Abstract
The juice of garlic (Euichun variety) was extracted and concentrated by heating at 90$^{\circ}C$, by using a rotary vacuum evaporator at 45$^{\circ}C$, or by freezing at -50$^{\circ}C$ until the volume was reduced to 70% of the original's. The concentrated garlic juice was packed into 15 ml test tubes wrapped with aluminum foil and kept at 4$^{\circ}C$ or 25$^{\circ}C$ for 60 days. Changes of browning, microbiological and sensory characteristics of the concentrated garlic juices were monitored every 10 days. The specific gravity and viscosity of the prepared juices decreased in the juices concentrated at 90$^{\circ}C$, 45$^{\circ}C$ and -50$^{\circ}C$ in order. Browning of the concentrated garlic juices was slower during the storage at 4$^{\circ}C$ than at 25$^{\circ}C$. Browning occurred rapidly in the juice concentrated at 45$^{\circ}C$ during the storage, especially at 25$^{\circ}C$. The numbers of mesophilic and psychrotrophic bacteria in the juices did not increase significantly during the storage, which means the garlic juices had good shelf-life. The CFUs/ml of garlic juice concentrated at 90$^{\circ}C$ were lower about 1 to 2 log cycles than those in other concentrated juices. The juice concentrated at 90$^{\circ}C$ showed the weakest garlic odor and the strongest cooked odor among the juices. The juice concentrated at -50$^{\circ}C$ had the freshest odor, especially stored at 4$^{\circ}C$, but the juice concentrated at 90$^{\circ}C$ had lowest score in fresh odor. Brown color was dark in the juice concentrated at 45$^{\circ}C$ and green color of all the juices did not change significantly during the storage.
마늘(예천종)을 착즙하여 9$0^{\circ}C$에서 가열농축, 45$^{\circ}C$에서 감압가열농축, -5$0^{\circ}C$에서 동결농축하여 마늘즙 원액 부피의 70%농축하여 마늘 농축액을 제조하였다. 제조한 농축액과 마늘즙 원액을 15 ml 시험관에 담아 알루미늄 호일로 싸서 4$^{\circ}C$와 $25^{\circ}C$에서 60일 동안 저장하면서 10일 간격으로 갈변도와 미생물, 관능적 특성 등의 변화를 살펴보았다. 마늘 농축액의 비중과 점도는 9$0^{\circ}C$, 45$^{\circ}C$ 그리고 -5$0^{\circ}C$ 농축액 순으로. 감소하였다. 저장기간 동안 4$^{\circ}C$ 저장시에 $25^{\circ}C$ 저장시보다 다소 갈변화 정도가 느리게 나타났으며, 45$^{\circ}C$ 감압 농축액은 4$^{\circ}C$와 $25^{\circ}C$저장 모두에서 갈변화가 많이 진행되었고 특히 $25^{\circ}C$ 저장시에는 현저하게 높은 갈변도를 보였다. 저장기간에 따라 중온성균 수와 저온성균 수는 모두 크게 증가하지 않아 농축액의 저장성이 양호함을 알 수 있었으며, 9$0^{\circ}C$ 가열농축액은 다른 농축액보다 CFU/ml가 1-2 log cycle 이상 낮은 값을 보였다. 관능검사에서는 9$0^{\circ}C$ 가열농축액의 마늘냄새가 가장 약하게 나타났으며 익은 냄새는 9$0^{\circ}C$ 가열농축액이 마늘즙 원액이나 다른 농축액에 비해 유의적으로 강하게 나타났다. 신선한 냄새는 마늘즙 원액과 -5$0^{\circ}C$농축액에서 강하게 나타났고, 특히 4$^{\circ}C$ 저장시 신선한 냄새가 강하였으며 9$0^{\circ}C$ 농축액에서는 현저히 낮은 값을 나타내었다. 갈색은 45$^{\circ}C$ 감압농축액에서 강하게 나타났으며 녹색은 저장온도, 저장기간에 따른 뚜렷한 변화가 없었다.