Application of Physical Gas Absorbers in Manipulating the CO2 Pressure of Kimchi Package.

Physical gas absorption and release of activated carbon or zeolite were used to attain the desired CO2 concentration profile inside a package of kimchi for its dynamic storage and consumption environment. The CO2 adsorption/desorption behavior of different combinations of physical scavengers in the microporous Tyvek sachet was measured at 0, 10 and 20 °C. A combination of highly permeable microporous Tyvek and much less permeable nylon/polyethylene laminate was also examined as a variable to help control the access of CO2 to the physical CO2 absorber. The composition of the absorber and its packing density in the sachet affected the CO2 absorption rate and capacity. Increased zeolite in the Tyvek sachet showed higher CO2 absorption followed by higher CO2 release concomitant with moisture sorption, while activated carbon itself had low CO2 absorption and little subsequent CO2 desorption. Lower temperatures increased the capacity of CO2 absorption and release along with lower CO2 absorption and release rates. A reduction in Tyvek area could decrease the absorption and release rates. An application of a physical CO2 absorber to the kimchi package was tested at 10 °C to show potential for keeping the desired CO2 pressure profile for carbonic cool flavor under tolerable pressure during storage and use. PRACTICAL APPLICATIONS: Physical carbon dioxide absorbers consisting of zeolite and activated carbon inside the gas-permeable sachet can be placed in kimchi packages for time-dependent absorption and release of carbon dioxide, which responds in harmony with the fermentation profile of kimchi. Its practical potential is both to provide a carbonic cool taste of the product and to avoid excessive overpressure in the package through its shelf life when used in kimchi packaging. Its intelligent use may resolve the problem of a dull kimchi taste, which occurs when incorporating calcium hydroxide as the chemical scavenger in the package.

Development of Multifunctional Active Film and Its Application in Modified Atmosphere Packaging of Shiitake Mushrooms.

Agar-based films with multiple functions (CO2 absorption, water vapor absorption, and antimicrobial activity) were developed, tested for their properties, and then applied to the packaging of fresh shiitake mushrooms as an insert label. The films were cast from an agar-based aqueous solution containing a dissolving plasticizer (glycerol), a CO2 absorbent (sodium carbonate [SC] alone or a combination of SC and sodium glycinate [SC-SG]), and a volatile antimicrobial agent (carvacrol [CRV]). The agar of the film matrix is designed to serve as a water vapor absorbent. The multifunctional films tended to have poor mechanical properties, with a hard texture and an opaque and yellowish color. The CO2 absorbent, either SC alone or SC-SG, affected CRV retention and release along with the CO2 and water vapor absorption behavior. Both films (SC-CRV and SC-SG-CRV films) showed good inhibitory effects against Pseudomonas fluorescens and Saccharomyces cerevisiae . SC-CRV film had a higher and faster CO2 absorption property, higher retention and extended release of CRV, and lower and slower water vapor absorption and was assessed to be better suited for use in shiitake mushroom packaging. The packaging in which the SC-CRV film with an appropriate amount of CRV was used as an insert label was able to generate the desired atmosphere and less moisture condensation inside the package, producing the best preservation of quality in terms of mushroom color, firmness, flavor score, and microbial counts after 6 days of storage at 10°C. A tailored modified atmosphere packaging system using multifunctional film would be useful in the preservation of CO2-sensitive fresh commodities.

Model on the microbial quality change of seasoned soybean sprouts for on-line shelf life prediction.

The growth of aerobic bacteria on Korean seasoned soybean sprouts was modelled as a function of temperature to estimate microbial spoilage and shelf life on a real-time basis under dynamic storage conditions. Counts of aerobic bacteria on seasoned soybean sprouts stored at constant temperatures between 0 degrees C and 15 degrees C were recorded. The bootstrapping method was applied to generate many resampled data sets of mean microbial plate counts that were then used to estimate the parameters of the microbial growth model of Baranyi and Roberts. The distributions of the model parameters were quantified, and their temperature dependencies were expressed as mathematical functions. When the temperature functions of the parameters were incorporated into differential equations describing microbial growth, predictions of microbial growth under fluctuating temperature conditions were similar to observed microbial growth.