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

Koichi Nakahara,Harumichi Seta,Yoshihide Matsuo,Keiko Iwasa

doi:10.3390/app11125413

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.

Highlights

Coffee is a popular beverage consumed globally, yet there are no universal chemicalbased standards to assess the coffee flavor and quality, more than 800 volatile compounds have been identified in coffee beans [1,2]
Using a variety of analytical techniques, including solid-phase microextraction coupled with gas chromatography-mass spectroscopy (GC–MS) and liquid-liquid extraction coupled with GC–MS, the volatile compounds in coffee have been analyzed to characterize the variability among coffee beans [3,4,5,6,7]
Studies on the volatile compounds in coffee beans with high Specialty Coffee Association (SCA) cupping scores [13], which are regarded as the global coffee evaluation standard, specialty coffee beans with cup quality defined based on the SCA evaluation criteria, are still limited

Summary

Introduction

Coffee is a popular beverage consumed globally, yet there are no universal chemicalbased standards to assess the coffee flavor and quality, more than 800 volatile compounds have been identified in coffee beans [1,2]. Studies on the volatile compounds in coffee beans with high Specialty Coffee Association (SCA) cupping scores [13], which are regarded as the global coffee evaluation standard, specialty coffee beans with cup quality defined based on the SCA evaluation criteria, are still limited. Metabolic profiling has been used in the fields of medicine, agriculture, plant physiology, and microbiology as a comprehensive, non-targeted approach. Metabolic profiling in food science enables us to evaluate the balance of components in samples, determine the differences in samples containing multi-component compounds, and predict the correlations between bioactivity/functional activity and multi-component compounds [14,15,16]

Methods

Results

Conclusion