Utilization of chlorine dioxide gas in food packaging application
Siriyupa Netramai, Maria Rubino, Rafael A. Auras, Laura Bix and Harold Hughes
Thesis, Doctor of Philosophy (Food Science), Michigan State University. 263 pages. 2010.
2010
บทคัดย่อ
Chlorine dioxide (ClO2) in its gaseous form has been used in numerous studies for vapor-phase decontamination, both in treating produce before packaging, and decontaminating the products inside their packages. Yet, very little is known about its compatibilities with packaging materials or its performance as affected by food packaging systems. The overall goal of this dissertation was to evaluate potential use of ClO2 gas as an antimicrobial agent for food packaging applications.
In the first 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. Overall, PET, PLA, BOPP, nylon, and multilayer of EVA/EVOH/EVA had high ClO2 barrier, while PS, LLDPE, LDPE, HDPE, and PVC provided low barrier to ClO2. Effects of gaseous ClO2 on physical, mechanical, chemical, and barrier properties of polymeric packaging materials were then 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 antimicrobial effect of ClO2 gas, on shredded Romaine lettuce, indicated that minimizing the distance between gas releasing location and target surfaces, as well as, maximizing the area of gas release 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 used per package could be reduced to half of its original concentration (from 8 to 4 mgClO2 /kg lettuce per day), while still achieving the same level of log10 CFU reduction of Escherichia coli O157:H7 in packaged shredded lettuce.
When in contact with food, ClO2 gas will decontaminate the surfaces, as well as being absorbed by the product. The latter amount could not be accounted for its antimicrobial capacity. Study on absorption behavior of Romaine lettuce showed that increasing ClO2 level and/or time of exposure increased residual ClO2 and chlorite (ClO2- ) recovered from Romaine lettuce sample. The presence of cuts significantly increased the amount of ClO2 consumed, while exceed water did not increase ClO2 absorption by lettuce.
This 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 parameters for computational modeling of packaging systems.