Keeping certain level of carbon dioxide concentration along with a desired oxygen concentration in food packages is helpful in preserving a variety of foods, and thus, active packaging technology to control CO 2 has been reviewed here in perspective of optimized package design. For whatever product packages, tailoring interaction among the gas, food product and packaging material is essential for realization of positive role and function of CO 2 : antimicrobial activity, prevention of oxidation, preferred sensory quality, maintenance of package integrity and extension of shelf life.Gas absorbers, emitters or active valves may be applied for this purpose, and commercial products are available in market. However, these active devices should be applied in harmony with food's CO 2 production and dissolution. Elements or factors involved in the design process are examined by looking over scientific literature.Mass balance relationship combined with dissolution equilibration for active food package has been presented to control CO 2 concentration and package wholesomeness in beneficial and desired way. Atmosphere estimation of roasted coffee packages was presented as case study for tackling the task of attaining the desired condition.

We developed a multi-functional agar-based biofilm for fresh produce packaging by modulating its CO 2 absorption and water vapour absorption functions. The film was prepared from solutions containing agar as a matrix and a water vapour absorbent, glycerol as a plasticizer, and sodium carbonate (SC) and/or sodium glycinate (SG) as a CO 2 absorbent. The optical, mechanical, and CO 2 and water vapour absorption properties of SC, SG, and SC/SG films were investigated. Multi-functional films tended to show poor mechanical properties, with a hard texture and an opaque and yellowish colour. The three films had different CO 2 absorption capacities and coefficients, with SC film showing the highest absorption, followed by SC/SG and SG films. The water absorption coefficients were much higher than those of CO 2 , with the opposite dependence on the absorbent compound. The multi-functional benefits of the developed film were shown by using the film for modified atmosphere packaging (MAP) of shiitake mushrooms as an insert label. A tailored MAP design for shiitake mushrooms was produced based on mass transfer mathematical models. The package attached with SC film label was capable of generating the desired internal atmosphere and thus showed the best quality preservation in terms of colour, firmness, flavour score, and bacterial growth after 5-day storage. A tailored MAP system with our multi-functional film can provide an optimal modified atmosphere for CO 2 -sensitive fresh commodities, preserve their quality, and extend their shelf life.

No abstract

In order to estimate the pressure change of modified atmosphere (MA) packaging for powdered infant formula flushed with a mixture of CO 2 and N 2 during distribution and marketing, a mathematical model of the gas state law was established based on the solubility of CO 2 in the product experimentally determined as a function of temperature (463-2,615 mg/kg/atm for 40 to 217C). The developed model was verified using comparisons between measured and estimated values and was used to find the pressure differential across the barrier package wall, which may provide the proper strategy for MA packaging. The MA packages initially flushed with high levels of CO 2 and stored at a low temperature were estimated to result in lower package pressure, which could dictate the desired range of proportion of CO 2 for different combinations of altitude and temperature. Optimum flushing solutions at the product filling stage were found, which accounted for shrinkage, equilibrated mechanical balance or expansion from the pressure difference between the inside and outside of the package under any given geographic conditions. The following results were found: any MA combinations are acceptable at low altitude and low temperature; specific MA compositions consisting of more CO 2 and less N 2 at higher altitude and temperature should be applied at locations of intermediate altitude and moderate temperature; vacuumization is required at high altitude and high temperature. PRACTICAL APPLICATIONSThe developed model of CO 2 absorption and mass balance for MA packaging of powdered infant formula can foresee potential risks of shrinkage or expansion due to the difference between its pressure and ambient pressure under various possible distribution conditions. This model allows the manufacturers to select suitable CO 2 /N 2 proportions at packaging operation under target markets of different altitudes and temperatures.