Analysis of Caffeine, Chlorogenic Acid, Trigonelline, and Volatile Compounds in Cold Brew Coffee Using High-Performance Liquid Chromatography and Solid-Phase Microextraction-Gas Chromatography-Mass Spectrometry.

Jeongae Heo,Koushik Adhikari,Jeehyun Lee,Kap Seong Choi

doi:10.3390/foods9121746

Abstract

This study investigated the non-volatile and volatile compounds in samples of cold brew (CB) coffee, coffee from a coffee shop (CS), ready-to-drink (RTD) coffee, and brewed coffee from a coffee maker (CM). The volatile compounds were identified using headspace solid-phase microextraction with gas chromatography-mass spectrometry, and the samples were treated with high-performance liquid chromatography for the quantification of caffeine, chlorogenic acid, and trigonelline. The results indicate that RTD coffee had the lowest amounts of non-volatile compounds. A total of 36 volatile compounds were semi-quantified; the contents of most volatile compounds in CS and Folgers samples were higher than those in CB and CM samples. The contents of 25 volatile compounds in the CM sample were higher than those in the CB sample. The consumer and instrumental data show that the bitterness intensity was correlated with pyrazines, pyrroles, and guaiacols, whereas the coffeeID intensity was correlated with phenols. Semi-quantification and principal component analysis results show that the extraction method and temperature could influence the volatile compound profiles.

Highlights

Coffee is one of the most complex beverages because it contains many non-volatile and volatile compounds generated during the brewing process
Bitterness was one of the main sensory attributes influencing consumer acceptability [15]. Both caffeine and chlorogenic acid contributed to the bitterness, whereas the latter was responsible for astringency [1,16]
This study revealed the caffeine, chlorogenic acid, trigonelline, and volatile compound profiles of cold brew (CB)

Summary

Introduction

Coffee is one of the most complex beverages because it contains many non-volatile and volatile compounds generated during the brewing process. Non-volatile compounds degrade when they undergo thermal processing involving roasting. Chlorogenic acid and trigonelline are rapidly degraded during roasting, and phenolic compounds and pyridines/pyrroles are produced, respectively [3]. These newly formed compounds, along with other volatile compounds, influence the coffee quality or flavor. Considerable research has been conducted on coffee volatiles, especially the volatile compounds in hot coffee from an espresso machine [4] and coffee that undergoes different degrees of roasting at varying temperature and time [5], using headspace solid-phase microextraction (HS-SPME)

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