2.2. Preparation of samples and fermentation
20% (w/v) instant coffee was mixed with varying amounts of sugar (1–10%, w/v) and dissolved in 100 mL of water. Instant baker's yeast (1–2%,w/v)was added. Fermentationwas carried out at 30 °C in tightly closed beakers of 250 mL placed in an orbital shaker (100 rpm). Sampling was performed at certain time intervals to monitor the changes in the concentrations of acrylamide and HMF.