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Aroma binding and stability in brewed coffee: A case study of 2-furfurylthiol

Sun, Zhenchun, Yang, Ni, Liu, Chujiao, Linforth, Robert S.T., Zhang, Xiaoming, Fisk, Ian D.
Food chemistry 2019 v.295 pp. 449-455
case studies, coffee (beverage), cysteine, methanethiol, models, odors, pH, quinones, temperature
The aroma stability of fresh coffee brew was investigated during storage over 60 min, there was a substantial reduction in available 2-furfurylthiol (2-FFT) (84%), methanethiol (72%), 3-methyl-1H-pyrole (68%) and an increase of 2-pentylfuran (65%). It is proposed that 2-FFT was reduced through reversible chemical binding and irreversible losses. Bound 2-FFT was released after cysteine addition, thereby demonstrating that a reversible binding reaction was the dominant mechanism of 2-FFT loss in natural coffee brew. The reduction in available 2-FFT was investigated at different pH and temperatures. At high pH, the reversible binding of 2-FFT was shown to protect 2-FFT from irreversible losses, while irreversible losses led to the reduction of total 2-FFT at low pH. A model reaction system was developed and a potential conjugate, hydroxyhydroquinone, was reacted with 2-FFT. Hydroxyhydroquinone also showed 2-FFT was released after cysteine addition at high pH.