Temperature-driven variation of bioactive compounds in a beverage made from roasted açaí seeds using a capsule coffee maker

Açaí seeds, which make up 85% of the fruit, are often discarded despite being rich in bioactive compounds like phenolics and inulin. Roasting these seeds allows their reuse in beverages known as “açaí coffee”, however, the impact of preparation parameters, like temperature, remains unclear. This study evaluated how different brewing temperatures in a capsule coffee maker affect the extraction of bioactive compounds from roasted açaí seed powder. Roasted açaí seeds under two different conditions (175 °C for 20 minutes and 200 °C for 22 minutes) were ground and the powders were packed into reusable capsules and brewed using an Arno Genio S Plus capsule coffee maker at four different temperatures (28.5, 44.0, 59.5, and 75.0 °C), with a powder-to-water ratio of 1:10 (g/mL). Total tannins were quantified by Folin-Dennis reagent, total phenolics by the Folin-Ciocalteu method, and inulin content was determined via ion chromatography. Analyses were performed in triplicate and analysis of variance and Tukey mean test were performed at the 5% significance level using the Statistica software. For seeds roasted at 175 °C, total tannins ranged from 4.26 to 4.61 g/L, with the highest concentration observed at 75 °C brewing temperature, showing significant difference from the lowest temperature. Total phenolics were significantly higher at 44.0 °C and above (31.83–32.59 mg CAE/g) compared to 28.5 °C (29.39 mg CAE/g). Inulin content remained relatively stable (2.20–2.65 g/100 g), except for a slight decrease at 44.0 °C. For seeds roasted at 200 °C, total tannins were substantially lower (1.84–1.95 g/L) and showed no significant variation across temperatures Total phenolics increased significantly from 18.46 mg CAE/g at 28.5 °C to about 29.6 mg CAE/g at 59.5 °C and 75.0 °C. Inulin was only detected at 75.0 °C (2.32 g/100 g). Higher roasting temperature reduces tannin extraction but can still yield considerable phenolics and inulin at optimal brewing temperatures. The increase in phenolic content with brewing temperature may be due to enhanced solubility and extraction efficiency. Brewing temperature in capsule coffee makers significantly influences the extraction of bioactive compounds from roasted açaí seed powders. Seeds roasted at 175 °C yielded higher tannin content, while phenolic extraction increased with brewing temperature regardless of roasting conditions. Inulin content was generally stable but was only detected at the highest brewing temperature in the 200 °C roast. These findings show the potential to optimize beverage preparation to maximize health-related compounds in açaí seed-based drinks.