ANTIOXIDANT CAPACITY AND Fe2+ ION CHELATING CAPACITY IN COMMERCIALLY AVAILABLE AÇAÍ COFFEES

The determination of antioxidant and chelating capacity is important in the evaluation of a food’s functional potential for the prevention of cellular oxidation, degenerative diseases, aging, and cancer. Açaí coffee is produced by roasting açaí seeds and has been widely used for disease prevention. The objective of this study was to determine the antioxidant capacity and Fe²⁺ chelating capacity of commercial açaí coffees. To this end, three commercial samples from different brands, coded as A, B, and C, were collected. The antioxidant capacity was determined using the DPPH, ABTS, and Frap methods, in all assays, Trolox was used as the standard, with results expressed in µmol TEAC/g. The sample extracts for determining antioxidant capacity were prepared in metanol 50% (v:v). Fe²⁺ ion chelating activity was determined using the ferrozine method, with results expressed as AQ (%), the extract was prepared in water at 70 °C using an ultrasonic bath at 50 °C for 20 minutes. All extracts were centrifuged at 6026 xg for 15 minutes at 4 °C, and the supernatant was collected for the reactions. The extracts were prepared in 5 replicates, with triplicate readings for each assay. Statistical analysis consisted of the Shapiro-Wilk normality test, for normally distributed data, ANOVA and the Tukey test were used, and for non-normally distributed data, the Kruskal-Wallis and Wilcoxon tests were used. The results obtained in the ABTS assay were: 20.057 ± 2.896 for sample A; 180.664 ± 8.333 for sample B; and 633.259 ± 38.624 µmol TEAC/g for sample C. For the DPPH assay, the results were 16.550 ± 1.135 for sample A, 145.168 ± 5.483 for B, and 495.975 ± 74.574 µmol TEAC/g for C. For the Frap assay, the results were 28.024 ± 2.755 for sample A; 225.877 ± 11.146 for B; and 524.843 ± 51.521 µmol TEAC/g for C. The AQ% results were 82.23% ± 1.82 for sample A, 80.15 ± 1.893% for B, and 66.14% ± 2.71 for C. All results obtained were nonparametric, and the Kruskal-Wallis and Wilcoxon tests were applied. For the antioxidant capacity assays, all samples were statistically different from one another (p < 0.05), and a significant difference in results within the same product could be observed. As for AQ (%), only samples A and B were statistically equal to one another (p > 0.05). These differences can be attributed to the degree of fruit ripeness, as well as to storage, processing, and the roasting temperature of the coffee beans. Therefore, the results suggest that açaí coffees possess antioxidant and chelating capacity, however, it is essential to improve the harvesting and processing stages of the coffee beans to ensure product standardization and quality.