Analysis of Characteristics and Aroma Pattern of Powdered Chungkookjang from Hot-Air and Freeze Drying

열풍 및 동결 건조 분말 청국장의 특성 및 향기 패턴 분석

Two types of powdered chungkookjang, were prepared by a hot air-drying process, and the freeze-drying, and composition and aroma patterns were examined. The fresh chungkookjang was composed of 53.8% moisture, while the hot air-dried and freeze-dried powdered chungkookjang contained 5.2% moisture, $39.3{\sim}39.4%$ crude protein, $18.6{\sim}18.7%$ crude lipid, $4.7{\sim}5.0%$ crude ash, and $31.7{\sim}32.2%$ carbohydrate. The pH of the each powered chungkookjang was similar, ranging from 6.5 to 6.7. The freeze-dried powdered chungkookjang showed the highest lightness (67.30), yellowness (59.37) while the highest redness (43.1) was observed in the hot air-dried chungkookjang. Each chungkookjang was analysed by an electronic nose with metal oxide 12 sensors and SPME-GC/MS. The response by the electronic nose was analysed by principal component analysis (PCA). The proportion of the first principal component was 90.47%, suggesting that each aroma pattern of the prepared chungkookjang was discriminated. SPME-GC/MS was used to identify the pyrazines. The percentage of pyrazines observed in the fresh chungkookjang, freeze-dried powdered chungkookjang, and hot air-dried powdered chungkookjang was 6.6, 3.8 and 15.9%, respectively. A higher overall preference was obtained from the hot air-dried powdered chungkookjang than with the freeze-dried powdered chungkookjang.