UTILIZATION OF CHLORINE DIOXIDE GAS IN FOOD PACKAGING APPLICATIONBySiriyupa NetramaiChlorine dioxide (ClO2) in its gaseous form has been utilized in numerous studies for vapor-phase decontamination, both in treating the produces before packaging, and sanitizing the products inside their packages. Yet, very little is known about its compatibilities with packaging materials, as well as its performances as affected by food packaging system.In this study, mass transfer profiles (permeability, solubility and diffusion coefficients) of ClO2 for 10 types of polymeric packaging materials were determined by an isostatic method using a continuous system for measuring ClO2 concentration with an electrochemical sensor as a detector. The study showed that PET, PLA, BOPP, nylon, and multilayer of EVA/EVOH/EVA have high ClO2 barrier, while PS, LLDPE, LDPE, HDPE, and PVC have low barrier to ClO2. Effects of gaseous ClO2 on physical, mechanical, chemical, and barrier properties of polymeric packaging materials were also studied by exposing selected materials to ClO2 gas. After 14 days of exposure, significant changes, such as increases in barriers to O2 and CO2 of nylon, changes in permselectivity (PCO2/PO2) ratio of up to 46.8% in treated PE, PS, PET, and nylon films, and changes in FT-IR spectra of PET, PLA, and EVA/EVOH/EVA, indicate possible changes in chemical profiles and performance of the materials. Study on influences of packaging design on sanitizing effect of ClO2 gas, on shredded Romaine lettuce, indicated that minimizing the distance between gas releasing spot and target surfaces, as well as, maximizing gas releasing surface could significantly improve antimicrobial activity of ClO2 gas in particular packaging system. Once the interior of the package was optimized, it was observed that the amount of ClO2 gas used per package could be reduced to half of its original dose, and still achieved the same level of log10 CFU reduction of Escherichia coli O157:H7 in packaged shredded lettuce.Once ClO2 is in contact with food products, it will decontaminate the surfaces, as well as being absorbed by the product. The latter amount could not be accounted for its sanitizing capacity. Study on absorption behaviors of Romaine lettuce showed that increasing ClO2 level and/or time of exposure increased residual ClO2 and chlorite (ClO2-) recovered from lettuce sample. The presence of cuts significantly increased the amount of ClO2 consumed, while exceed water did not increased ClO2 absorption by lettuce.The research approach could be of great importance when considering antimicrobial packaging with ClO2 gas as a safety measure. Information generated could also be used to generate parameter for computational modeling of packaging systems.
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