Abstract
The garlic juices were 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 volume. The concentrated juices were kept at $4^{\circ}C\;or\;25^{\circ}C$ for 60 days and the changes of bacteria and color were monitored every 10 days. Flavors of the raw garlic juices, concentrated garlic juices, and garlic powder by hot-air drying were analyzed monthly using GC and GC/MS. The CFUs/mL of mesophilic and psychrotrophic bacteria in the garlic juice concentrated at $90^{\circ}C$ were lower about 1 to 2 log cycles than those of other concentrated juices. Hunter L, a, and b values in the raw garlic raw juice and the juice concentrated at $-50^{\circ}C$ significantly increased at the beginning of storage, in particular, when they were stored at $25^{\circ}C$. The garlic juice concentrated at $45^{\circ}C$ showed relatively low L value but the juice concentrated at $90^{\circ}C$ showed high a value. The main peaks in chromatograms of volatile components identified by GC/MS were 3,3'-thiobis-1-propene, di-2-propenyl disulfide, 3-(methylthio)-1-propene in the raw garlic juice and the concentrated juices, and the juices concentrated at $45^{\circ}C\;or\;-50^{\circ}C$ showed relatively high preservation of garlic flavor.
마늘즙의 농축방법에 따른 저장 안정성을 비교하기 위하여 $90^{\circ}C$ 가열농축, $45^{\circ}C$ 감압가열농축, $-50^{\circ}C$ 동결 농축을 통해 농축액을 제조하고 이를 $4^{\circ}C$와 $25^{\circ}C$에서 보관하면서 마늘 농축액의 물리적 특성 및 미생물, 색도를 분석하였고 GC와 GC/MS를 이용하여 향기성분의 변화를 측정하였으며 또한 열풍건조로 마늘가루를 제조하여 향기성분을 측정하였다. 저장기간에 따른 미생물수의 변화는 중온성균과 저온성균의 CFU/mL 모두가 $90^{\circ}C$ 가열농축액에서는 다른 농축액보다 $1{\sim}2log\;cycle$ 이상 낮은 값을 보였으며, 색도는 마늘즙 원액과 $-50^{\circ}C$ 동결농축액에서 L, a, b 값이 저장 초기에 뚜렷하게 증가하였고 $4^{\circ}C$ 저장시보다 $25^{\circ}C$ 저장시에 크게 증가하였다. 또한 $45^{\circ}C$ 감압가열농축액은 대체로 낮은 L값을 보였고, $90^{\circ}C$ 가열농축액은 높은 a값을 보였다. GC-MS에 따른 향기성분 분석에서는 3,3'-thiobis 1-propene, di-2-propenyl disulfide, 3-(methylthio)-1-propene이 마늘즙 원액과 농축액 모두에서 가장 높게 나타났으며, 열풍건조한 마늘가루에 비해 마늘농축액이 향기 성분 보유력이 좋은 것으로 나타났다.