Abstract
Effect of storage temperature and packing method on the changes in pH, acidity, the levels of lactic acid bacteria, volume expansion of packages and the colorness during the fermentation of kakdugi (diced radish kimchi) were investigated. The fermentation characteristics were greatly influenced by the temperature. The pH of kakdugi fermented at 15$^{\circ}C$ was 4.10 at 3 days, while the pH of kakdugi fermented at $0^{\circ}C$ was 4.03 at 18 days. The acidity of kakdugi fermented at $0^{\circ}C$ very slowly increased compared to that of the kakdugi fermented at 15$^{\circ}C$, 1$0^{\circ}C$ or 5$^{\circ}C$. The required days to reach the acidity of 0.6% (optimally ripened state) were 6 days at 15$^{\circ}C$, 7 days at 1$0^{\circ}C$, 18 days at 5$^{\circ}C$ and 30 days at $0^{\circ}C$. Despite of different fermentation temperature, the numbers of Leuconostoc sp. in optimally ripened kakdugi were similar. However, Lactobacillus sp. in kakdugi fermented at $0^{\circ}C$ was the smallest in number. Also, the volume expansion of aluminum pack was the lowest in kakdugi fermented at $0^{\circ}C$. Both pH and acidity of the kakdugi fermented in different packing condition did not show any difference at 1$0^{\circ}C$ for 20 days, however, the color of the kakdugi was affected by a packing method. Aluminium laminate package in which Ca(OH)$_2$ Pack stuck inside resulted in decolorization of kakdugi compared with aluminum package without Ca(OH)$_2$ pack or plastic jar. It showed the lowest redness and the highest lightness and yellowness. These results indicated that fermentation at $0^{\circ}C$ could increase storage period of kakdugi with minimum growth of Lactobacillus sp., and plastic jar might relieve the problem of volume expansion and decolorization of kakdugi.
발효온도과 포장방법이 깍두기의 저장기간, 젖산균수 및 깍두기 포장물의 부피변화에 미치는 영향을 측정하였다. 발효온도가 높을수록 pH가 급격히 감소하였으며, 적숙기인 산도0.6%에 도달하는데 걸리는 시간은 $0^{\circ}C$에서 30일로 15$^{\circ}C$에서의 6일에 비해 5배 정도 저장성이 높았다. 발효온도에 따른 Leuconostoc sp. 젖산균의 수는 큰 차이가 없었으나 Lactobacillus sp. 젖산균의 수는 $0^{\circ}C$에서 발효시킨 깍두기에서 가장 적었다. 또한 $0^{\circ}C$에서 발효시킨 깍두기에서 알루미늄 파우치 의 부피팽창이 가장 적었다. 플라스틱 병과 알루미늄포장지에서 발효한 깍두기는 pH와 산도에서 차이가 없었으며, 가스흡수제(Ca(OH)$_2$)를 넣은 알루미늄포장지에서 발효한 깍두기는 적색도가 낮고 황색도가 높아 깍두기의 색이 탈색되는 것으로 나타났다. 따라서 배추김치에 비해 저장성이 낮은 깍두기의 경우 $0^{\circ}C$에서 발효하는 것이 저장성을 높일 수 있으며 플라스틱 병에서 저장할 경우 포장물의 부피팽창과 깍두기의 탈색을 억제할 수 있어 깍두기의 품질을 향상시킬 수 있을 것으로 보인다.
