Abstract

To improve the storage method of Kimchi, optimum ripening Kimchi for an irradiation treatment(the time of around 0.3% in total acidity of Kimchi) was irradiated by doses of 1, 2, 3 kGy with Co-60 ${\gamma}-radiation$ and stored at $10^{\circ}C$. Total aerobic bacteria increased in the beginning of storage and then decrease slowly as the number of total lactic acid bacteria increased. Total lactic acid bacteria initially loaded by $10^8\;cells/ml$ in Kimchi shortly after irradiation reduced to $10^4-10^6\;cells/ml$ with 1-3 kGy doses and decreased gradually through the whole storage period. The initial load of yeast, $10^3\;cells/ml$, increased steadily during Kimchi storage and led to more than $10^4\;cells/ml$ after 30 days of storage. While it maintained tha the load in 2-3 kGy irradiated groups after 30 days of storage was less than that at the beginning of storage. pH, acidity and volatile acid in the nonirradiated group were 4.0, 0.7% and 0.06%, respectively at the 15th day after storage, but at the 30th day after storage, 2-3 kGy irradiated groups showed different values, 4.1, 0.58-0.63%, and 0.04-0.05%, respectively. The texture(firmness) of Kimchi reduced along with storage time, and 2 kGy irradiated group proved most favourable in its texture during storage. In the sensory evaluation of Kimchi, nonirradiated group was inedible after 15 days of storage, whereas 2-3 kGy irradiated groups could proling the storage-life of Kimchi over 2 times compared with the nonirradiated Kimchi, showing the good sensory quality even after 30 days of storage.

김장김치 제조방법에 따라 김치를 담금 후 $10^{\circ}C$에서 저장하였다. 김치의 방사선 살균을 위한 최적 숙성기는 적정 산도가 0.3% 내외 일 때 였고, 포장은 PE/Nylon 접합봉지 사용구 보다 PVC원통형 용기에 상부를 유리판으로 눌러놓은 상태의 것이 품질 면에서 우수하였다. 미생물 생육시험에서 전 젖산균은 방사선조사 직후 비조사구는 $10^8\;cells/ml$이었으나 1-3 kGy조사로서 2-4 log cycles감소되었고 전 저장기간을 통해 생육이 억제되었다. 효모 및 곰팡이도 2-3 kGy 조사구는 저장 30일 후에도 저장 초보다 낮았다. 이화학적 특성 시험에서 특히 산도는 비조사구가 저장 15일 에 0.7-0.8% 정도였으나, 2-3kGy 조사구는 저장 30일에도 0.5-0.6%로 낮았다. 김치조직 변화도 저장기간의 경과와 함께 2kGy 조사구가 가장 우수하였다. 관능검사에 의한 종합적 품질평가에서는 비조사구는 저장 15일 이후부터 식용 부적합 하였으나, 2-3 kGy 조사구는 저장 30일 이후에도 양호한 품질을 보여 비조사구에 비해 2배 이상의 저장성을 연장할 수 있었다.

Keywords

• Shelf life of Kimchi;
• Co-60 ${\gamma}-radiation$;
• total lactic acid bacteria;
• acidity;
• sensory evaluation