The Effects of Fermentation Temperature on the Physico-chemical Characteristics of the Korean Cabbage, Kimchi
Jung-hwan Oh
Department of Food Science and Nutrition,
Graduate School Pusan National University
Abstract
In the present study, we examine...
The Effects of Fermentation Temperature on the Physico-chemical Characteristics of the Korean Cabbage, Kimchi
Jung-hwan Oh
Department of Food Science and Nutrition,
Graduate School Pusan National University
Abstract
In the present study, we examined the effects of fermentation temperature on the physico-chemical characteristics of kimchi stored at 5℃, 10℃, 15℃, and 20℃. These effects were compared with those of kimchi fermented at a controlled-temperature¹. Furthermore, we also conducted another experiment storing kimchi at -1℃, and examined the chemical, microbial, and sensory properties of kimchi stored at -1℃ in relation to the extension of the shelf life of kimchi.
Changes in the pattern of pH and acidity of kimchi fermented at different temperature were differed, revealing a rapid change with a higher fermentation temperature. pH of kimchi decreased to 4.0±0.1 and then stabilized. Acidity of kimchi increased continuously during the entire fermentation periods. However, pH of kimchi stored at -1℃ gradually decreased to 4.39, and its acidity increased to 0.53% in the 12th week. Optimal ripening time for kimchi in terms of the favorable edible quality was strongly associated with pH and acidity, which was found to be 4.3±0.1 and 0.7±0.1%, respectively. According to these results, kimchi fermented at -1℃ did not reach the stage for properly ripened even after 12 weeks of storage. The duration of kimchi maintained the optimal ripening stage, acidity 0.7±0.1%, were 7 days for 5℃, 4 days for 10℃ , 3 days for 15℃, 1 day for 20℃, and 8 days for the controlled-temperatures. Growth of Leuconostoc sp. and Lactobacillus sp. were strongly associated with the fermentation temperature. Leuconostoc sp. of kimchi fermented at 5℃, 10℃, 15℃, 20℃, and at controlled-temperatures achieved the maximum (108-9CFU/mL) at the day of 20th, 12th, 9th, and 2nd of fermentation. But the maximum concentration for Leuconostoc sp. observed in kimchi stored at -1℃ was below 108 CFU/mL until the 12th week of storage. Lactobacillus sp. of the kimchi fermented at 5℃, 10℃, 15℃, 20℃, and at controlled-temperatures reached a plateau (108 CFU/mL) at 20th, 12th, 9th, and 4th respectively. Nevertheless, Lactobacillus sp. of the kimchi stored at -1℃ were lower than 107 CFU/mL throughout the 12th week. The highest scores for the overall acceptability observed from kimchi at different fermentation temperatures were 7.2 (15th day at 5℃), 6.2 (8th day at 10℃), 6.0 (6th day at 15℃), and 5.8 (2nd day at 20℃). In the kimchi fermented at a controlled-temperature, the score for the fresh kimchi was higher than that of well fermented kimchi. This might be due to high fermentation temperature, which is 23℃ for 25 hrs. Lactic acid bacteria might be over grown. The score of 5.9 in kimchi stored at -1℃ were the highest during the entire storage period. On week 12, the reducing sugar contents of kimchi stored at -1℃ decreased to 21%. The ascorbic acid amounts and antioxidant capacity (TEAC) of kimchi stored at -1℃ decreased to 13% and 17% during the 12-week fermentation period, respectively. But the changes were not significant.
In conclusion, lower fermentation temperature (5℃) is better for kimchi taste as well as extends the shelf-life of kimchi. The temperature -1℃ for kimchi fermentation is found to be an undesirable temperature because kimchi taste was not developed due to delayed fermentation process.
1. Pre-set at 23℃ for 25 hours for the fermentation course and -1℃ for the storage course in the kimchi refrigerator (Model HNR2013Q, S Electronics, Korea)
The Effects of Fermentation Temperature on the Physico-chemical Characteristics of the Korean Cabbage, Kimchi
Jung-hwan Oh
Department of Food Science and Nutrition,
Graduate School Pusan National University
Abstract
In the present study, we examined the effects of fermentation temperature on the physico-chemical characteristics of kimchi stored at 5℃, 10℃, 15℃, and 20℃. These effects were compared with those of kimchi fermented at a controlled-temperature¹. Furthermore, we also conducted another experiment storing kimchi at -1℃, and examined the chemical, microbial, and sensory properties of kimchi stored at -1℃ in relation to the extension of the shelf life of kimchi.
Changes in the pattern of pH and acidity of kimchi fermented at different temperature were differed, revealing a rapid change with a higher fermentation temperature. pH of kimchi decreased to 4.0±0.1 and then stabilized. Acidity of kimchi increased continuously during the entire fermentation periods. However, pH of kimchi stored at -1℃ gradually decreased to 4.39, and its acidity increased to 0.53% in the 12th week. Optimal ripening time for kimchi in terms of the favorable edible quality was strongly associated with pH and acidity, which was found to be 4.3±0.1 and 0.7±0.1%, respectively. According to these results, kimchi fermented at -1℃ did not reach the stage for properly ripened even after 12 weeks of storage. The duration of kimchi maintained the optimal ripening stage, acidity 0.7±0.1%, were 7 days for 5℃, 4 days for 10℃ , 3 days for 15℃, 1 day for 20℃, and 8 days for the controlled-temperatures. Growth of Leuconostoc sp. and Lactobacillus sp. were strongly associated with the fermentation temperature. Leuconostoc sp. of kimchi fermented at 5℃, 10℃, 15℃, 20℃, and at controlled-temperatures achieved the maximum (108-9CFU/mL) at the day of 20th, 12th, 9th, and 2nd of fermentation. But the maximum concentration for Leuconostoc sp. observed in kimchi stored at -1℃ was below 108 CFU/mL until the 12th week of storage. Lactobacillus sp. of the kimchi fermented at 5℃, 10℃, 15℃, 20℃, and at controlled-temperatures reached a plateau (108 CFU/mL) at 20th, 12th, 9th, and 4th respectively. Nevertheless, Lactobacillus sp. of the kimchi stored at -1℃ were lower than 107 CFU/mL throughout the 12th week. The highest scores for the overall acceptability observed from kimchi at different fermentation temperatures were 7.2 (15th day at 5℃), 6.2 (8th day at 10℃), 6.0 (6th day at 15℃), and 5.8 (2nd day at 20℃). In the kimchi fermented at a controlled-temperature, the score for the fresh kimchi was higher than that of well fermented kimchi. This might be due to high fermentation temperature, which is 23℃ for 25 hrs. Lactic acid bacteria might be over grown. The score of 5.9 in kimchi stored at -1℃ were the highest during the entire storage period. On week 12, the reducing sugar contents of kimchi stored at -1℃ decreased to 21%. The ascorbic acid amounts and antioxidant capacity (TEAC) of kimchi stored at -1℃ decreased to 13% and 17% during the 12-week fermentation period, respectively. But the changes were not significant.
In conclusion, lower fermentation temperature (5℃) is better for kimchi taste as well as extends the shelf-life of kimchi. The temperature -1℃ for kimchi fermentation is found to be an undesirable temperature because kimchi taste was not developed due to delayed fermentation process.
1. Pre-set at 23℃ for 25 hours for the fermentation course and -1℃ for the storage course in the kimchi refrigerator (Model HNR2013Q, S Electronics, Korea)
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