Advanced instrumental characterization of the coffee extracts produced by pilot scale instant coffee process

Abstract

Coffee, with production exceeding 10.3 million tonnes in 2018, is one of the most widespread commodities consumed world-wide. One of the increasingly popular coffee products is instant coffee, with consumption exceeding 1.6 million tonnes in 2017. In this work, we present how the combination of 1H NMR and GC–MS allows the characterization of samples from the small pilot-scale instant coffee process. Results were compared with measurements for filter coffee made from the same coffee beans to better evaluate the effects of processing. In the coffee extracted at lower temperatures, a higher concentration of aroma compounds can be detected. This is particularly the case for compounds responsible for earthy (pyrazines) and woody (guaiacols) aroma notes. Also, for the coffee extracted at the highest temperature, a higher level of cyclotene giving undesired burnt and bready aroma is seen. The caffeine content in instant coffees was lower than in the filter coffee (49\u2009±\u200913 up to 62\u2009±\u20095 mg/100 mL brew for instant compared with 84\u2009±\u200915 mg/100 mL brew for filter coffee). The same was observed for acetic acid, while the concentrations of citric and quinic acids are lower in the filter coffee than in the reconstituted instant coffee.