DISKRIMINASI AROMA KOPI ROBUSTA DENGAN VARIASI SUHU ROASTING MENGGUNAKAN ELECTRONIC NOSE YANG TERKORELASI DENGAN GAS CHROMATOGRAPHY MASS SPECTROMETRY; DISCRIMINATION OF ROBUSTA COFFEE AROMA WITH VARIATION OF ROASTING TEMPERATURE USING ELECTRONIC NOSE CORRELATED WITH GAS CHROMATOGRAPHY MASS SPECTROMETRY

YESIANA ARIMURTI, Kuwat Triyana

2014 | Disertasi | PROGRAM STUDI S-2 FISIKA

The quality of coffee is strongly affected by its aroma, so that instrument for aroma testing is necessary especially for quality control. In this research, coffee aroma was tested using electronic nose and then correlated to gas chromatography mass spectrometry (GC-MS). The green beans of robusta coffee (coffea canephora var.robusta) originated from Sumatra (processed with wet method) and Kulon Progo (processed with dry method) were used as testing sample. The roasting temperature was varied to be 180 °C, 195 °C, and 210 °C, while the roasting time was set to be constant at 20 minutes. Each temperature variation resulted light, medium and dark roasted coffee respectively. After the roasting process, the coffee beans were grounded using coffee grinder. The response pattern of each gas sensors of the electronic nose to ground coffee aroma was extracted using two methods; i.e. gradient multiplied by signal peak and average value. The principle component analysis (PCA) was applied to discriminate the aroma of ground coffee with varied roasting temperature. As a result the robusta coffee from Sumatra with three varied roasting temperature gave the percentage of variance as 99.60% for gradient feature extraction method and 97.01% for average value feature extraction method. On the other hand, percentage of variance for robusta from Kulon Progo with three varied roasting temperature is 99.29% for gradient feature extraction method and 99.18% for average value. From the GCMS analysis, it is clear that more aromatic compounds detected when the roasting temperature increase. It is correlated with the discrimination result using electronic nose. In the future, the electronic nose may be applied in coffee industry for quality control during process

Kata Kunci : kopi robusta; aroma; electronic nose; GC-MS