방사선 병용기술을 이용한 한국형 우주김치 개발

Abstract

This study was conducted to evaluate the combined effects of additives (A), N₂-packaging (N₂), mild heating at 60℃ (HT) and gamma irradiation of 25 kGy (IR) at frozen state (F) on the shelf stability and quality of Kimchi during storage at 35℃ for 30 days. 1. Kimchi treated with heat and gamma irradiation This study was conducted to evaluate the combined effect of heat and gamma-irradiation on the shelf-stability and quality of kimchi during storage at 35℃. The optimum condition for the heat treatment of kimchi was considered at 60℃ for 30 min. Irradiation after heat treatment was effective to inhibit the growth of microorganisms and prevent the quality change of kimchi during storage. Specially, microorganisms of kimchi co-treated with heat and 25 kGy-irradiation were not detected and sensory scores of that were the highest after storage at 35℃ for 14 days. Therefore, combination treatment of heat and irradiation was considered as the effective method to improve the shelf-stability of kimchi in the accelerated condition. 2. Kimchi treated with N₂-packaging, mild heating, and gamma irradiation This study was conducted to evaluate the combined effects of N₂-packaging (N₂), mild heating at 60℃ (HT) and gamma irradiation of 25 kGy (IR) on the shelf stability and quality of Kimchi during storage at 35℃ for 30 days. Total microbes including lactic acid bacteria were sterilized perfectly by the combination treatment of HT-IR or N₂-HT-IR, and the acidity of Kimchi was not changed during storage. Irradiation softened textural property of Kimchi. However, combination of N₂-packaging with heating and irradiation retarded this softening of Kimchi by high dose irradiation. Organoleptic qualities were improved by the combination treatment during the storage period. 3. Kimchi treated with N₂-packaging, mild heating, and gamma irradiation under freezing temperature The present study was conducted to evaluate the effect of irradiation temperature on the shelf stability and quality of Kimchi during storage at 35℃ for 30 days. Kimchi samples were N₂-packaged and heated at 60℃ and then gamma irradiated at 25 kGy under various temperatures (room temperature, ice, dry ice, and liquid nitrogen). In the results of microbial, pH and acidity analysis, combination treatment of heating and irradiation was able to sterilize microbes in Kimchi regardless of irradiation temperature. When Kimchi was irradiated under frozen temperatures, especially dry ice, the softening of texture and the deterioration of sensory quality of Kimchi were reduced. Also, ESR signal intensities were weakened as the decrease of irradiation dose and temperature. 4. Kimchi treated with additives, N₂-packaging, mild heating, and gamma irradiation under freezing temperature 4.1. Effect of calcium products treatment The effect of calcium products treatment on the inhibition softening of irradiated Kimchi by 25 kGy was investigated. The optimal addition rate of calcium products (calcium lactate: C.L, calcium acetate: C.A, calcium chloride: C.C, calcium: C) were determined to 0.01% after sensory evaluation, respectively. The texture of irradiated (25 kGy) Kimchi samples added with all calcium products were ranked as follows: C.L Kimchi > C.C Kimchi > C Kimchi > C.A Kimchi with significant differences of P < 0.05. 4.2. Effect of vitamin C and calcium lactate addition The effect of vitamin C and calcium lactate addition on the softening inhibition of high dose irradiated Kimchi was investigated. Optimal addition rate of vitamin-c and all calcium products (calcium lactate: C.L, calcium acetate: C.A, calcium chloride: C.C, calcium: C) weredetermined to 0.3% and 0.01%, respectively. The texture, taste, flavor, and overall acceptance of irradiated (25 kGy) Kimchi samples added with all calcium products were ranked as follows: C.L Kimchi > C.C Kimchi > C.A Kimchi > C Kimchi with significant differences of P < 0.05. The hardness of irradiated (25 kGy) Kimchi samples added with vitamin C or C.L were higher than that of control and unadded during stroage. The hardness of vitamin C+C.L (ADD), N₂-packaging (N₂), mild heating at 60℃ (HT), Freezing at -70℃ (F) and gamma irradiation of 25 kGy (IR) treated Kimchi was higher than that of control and unadded combined treatment during storage 30 days at 35℃. 4.3. Effect of paprika color and Kimchi flavor This study was conducted to evaluate the combination effects of paprika color and Kimchi flavor on the improvement of sensory quality of irradiated sterilization Kimchi during storage at 35℃ for 30 days. In our previous results, the total microbes, lactic acid bacteria contents of N₂-HT (60℃)-F (-70℃)-IR (25 kGy) treated with Kimchi was perfectly sterilized. Also, sensory quality of N₂-HT-F-IR treated with Kimchi was higher than that of all treatments (Control, HT, HT-IR, N₂-HT-IR). However, color and taste acceptance of Kimchi was still decreased by irradiation. Meanwhile, at this study, total microbes, lactic acid bacteria contents of A (paprika color, Kimchi flavor)-N₂-HT-F-IR (25 kGy) treated with Kimchi was not detectable, decrease of color, taste, overall acceptance on irradiated Kimchi could effectively controll during all storage times.