Perubahan Profile Waktu dan Suhu saat Meroasting Kopi

EFFECTS OF DIFFERENT TIME-TEMPERATURE PROFILES ON COFFEE PHYSICAL AND CHEMICAL PROPERTIES

Green coffee beans provide neither the characteristic aroma nor the taste of a cup of coffee. To reveal their flavour, green coffee beans need to be roasted. Roasting is one of the most important steps in coffee processing that leads to the development of the desired aroma, taste, and color of the final brewed product. In general, the use of roasting temperature of greater than 200oC is required in order to result in desirable chemical, physical, structural, and sensorial changes in the coffee beans (Schenker 2000; Schenker et al. 2002; Baggenstoss et al. 2008).

The time and temperature conditions applied during roasting have a major impact on the physical and chemical properties of roasted coffee beans. Geiger et al. reported that CO2, a by-product formed due to Strecker reactions and the degradation of organic compounds, increased greatly towards the end phase of a high-temperature-short-time process (260oC, 170 s), while the CO2 formed was much lower when a low-temperature-long-time (228oC, 720s) process was employed (Geiger et al. 2005). Schenker et al. found that roasting process that involved a ramping temperature profile (150 to 240oC in 270 s; 240oC for 55 s) resulted in the formation of a greater quantity of aroma volatiles than a low-temperature-long-time process (isothermal heating at 220oC for 600 s) (Schenker et al. 2002). Baggenstoss also reported that high-temperature-short-time roasting led to beans of lower density, higher volume, less roast loss, and lower moisture content as compared to the low-temperature-short time process (Baggenstoss et al. 2008). Lyman et al. roasted green coffee beans under various process conditions to study the effect of roasting on brewed coffee (Lyman et al. 2003). Using a medium roast process (6.5 min to the onset of the first crack and 1.0 min to the onset of the second crack), Lyman et al. observed that coffee of balanced taste and aroma with citrus flavour was produced. However, using the so-called “sweated process” (4.5 min to the first crack and 6.5 min to the second crack), coffee beans of non-uniform bean color with “sour, grassy, and underdeveloped” were resulted. In comparison, the “baked process” (11 min to the first crack and 18 min to the second crack) produced coffees that were “flat, woody with low brightness and acidity” (Lyman et al. 2003). Based on the these observations, one can conclude that the quality of roasted coffee does not solely depend on the physical parameters at the start and end point of roasting, but rather it is dependent on the time-temperature conditions applied during the roasting process. 

Source : Physicochemical Changes of Coffee Beans During Roasting

JAVA PREANGER COFFEE ADDICT

Fadillah Satria

 

FTIP TMIP UNPAD

fadilprojectkopi@gmail.com