Development of Odor-Reduced Korean Traditional Cheonggukjang Added with Job's Tears

냄새저감형 율무청국장 제조에 관한 연구

This study was performed to develop an odor-reduced Korean traditional Cheonggukjang (fermented soybean paste) by adding Job's tears to Cheonggukjang made with soybean (control) only. The study included the determination of best addition percentage of Job's tears versus soybean, sensory evaluation, and aroma patterns and its components as well as proximate composition analyses of Cheonggukjang. Job's tears Cheonggukjang (CAJT) was prepared by inoculating Bacillus subtilis and fermented at $40^{\circ}C$ for 48 hours. Ratios of soybean : Job's tears for Job's tears Cheonggukjang were 1:1, 2:1, 3:1, and 4:1, respectively. In comparison of proximal composition, Job's tears Cheonggukjang was high in moisture and carbohydrates, but low in calorie, fat, protein, ash and amino nitrogen. The pH of CAJT was lower than those of control and conventional Cheonggukjang (CC) sold in the market, and the acidity was the lowest in CC. The color of Job's tears Cheonggukjang appeared the whiter and more yellowish, but less reddish in proportion to contents of Job's tears. The contents of viscous substances were higher in CAJT compared with those of control and CC. The contents of glutamic acid, the major components of viscous substances were lower in CAJT than in control and CC, and the contents of fructose higher in CAJT. The scores of sensory evaluation were the highest in Job's tears Cheonggukjang mixed with soybean : Job's tears=4:1. The aroma pattern of CC analyzed was conspicuously dissimilar to the control and CAJT and also discriminated by electronic nose examination. The pyrazines, volatile compounds peculiar to Cheonggukjang, were found to be lower in CAJT by SPME-GC/MS assay. Additionally, the acetic acid, butanoic acid, and naphthalene causing off-flavor were identified in CC, but not in Job's tears Cheonggukjang. The strength of odor through sensory evaluation was by far the lowest in CAJT among the groups. From the findings, it had shown that Job's tears Cheonggukjang would be produced successfully when the ratio of 4:1 (soybean : Job's tears) is employed. Also, it was proved that appropriate ratio of Job's tears addition makes Cheonggukjang odor-reduced and well accepted by people.

율무의 첨가가 청국장 냄새 저감에 영향을 미치는지 확인하기 위해 대두와 율무의 혼합 비율별 가공 적성 조사 및 적정 배합비 설정, 이에 따른 관능특성 평가, 향기 패턴 및 성분 분석을 실시하였다. 대두만 사용된 대조구와, 대두와 율무를 각각 1:1, 2:1, 3:1, 4:1의 비율로 혼합한 처리구에 Bacillus subtilis 종균을 접종하여 발효시킨 청국장과 재래식 청국장을 실험에 사용하였다. 율무청국장의 열량, 지방, 단백질, 회분, 아미노태 질소의 함량이 대조구보다 낮았으며, 수분과 탄수화물은 높았다. pH는 율무청국장이 상대적으로 낮았고, 색도는 율무의 함량이 높을수록 백색도와 황색도는 높고 적색도는 낮은 경향을 보였다. 점질물 함량은 율무청국장에서 높은 경향을 보였고, 점질물 중의 glutamic acid 함량은 율무청국장이 상대적으로 낮았고 fructose 함량은 상대적으로 높았다. 관능평가 결과 대두와 율무 4:1 처리구의 기호도가 가장 높았다. 대조구와 율무청국장의 향기패턴은 재래식 청국장과 확연하게 달랐으며, 두 처리구는 비슷한 패턴이지만 구별이 가능하였다. 또한 대조구보다 율무청국장에서 pyrazine류 화합물이 적게 동정되어 청국장 냄새가 적게 난다는 것을 확인하였고, 냄새의 강도 관능평가 결과도 율무청국장이 유의적으로 낮았다. 이상에서 율무청국장을 제조할 때 율무의 함량은 20%를 첨가하는 것이 가장 적합하며, 율무청국장은 일반 청국장에 비해 냄새 저감 효과가 있음을 확인할 수 있었다.