Baggenstoss Juerg, Poisson Luigi, Luethi Regina, Perren Rainer, Escher Felix
Institute of Food Science and Nutrition, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland.
J Agric Food Chem. 2007 Aug 8;55(16):6685-91. doi: 10.1021/jf070338d. Epub 2007 Jul 6.
Coffee roasting experiments with air cooling versus water quench cooling were carried out on laboratory scale with a fluidized-bed hot air roasting system (200 g batch size) and on production scale with a rotating bowl roaster (320 kg batch size). Two series of coffees with different water contents resulted, which were stored at 25 degrees C under normal atmospheric conditions. Carbon dioxide desorption was followed and stability of selected aroma compounds was tested with headspace solid-phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS) and stable isotope labeled compounds as internal standards. Degassing is faster in water-quenched coffees with higher moisture content, but pore size distribution in the different coffee samples did not correlate with degassing behavior. Bean firmness, which increases with increasing moisture content, might have an influence on degassing. Air- and water-quenched coffees exhibit similar stability of most aroma compounds despite different degassing behavior. However, evolution of dimethyl trisulfide was different in coffees with increased water content. This suggests higher thiol oxidation rates, a factor that is cited to be related to a faster loss of freshness attributes.
使用流化床热风烘焙系统在实验室规模（每批200克）以及使用旋转滚筒烘焙机在生产规模（每批320千克）上进行了咖啡烘焙实验，对比了空气冷却和水淬冷却两种方式。由此得到了两组不同含水量的咖啡，并在正常大气条件下于25摄氏度储存。跟踪了二氧化碳解吸情况，并用顶空固相微萃取-气相色谱-质谱联用仪（SPME-GC-MS）以及以稳定同位素标记化合物作为内标物来测试选定香气化合物的稳定性。含水量较高的水淬咖啡脱气更快，但不同咖啡样品的孔径分布与脱气行为并无关联。随着含水量增加而变硬的咖啡豆硬度可能对脱气有影响。尽管脱气行为不同，但空气冷却和水淬冷却的咖啡在大多数香气化合物上表现出相似的稳定性。然而，含水量增加的咖啡中三硫化二甲基的变化情况有所不同。这表明硫醇氧化速率更高，这一因素被认为与新鲜度属性更快丧失有关。
