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Chen, Xi,Lee, Dong Sun,Zhu, Xuntao,Yam, Kit L. American Chemical Society 2012 Journal of agricultural and food chemistry Vol.60 No.13
<P>This paper investigated the feasibility of manipulatingpackagingpolymers with various degrees of hydrophobicity to release two antioxidants,tocopherol and quercetin, at rates suitable for long-term inhibitionof lipid oxidation in food. For example, one antioxidant can be releasedat a fast rate to provide short-term/intermediate protection, whereasthe other antioxidant can be released at a slower rate to provideintermediate/long-term protection of lipid oxidation. Controlled-releasepackaging films containing tocopherol and quercetin were producedusing ethylene vinyl alcohol (EVOH), ethylene vinyl acetate (EVA),low-density polyethylene (LDPE), and polypropylene (PP) polymers;the release of these antioxidants to 95% ethanol (a fatty food simulant)was measured using UV–vis spectrophotometry, and Fickian diffusionmodels with appropriate initial and boundary conditions were usedto fit the data. For films containing only quercetin, the resultsshow that the release of quercetin was much faster but lasted fora much shorter time for hydrophilic polymers (EVOH and EVA) than forhydrophobic polymers (LDPE and PP). For binary antioxidant films containingtocopherol and quercetin, the results show that tocopherol releasedmore rapidly but for a shorter period of time than quercetin in LDPEand EVOH films, and the difference is more pronounced for LDPE filmsthan EVOH films. The results also show the presence of tocopherolcan accelerate the release of quercetin. Although none of the filmsproduced is acceptable for long-term lipid oxidation inhibition, thestudy provides encouraging results suggesting that acceptable filmsmay be produced in the future using polymer blend films.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2012/jafcau.2012.60.issue-13/jf2045813/production/images/medium/jf-2011-045813_0006.gif'></P>
Model for Estimating CO2 Concentration in Package Headspace of Microbiologically Perishable Food
Dong Sun Lee,Hwan Ki Kim,Duck Soon An,Kit L. Yam 한국식품영양과학회 2011 Preventive Nutrition and Food Science Vol.16 No.4
Levels of carbon dioxide gas, a metabolite of microbial growth, have been reported to parallel the onset of microbial spoilage and may be used as a convenient index for a packaged food’s shelf life. This study aimed to establish a kinetic model of CO₂ production from perishable food for the potential use for shelf life control in the food supply chain. Aerobic bacterial count and package CO₂ concentration were measured during the storage of seasoned pork meat at four temperatures (0, 5, 10 and 15℃), and their interrelationship was investigated to establish a mathematical model. The microbial growth at constant temperature was described by using model of Baranyi and Roberts. CO₂ production from the stored food could be explained by taking care of its yield and maintenance factors linked to the microbial growth. By establishing the temperature dependence of the microbial growth and CO₂ yield factor, CO₂ partial pressure or concentration in package headspace could be estimated to a limited extent, which is helpful for controlling the shelf life under constant and dynamic temperature conditions. Application and efficacy of the model needs to be improved with further refinement in the model.
Lee, Dong-Sun,Kim, Hwan-Ki,An, Duck-Soon,Yam, Kit L. The Korean Society of Food Science and Nutrition 2011 Preventive Nutrition and Food Science Vol.16 No.4
Levels of carbon dioxide gas, a metabolite of microbial growth, have been reported to parallel the onset of microbial spoilage and may be used as a convenient index for a packaged food's shelf life. This study aimed to establish a kinetic model of $CO_2$ production from perishable food for the potential use for shelf life control in the food supply chain. Aerobic bacterial count and package $CO_2$ concentration were measured during the storage of seasoned pork meat at four temperatures (0, 5, 10 and $15^{\circ}C$), and their interrelationship was investigated to establish a mathematical model. The microbial growth at constant temperature was described by using model of Baranyi and Roberts. $CO_2$ production from the stored food could be explained by taking care of its yield and maintenance factors linked to the microbial growth. By establishing the temperature dependence of the microbial growth and $CO_2$ yield factor, $CO_2$ partial pressure or concentration in package headspace could be estimated to a limited extent, which is helpful for controlling the shelf life under constant and dynamic temperature conditions. Application and efficacy of the model needs to be improved with further refinement in the model.