Abstract
The effects of temperature variations during storage, pasteurization on the quality of orange juices were investigated. To evaluate the quality of orange juices pasteurized at 75, 85 and $95^{\circ}C$ for 15 sec, microbial and physicochemical measurements and sensory evaluations were conducted during storage at 10, 20 and $30^{\circ}C$ for 32days. Color(lightness) and contents of vitamin C and sucrose were not changed at $10^{\circ}C$, but decreased at $20^{\circ}C$ and $30^{\circ}C$ as the storage time was increased. The pasteurization temperature had a little effect on the color and the contents of vitamin C and sucrose. Furfural contents were apparently increased as the storage period extended, but the samples stored at $10^{\circ}C$ had less amounts than the others. On the other hand, the pasteurization temperature did not affect furfural accumulation. Furfural was produced as a result of the degradation of vitamin C and deterioration of the color. The PH values were not changed during the entire storage period, and microorganisms were not detected in most of the samples. The result of sensory evaluation indicated no taste difference between the control and the sample stored at $10^{\circ}C$, but the taste changes were recognized when the samples were stored over 24 and 20 days at $20^{\circ}C$ and $30^{\circ}C$, respectively. Therefore, the storage temperature affected the quality of orange juices more markedly than the pasteurization temperature, and the storage at lower temperature appears to reduce the deterioration of orange juices.
다양한 온도에서 살균과 저장이 오렌지 쥬스의 품질에 미치는 영향을 알아보기 위하여 orange juice$(12^{\circ}Brix)$를 75, 85, $95^{\circ}C$에서 각각 15초간 살균한 뒤 10, 20, $30^{\circ}C$의 incubator에서 32일간 저장하며 미생물, 이화학적 및 관능검사를 실시하였다. Vitamin C와 sucrose함량, 그리고 색은 $10^{\circ}C$ 저장시에 안정성이 우수하였으나, $20^{\circ}C$, $30^{\circ}C$에 저장하였을 때 저장기간이 증가함에 따라 현저한 감소를 나타내었다. 반면, 살균온도에 따른 손실량의 차이는 미약하였다 Furfural은 저장기간이 증가함에 따라 생성량의 급격한 증가를 나타내었으며 $10^{\circ}C$ 저장시 생성량이 가장 적었다. 또한 살균온도에 따른 생성량 차이는 미약하였다. Furfural은 vitamin C가 분해되어 생성되며 색을 어둡게 만들었다. 저장기간동안 오렌지 쥬스의 pH는 일정하게 유지되었으며, 일반세균과 효모, 곰팡이의 검출결과는 음성으로 나타났다. 관능검사 결과 $10^{\circ}C$ 저장시료는 저장 32일까지 대조군과 차이가 없었고, $20^{\circ}C$와 $30^{\circ}C$ 저장시료는 24일과 20일만에 각각 대조군과 차이를 나타내었다. 따라서 오렌지 쥬스의 품질은 살균온도보다 저장온도에 의하여 더 큰 영향을 받으며, 저온저장이 품질변화의 억제에 효과적임을 알 수 있었다.