Interactions between Volatile and Nonvolatile Coffee Components. 1. Screening of Nonvolatile Components

Abstract

This study is the first of two publications that investigate the phenomena of coffee nonvolatiles interacting with coffee volatile compounds. The purpose was to identify which coffee nonvolatile(s) are responsible for the interactions observed between nonvolatile coffee brew constituents and thiols, sulfides, pyrroles, and diketones. The overall interaction of these compounds with coffee brews prepared with green coffee beans roasted at three different roasting levels (light, medium, and dark), purified nonvolatiles, and medium roasted coffee brew fractions (1% solids after 1 or 24 h) was measured using a headspace solid-phase microextraction technique. The dark roasted coffee brew was slightly more reactive toward the selected compounds than the light roasted coffee brew. Selected pure coffee constituents, such as caffeine, trigonelline, arabinogalactans, chlorogenic acid, and caffeic acid, showed few interactions with the coffee volatiles. Upon fractionation of medium roasted coffee brew by solid-phase extraction, dialysis, size exclusion chromatography, or anion exchange chromatography, characterization of each fraction, evaluation of the interactions with the aromas, and correlation between the chemical composition of the fractions and the magnitude of the interactions, the following general conclusions were drawn. (1) Low molecular weight and positively charged melanoidins present significant interactions. (2) Strong correlations were shown between the melanoidin and protein/peptide content, on one hand, and the extent of interactions, on the other hand (R = 0.83-0.98, depending on the volatile compound). (3) Chlorogenic acids and carbohydrates play a secondary role, because only weak correlations with the interactions were found in complex matrixes.

Effect of sugars on liquid–vapour partition of volatile compounds in ready‐to‐drink coffee beverages

“…[11] Other coffee compounds could be also involved in the higher retention of HE and EP in respect to water due to specific reactions or interactions. [17,18] Upon the 10% sugar addition, an effect different in respect to that determined in the case of water alone as shown by the data of the retention reported in Tables 5 and 7 was shown. [16] Some effects are also expected to occur due to the presence of high molecular carbohydrates (galactomannans and Type II arabinogalactans) as well as protein fragments.…”

“…[7] In general, at a given concentration, the release of a volatile compound from a food matrix in the headspace above depends on the mechanisms that influence the volatilization and the factors that affect them. [16][17][18] The retention capacity of coffee melanoidins was found to vary in function of the process used to dry the coffee beverage as denaturation process occurred on the melanoidins may impair the ability to interact with volatile compounds. [11][12][13] The equilibrium distribution of flavour compounds between the different phases (solid-water-oil) and the interactions, of different nature and strength, between the aroma compounds and non-volatile molecules (lipids, proteins, carbohydrates, salts) play, on the other hand, an important role in the thermodynamic aspects of the flavour release under equilibrium conditions and may suppress or enhance the presence of the aroma compounds in the gas phase.…”

“…[11][12][13] The equilibrium distribution of flavour compounds between the different phases (solid-water-oil) and the interactions, of different nature and strength, between the aroma compounds and non-volatile molecules (lipids, proteins, carbohydrates, salts) play, on the other hand, an important role in the thermodynamic aspects of the flavour release under equilibrium conditions and may suppress or enhance the presence of the aroma compounds in the gas phase. [17] In many countries is common practice to add on coffee beverages other ingredients to develop a desirable colour change, to impart a body, to reduce bitter and sour tastes, as well as to reduce the astringency of the coffee. [15] The latter ones have been recognized to be the most important compounds able to suppress the release/partition of some key aroma compounds.…”

Comparison of nine common coffee extraction methods: instrumental and sensory analysis

“…The contents of caffeine and chlorogenic acids are said to be important factors for the salubriousness of coffee. The latter are degrading during the roasting process [2,[13][14][15][16][17]. However, they are known to be important antioxidants and are active even at concentrations as low as 10 lg/ml of 5-CQA [15,18].…”

Analysis of Freshly Brewed Espresso Using a Retronasal Aroma Simulator and Influence of Milk Addition

“…Solid-phase microextraction (SPME) is a rapid, simple, inexpensive, and reproducible method used to collect released volatiles (Arthur and Pawliszyn, 1990;Yang and Peppard, 1994;Bicchi et al, 1997;Steenson et al, 2002;Jung and Ebeler, 2003;Charles-Bernard et al, 2005;López-Galilea et al, 2006). The short-duration SPME sampling method whose effectiveness for collecting fresh coffee volatiles has been reported in our previous studies (Akiyama et al, 2007(Akiyama et al, , 2008 has been applied to sample headspace volatiles and volatiles in the effluent from a retronasal aroma simulator (RAS) released from freshly brewed espresso and café latte.…”