Amazonian Robusta green coffee volatiles and their correlation with cup quality in samples from Rondônia indigenous, Acre and Amazonas

Coffee cultivation using the species Coffea canephora has gained increasing prominence and visibility in the northern region of Brazil, especially in Rondônia through Indigenous farming, as well as in Acre and Amazonas by other coffee growers. However, the chemistry behind aroma and flavor remains unclear, as each producer exhibits unique characteristics despite cultivating the same coffee species. The objective of this study was to evaluate the volatile metabolome of green coffee beans and to correlate the identified compounds with the predetermined global quality scores of roasted coffees. Volatile compounds were extracted and analyzed using HS-SPME-GC-MS, and the data were assessed through multivariate analyses. The coffee cultivated by Indigenous producers in Rondônia and by farmers in Acre each presented 41 volatile compounds, while the coffee from Amazonas showed 45 compounds. Nonetheless, the compounds with the highest average peak areas common across all three of the three origins included benzoic acid, 2-hydroxy-, ethyl ester, acetic acid, caffeine, methyl salicylate, hexadecanoic acid, ethyl ester, ethyl acetate, triethyl phosphate, benzeneacetic acid, ethyl ester, phenylethyl alcohol, and 2-heptanol. Some compounds were found exclusively in one or two of the regional samples. For example, butanal, 3-methyl-, propanoic acid, 2-hydroxy-, ethyl ester, and decane, 2,3,5-trimethyl-, were only present in the Amazonas sample. Compounds such as tridecane, hexadecane, 2-pentanol, 2-butanone, 3-hydroxy-, decane, 3,8-dimethyl-, and octane, 2,4,6-trimethyl- were detected only in the Indigenous coffee from Rondônia. Meanwhile, triacetin and decane, 3,6-dimethyl- were found exclusively in the Acre sample. Each compound was individually correlated with the overall quality predetermined for the roasted coffee: Amazonas (81 points), Acre (77 points), and Rondônia indigenous (89 points). With strong correlations above 0.9, the overall quality of coffee from Amazonas is positively associated with 3-methylbutanoic acid, 3-methyl-2-butenoic acid ethyl ester, acetic acid 2-phenylethyl ester, 2-hydroxybenzoic acid ethyl ester, benzenepropanoic acid ethyl ester, nonadecane, phthalic acid decyl isobutyl ester, and 14-methylpentadecanoic acid methyl ester. The overall quality of coffee from Acre is positively associated with 3-methylbutanoic acid, pentanoic acid ethyl ester, benzaldehyde, benzeneacetic acid ethyl ester, dodecane, and hexadecanoic acid methyl ester. The overall quality of indigenous coffee from Rondônia is positively associated with ethyl acetate, 2-pentanol, 2-heptanol, benzaldehyde, benzoic acid ethyl ester, butanedioic acid diethyl ester, octanoic acid ethyl ester, and methyl salicylate. These results highlight the aromatic diversity of Amazonian coffees, helping to identify the most volatile-relevant compounds, contributing to the field of Coffea canephora metabolomics.