OF TOTAL ANTHOCYANIN, TOTAL PHENOLIC COMPOUNDS, TOTAL FLAVONOIDS, AND FLAVONOL CONTENTS IN COMMERCIAL SAMPLES.

The beverage obtained by roasting the seeds of the açaí palm (Euterpe oleracea Martius), also known as “açaí coffee,” has been associated with a reduced risk of chronic diseases due to the presence of bioactive compounds capable of mitigating oxidative stress and modulating the gut microbiota. This study aimed to determine the concentrations of total anthocyanins, total phenolic compounds, total flavonoids, and flavonols in three commercial brands of açaí coffee. The samples were coded as A (produced in Porto Velho, in the state of Rondônia), B (produced on Ipanema Island, Afuá, in the state of Pará), and C (produced in the city of Castanhal, in Pará). All assays were performed with five replicates in triplicate. Anthocyanins and flavonols were determined by UV-visible spectrophotometry in an extract prepared with 95% ethanol and 1.5 mol L⁻¹ HCl in an 85:15 (v/v) ratio, with results expressed in mg of anthocyanins/100 g and mg of quercetin/100 g, respectively. Total phenolic compounds were determined using the Folin-Ciocalteu method, with results expressed in mg of gallic acid equivalent (GAE)/100 g. Total flavonoids were determined using the FeCl₃ method, with results expressed in mg of quercetin (QE)/L. The data exhibited a nonparametric distribution, and the Kruskal-Wallis and Wilcoxon tests were applied with a significance level of 5%. The total anthocyanin concentrations (mg anthocyanins/100 g) were: 3.5 ± 0.1 for sample A; 35.9 ± 0.8 for B; and 95.8 ± 2.5 for C. For total phenolic compounds, the concentrations (mg GAE/100 g) were: 352.9 ± 18.7 for A; 2,632.9 ± 275.1 for B; and 5,146.9 ± 368.1 for C. The concentrations of total flavonoids were: 18.0 ± 0.7 mg QE/L for A; 198.4 ± 30.7 for B; and 383.2 ± 40.7 for C. For flavonols (mg QE/100 g), the values were: 39.6 ± 0.5 for sample A; 180.8 ± 6.5 for B; and 249.5 ± 8.7 for C. For anthocyanins, total phenolics, total flavonoids, and flavonols, all samples differed statistically from one another according to the Wilcoxon test (p < 0.05). These variations may be associated with the planting region, edaphoclimatic conditions, relative humidity, soil moisture, solar radiation on the açaí palm, and the fruit’s stage of ripeness at harvest. Furthermore, they may be related to storage conditions, handling of the fresh seeds, as well as the time-temperature profile during roasting and the degree of grinding, all of which directly influence the preservation or degradation of bioactive compounds. The results suggest the need to standardize and optimize the postharvest and processing stages of the açaí seeds to ensure the functional quality and stability of bioactive compounds in commercial açaí coffee, even given possible variations among growing locations.