Changes in Methyl Pyrazines of Cocoa Beans during Microwave Roasting

Microwave Roasting에 의한 Cocoa Bean의 Methyl Pyrazine류의 변화

Flavor components focused on the methyl pyrazines(2,3-dimethyl pyrazine, 2,3,5-trimethyl pyrazine, tetramethyl pyrazine) of microwave-roasted cocoa beans were determined and compared with those of conventionally-roasted cocoa beans. Domestic microwave oven was modified to design the microwave roasting system. Temperature measurement technique using thermocouple probes was developed to determine the center temperature of cocoa beans during microwave roasting. Microwave roasting was carried out under two different conditions. Under the first condition, roasting time was fixed to 30 min, while roasting temperature was varied to $110^{\circ}C,\;120^{\circ}C,\;130^{\circ}C,\;140^{\circ}C,\;and\;150^{\circ}C$ Under the second condition, roasting temperature was fixed to $130^{\circ}C$, while roasting time was varied to 5 min, 10 min, 20 min, and 30 min. Conventional roasting was done at $120^{\circ}C$ for 15 min as a reference. Amount of methyl pyrazines and their ratios were influenced by microwave roasting temperature and roasting time. The most suitable methyl pyrazine ratio of cocoa beans was obtained at $140^{\circ}C$ for 30 min of microwave roasting.

Coca bean을 마이크로파로 roasting하고 그 향기성분의 변화를 methyl pyrazine류를 중심으로 살펴보고 이를 상법으로 roasting한 경우와 비교해 보았다. 전자렌지를 개조하여 마이크로파 roasting system을 설계하여 실험에 사용하였고 열전쌍을 이용한 온도측정법으로 cocoa bean의 품온을 측정하였다. 마이크로파 roasting은 roasting 시간을 30분으로 고정하고 온도를 110, 120, 130, 140 및 $150^{\circ}C$로 변화시킨 경우와 roasting 온도를 $130^{\circ}C$로 고정하고 roasting 시간을 5, 10, 20 및 30분으로 변화시킨 경우로 구분하여 행하였다. 상법 roasting은 $120^{\circ}C$에서 15분간 실시하였다. Methyl pyrazine 류의 함량과 함량비는 마이크로파 roasting 온도 및 rosting 시간에 영향을 받았으며 적정한 methyl pyrazine류의 비는 $140^{\circ}C$ 30분 roasting에서 얻을 수 있었다.