Actively Controlled High Carbon Dioxide Concentration Container for Improved Preference and Preservation of Kimchi, a Korean Fermented Vegetable

Abstract

Container system to actively keep modified atmosphere of high carbon dioxide concentration by automated control was designed and tested to store kimchi, a Korean fermented vegetable at high sensory preference for long time period. The system was constructed with a 10 L stainless steel container with plastic cover installed with quick-connecting and check valves. Hypobaric vacuumizing from the vacuum pump and carbon dioxide injection from the carbon dioxide cylinder were combined or used in a programmed automatic mode timely in accordance with the progress of kimchi fermentation. Two storage tests were conducted: one at chilled temperature of 10 °C and the other of storage at 10 °C followed by a higher temperature of 25 °C. The container was filled initially with 8 kg of kimchi (salt content of 2.6-2.7%), closed with a cover and flushed with carbon dioxide. The process of repetitive vacuumizing/carbon dioxide injection reached the internal carbon dioxide partial pressure higher than 0.9 atm. During the storage, carbon dioxide gas was injected into the container for 15 seconds every 12 hours or every 24 hours depending on the kimchi ripening progress through the carbon dioxide supply line to supplement the carbon dioxide that is dissolved into the kimchi or lost. A container simply closed without vacuumizing and carbon dioxide injection was submitted to the same storage and opening/closing conditions for the purpose of control. During the storage, the containers were opened and closed intermittently often with taking out some kimchi to simulate consumer behavior, and then the same procedure of hypobaric treatment and carbon dioxide injection was followed for the CO2-controlled one. Container atmosphere and product quality were measured through the storage. Compared to the control container, the CO2-controlled container system improved the sensory flavor of kimchi in the whole storage period and inhibited the growth of spoilage yeasts with the extended storage at both the chilled and abuse temperatures.