Malteação de grãos de arroz e aplicação na obtenção de cervejas

Abstract

Barley is the cereal traditionally used in the production of malt for beer; however, rice has emerged as a promising alternative for obtaining gluten-free products with differentiated sensory profiles. The objective of this study was to produce malts from rice grains, including a base malt and two specialty malts, and apply them in beer production, comparing them to a standard barley-based formulation. Rice grains were subjected to steeping at 25 °C for 44 hours and germination at 21 °C for 5 days. Drying was carried out in an oven using a time vs. temperature binomial of 45, 50, 55 and 60 °C for 12 hours each. After manual sieving, the base malt was obtained. From this malt, two specialty malts were produced: caramel malt 1, roasted in an oven at 120 °C for 180 min, and caramel malt 2, roasted at 180 °C for 120 min. Malt samples were sent to Agraria Malte (Paraná, Brazil) for physicochemical characterization. Four beer formulations were produced: one with barley malt and three with rice malts. Mashing was conducted with a time vs. temperature binomial of 64 °C/60 min, 73 °C/20 min and 78 °C/10 min. Fermentation occurred at 12 °C, followed by maturation at 5 °C. The beers were bottled in glass bottles and decarbonated prior to analysis. The following physicochemical parameters were evaluated: original and final gravity, color, bitterness, pH, titratable acidity, alcohol content, real extract and original extract. The volatile profile was determined by gas chromatography-mass spectrometry (GC-MS), and sensory analysis was performed with untrained panelists, with word cloud generation. The rice malt formulations presented alcohol contents around 2.2% v/v and high real extract values (7.9% m/v). The formulation containing 25% caramel malt 1 stood out for the detection of isoamyl acetate, ethyl hexanoate and ethyl octanoate. The control formulation presented complete fermentation (5.78% v/v) and a neutral sensory profile. Sensory analysis evidenced perceptible differences among the formulations. The production of specialty rice malts proved to be promising for obtaining differentiated sensory profiles.