Bacrillus sp. b01 균주를 사용한 청국장 제조 시 yucca 추출물의 첨가가 청국장의 숙성에 미치는 영향을 검토하고자 청국장 숙성 과정중의 아미노태 질소, 암모니아태 질소, amylase 활성, protease 활성, 유기산 및 향기성분의 변화를 조사하였다. 청국장 숙성 중 yucca 첨가구에서 아미노태 질소 함량은 증가하였으며, 암모니아태 질소는 감소하였다. Amylase 활성은 yucca 첨가구들이 대조구와 비교 시 높게 나타났지만 yucca 추출물을 1 mg/g 첨가 시 감소함을 보였다. Protease 활성은 yucca 추출물 첨가구가 무 첨가구보다 다소 높게 나타났다. 청국장에서의 유기산을 citric acid, acetic acid, malic acid가 검출되었고, yucca 첨가구에서 대조구에 비하여 그 함량이 다소 높았다. 또한 yucca 추출물 첨가 시 2,5-dimethylpyrazine과 2,6-dimethylpyrazine은 증가하였고, tetramethylpyrazine이 숙성 기간 중 감소함을 보였다. 관능검사에서도 yucca 추출물 0.5 mg/g을 첨가시 무 첨가구보다 유의적으로 맛과 향이 우수하였다.
This study was carried out to investigate the effect of yucca extract on the flavor development in Chungkookjang fermented by Bacrillus sp. b01. The changes in the contents of amino-type N, ammonia type N, volatile compounds and organic acids, and those in the activities of ${alpha}-amylase$ and protease were also determined with aging period. The amount of amino-type N increased gradually with time and was slightly higher in Chungkookjang containing yucca extract than in control. The content of ammonia-type N in Chungkookjang decreased by the addition of yucca extract. During aging, a little higher amylase activity was detected in Chungkookjang containing yucca extract. However, the amylase activity was the lowest in Chungkookjang containing 1 mg/g of yucca extract. The protease activity was slightly higher in Chungkookjang containing yucca extract. The organic acids, such as citrate, acetate, malate, fumarate, and succinate, were detected. The yucca extract reduced the production of tetramethylpyrazine which was responsible for the unpleasant odor, but enhanced the production of 2,5-dimethylpyrazine and 2,6-dimethylpyrazine which contributed to the taste. Sensory evaluation showed that the addition of yucca extract of 0.5 mg/g significantly improved the flavor and taste of products.
