PHENOLIC ENRICHMENT OF AMERICAN PALE ALE CRAFT BEER WITH COFFEA ARABICA HUSK EXTRACT VIA COLD INFUSION

Resumo

The present study aimed to develop a craft beer in the American Pale Ale (APA) style using Arabica coffee husks (Coffea arabica L. var. typica) as a functional ingredient through the cold infusion technique. This approach aims to promote sustainability and innovation in the beverage sector by valorizing coffee agro-industrial by-products as sources of bioactive compounds. The APA beer was produced following the procedures described by Palmer, with specific adaptations for laboratory and pilot-scale conditions. The methodology was based on the use of malt, hops, and yeast appropriate for this style, in compliance with technical processing guidelines. Three formulations were prepared: a control sample (C_T), with no extract addition, and two experimental samples (C₁ and C₂), supplemented with 10 mL and 20 mL of coffee husk extract per bottle, respectively. The extract was obtained by infusing the dried husks in mineral water under agitation at 200 rpm for 24 hours, followed by filtration and exposure to UV light for 10 minutes. Mashing was carried out in an automated brewing kettle with temperature rests ranging from 62 °C to 80 °C. Boiling with hop addition was performed for 10 minutes, and the wort was cooled using a plate heat exchanger. Fermentation was conducted at 19 °C for seven days, followed by maturation at 4 °C for seven days. Bottling was performed with the addition of a sucrose solution for natural carbonation (priming). Physicochemical analyses included pH, titratable acidity (%), soluble solids (°Brix), total phenolic compounds (mg GAE/L), and real extract, all performed in triplicate according to methods of the Instituto Adolfo Lutz. The results showed stability in pH (4.34 to 4.37), acidity (0.30–0.32%), and soluble solids (4.34–4.40 °Brix). The bitterness index (IBU) remained at 29 for all samples. The concentration of phenolic compounds, expressed as milligrams of gallic acid equivalents, was higher in the samples containing extract (C₁: 20.11 mg GAE/L; C₂: 18.16 mg GAE/L) compared with the control sample (10.70 mg GAE/L). Real extract was higher in formulation C₁ (0.45), indicating better incorporation of solid compounds at this intermediate concentration. These findings indicate that coffee husk extract is a promising functional additive capable of enriching craft beers with antioxidant compounds without compromising their essential physicochemical characteristics.