Evaluation of 3-Methylbutanoic Acid Methyl Ester as a Factor Influencing Flavor Cleanness in Arabica Specialty Coffee

Abstract

This paper reports on the chemical compounds in arabica coffee beans with a high Specialty Coffee Association (SCA) cupping score, especially those in specialty coffee beans. We investigated the relationship between the chemical compounds and cupping scores by considering 16 types of Coffea arabica (arabica coffee) beans from Guatemala (SCA cupping score of 76.5–89.0 points). Non-targeted gas chromatography-mass spectrometry-based chemometric profiling indicated that specialty beans with a high cupping score contained considerable amounts of methyl-esterified compounds (MECs), including 3-methylbutanoic acid methyl ester (3-MBM), and other fatty acid methyl esters. The effect of MECs on flavor quality was verified by spiking the coffee brew with 3-MBM, which was the top-ranked component, as obtained through a regression model associated with cupping scores. Notably, 3-MBM was responsible for the fresh-fruity aroma and cleanness of the coffee brew. Although cleanness is a significant factor for specialty beans, the identification of compounds that contribute to cleanness has not been reported in previous research. The chemometric profiling approach coupled with spiking test validation will improve the identification and characterization of 3-MBM commonly found in arabica specialty beans. Therefore, 3-MBM, either alone or together with MECs, can be used as a marker in coffee production.

Combined sensory, volatilome and transcriptome analyses identify a limonene terpene synthase as a major contributor to the characteristic aroma of a Coffea arabica L. specialty coffee

“…Glycosylated precursors of 3-methylbutanoic acid were found to be associated with high cupping scores in green beans [ 64 ]. Sixteen different batches of roasted Guatemalan coffee beans differed in 3-methylbutanoic acid methyl ester content, a substance that was associated with the fresh, fruity aroma and cleanliness of the coffee [ 65 ]. The results of our study are in line with these finding as the volatile compound 3-methylbutanoic acid was found to be at a higher content in both green and roasted beans of the Geisha Especial genotype.…”

Effects of postharvest processing on aroma formation in roasted coffee – a review

“…Roasting can cause 3‐methylbutanoyl disaccharides (3MDs) pyrolysis in coffee. The products mainly consist of a 3‐methylbutanoic acid, which may enhance the richness of coffee flavour (Iwasa et al ., 2015; Iwasa et al ., 2021). Protein also undergoes pyrolysis and releases aromatic compounds such as alanine and asparagine (Dong et al ., 2015).…”

“…For example, acetic acid (a simple monocarboxylic acid) could bring a taste of vinegar on its own but can contribute to a wine‐like and sweet flavour paired with other compounds while a saturated short‐chain fatty acid, isovaleric acid (3‐methylbutanoic acid), with cheese‐like rancidity was also identified as a potential odorant in brewed coffee (Chin et al., 2011). Besides, quantitative analysis confirmed isovaleric acid as an indicator of excellent coffee quality, over 80 scored by Speciality Coffee Association (SCA) (Iwasa et al ., 2021). Fatty acid (FAs) fractions of triacylglycerols have a subtle but desirable flavour note in coffee.…”