Evaluation of Volatile and Non-Volatile Compounds in Specialty and Traditional Coffees from the Circuito das Águas Paulista Region

Abstract

Coffee, renowned for its aroma and flavor, ranks second in global consumption. Key compounds in coffee beans significantly influence their sensory properties in green and roasted forms. Brazil, a leading coffee producer and exporter, benefits from the adaptability of coffee plants due to its diverse geographical features. The Circuito das Águas Paulista region, in particular, provides an ideal environment for high-quality coffee cultivation, producing coffees that surpass the 80-point threshold needed to attain specialty coffee status. This study evaluated 17 roasted Coffea arabica samples: 12 from the 2020/2021 harvest (six specialty and six traditional) and 5 from the 2022/2023 harvest. Chemical composition was assessed using UV-Vis spectrophotometry, HPLC, GC-FID, and chemometric tools. Total phenolic content, measured by the Folin-Ciocalteu method, ranged from 3371 to 3968 mg GAE/100 g. Caffeine and chlorogenic acid contents (507–1006 mg/100 g and 453–1004 mg/100 g, respectively) were determined by HPLC. Volatile compounds such as diacetyl (37.01–108.28 µg/100 g) and 2-methylpyrazine (2.41–3.38 µg/100 g) were quantified by GC-FID with headspace sampling. Significant differences were found between specialty and traditional coffees, particularly in diacetyl, which was more abundant in specialty samples and may act as a marker. Principal Component Analysis effectively distinguished the two groups, with 2-methylpyrazine playing a key role in traditional coffees. Comparison between harvests revealed notable variations in caffeine, gallic acid, chlorogenic acid, 3,4-dihydroxybenzoic acid, and 2-methylpyrazine, suggesting that environmental conditions, such as frost, can affect coffee chemistry and quality. The analytical advance of this work resides in the integration of complementary analytical techniques with chemometric analysis, providing a robust approach to discriminate coffee categories and evaluate environmental influences on their chemical composition.