Quantitative Validation of the In-Bean Approach in Coffee Roasting

The representativeness of the so-called biomimetic "in-bean" technique was studied by following the formation of target aroma compounds during the roasting course (10 points from 0 to 400 s) in recombined coffee beans and non-treated green coffee reference beans. For this purpose, the water-soluble fraction was replaced by a biomimetic recombinate in reconstituted beans prior to roasting. The targeted analysis of key aroma compounds was performed by means of the stable isotope dilution assay and solid-phase microextraction-gas chromatography-mass spectrometry of roasted and ground coffee samples. The results were compared to the quantitative data on a green coffee reference roasted under the same conditions. The results showed similar formation kinetics for most of the evaluated volatiles, such as Strecker aldehydes, alkylpyrazines, or α-diketones. In addition, the final quantities of key odorants in both types of samples were quite comparable. Hence, the refined biomimetic approach was validated as a valuable tool in studying different aspects of flavor formation upon coffee roasting.