Effect of mugwort extract on the quality and the changes of chemical compositions of the Chung-kookjang prepared with frozen soybean

청국장제조시 대두원료의 동결과 쑥추출물의 첨가가 품질 및 이화학적 성분변화에 미치는 영향

Effect of freezing of soybean and addition of mugwort on the flavor development and the changes of chemical compositions in Chungkookjang was investigated. The changes in the amount of amino-type N, the activities of ${\alpha}-amylase$ and protease, and the content of volatile compounds were determined during aging of Chungkookjang. During ripening, a little higher protease activity was detected in Chungkookjang made of frozen soybean than in that made of non-frozen soybean. However, the profile of ${\alpha}-amylase$ activity of Chungkookjang made of frozen soybean was very similar to that of Chungkookjang made of non-frozen soybean. The amount of amino-type N increased gradually with the ripening period and decreased after 21 days of ripening. The amount of amino-type N was slightly higher in Chungkookjang made of frozen soybean than in that made of non-frozen soybean. Addition of mugwort had little effect on the enzyme activities and the amino-type N content. The mugwort added in Chungkookjang reduced the production of cis-3-hexenol which is responsible for the unpleasant odor, and freezing of soybean enhanced the production of 2, 6-dimethyl pyrazine which is contribute to the taste. According to sensory evaluation, flavor was the highest after the 14 days of ripening and addition of mugwort increased significantly the flavor in both Chungkookjang prepared with frozen soybean and Chungkookjang with non-frozen soybean. However, the effect of freezing of soybean on the flavor was not significant.

청국장제조시 대두원료의 동결과 쑥추출물의 첨가가 청국장의 숙성에 미치는 영향을 검토하고자 청국장 숙성과정중의 아미노태 질소, ${\alpha}-amylase$ activity, protease activity, 향기성분의 변화와 관능특성을 조사하였다. 청국장 숙성과정중 protease activity는 동결처리한 대두를 사용한 청국장에서 약간 높았던 반면 ${\alpha}-amylase$ activity는 차이가 없었다. 아미노태 질소량은 전체적으로 동결처리한 청국장이 다소 높은 값을 보였으며 숙성기간이 길어짐에 따라서 점차적으로 증가하다가 숙성 21일후 감소하였다. 쑥추출물의 첨가에 따른 효소활성의 유의적인 차이는 없었다. 쑥추출물의 첨가에 의해 불쾌취원인의 하나로 알려진 cis-3-hexenol의 생성량이 감소되었고, 동결에 의해 항기물질인 2,6-dimethyl pyrazine의 생성이 촉진되었다. 관능검사 결과 14일 숙성된 청국장이 전체적으로 가장 높은 선호도를 보였으며, 쑥추출물이 첨가된 경우에는 대두의 동결여부에 관계없이 쑥이 첨가되지 않은 경우보다 flavor가 유의적으로 우수하였으나 대두원료의 동결에 따른 차이는 감지되지 않았다.