Interactions between volatile and nonvolatile coffee components. 1. Screening of nonvolatile components

Area of Science:

• Food Chemistry
• Sensory Science
• Analytical Chemistry

Background:

• Coffee aroma is a complex interplay of volatile and nonvolatile compounds.
• Understanding these interactions is key to coffee quality and flavor development.
• Previous studies have hinted at nonvolatile contributions to aroma perception.

Purpose of the Study:

• To identify specific nonvolatile coffee constituents responsible for interactions with key aroma compounds.
• To quantify the impact of coffee roasting levels on these interactions.
• To elucidate the chemical basis of aroma-nonvolatile interactions in coffee.

Main Methods:

• Headspace solid-phase microextraction (SPME) was used to measure interactions.
• Coffee brews from light, medium, and dark roasted beans were analyzed.
• Fractionation techniques including chromatography and dialysis were employed.

Main Results:

• Dark roasted coffee brews showed slightly higher reactivity with aroma compounds than light roasted brews.
• Pure coffee constituents like caffeine and chlorogenic acid exhibited minimal interactions.
• Low molecular weight, positively charged melanoidins demonstrated significant interactions with volatiles.

Conclusions:

• Melanoidins, especially those with low molecular weight and positive charge, are primary drivers of nonvolatile-aroma interactions.
• A strong correlation exists between melanoidin/protein content and the extent of these interactions (R = 0.83-0.98).
• Chlorogenic acids and carbohydrates play a minor role in these complex matrix interactions.