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  • 11
    Electronic Resource
    Electronic Resource
    SORPTION OF VINYLCHLORIDE ONTO POLYVINYLCHLORIDE BY CLASSICAL PARTITION AND INVERSE GAS CHROMATOGRAPHY: COMPARISON OF TWO METHODS (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food processing and preservation 9 (1985), S. 0 
    Details
    ISSN: 1745-4549
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sorption of vinylchloride onto Polyvinylchloride was studied using both classical partition and inverse gas chromatography. The effect of temperature, polymer particle size and monomer concentration were particularly examined. Data from both methods showed that at very low concentrations, the monomer was strongly retained by the polymer with equilibrium distribution in favor of the polymer increasing as concentration decreased. Increase in temperature resulted in increase of the kinetic energy of VCM molecules hence desorption was thermo-dynamically more favored than at lower temperatures. Decrease in polymer particle size resulted in a greater binding of the monomer by the polymer, due to uncovering of additional active sites in the polymer. Values for the thermodynamic parameters calculated using the two methods were in fair agreement. Results were in accordance with the active site hypothesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4549.1985.tb00722.x
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  • 12
    Electronic Resource
    Electronic Resource
    THE INTERACTION BETWEEN ACRYLONITRILE AND ACRYLONITRILE – STYRENE COPOLYMER BY INVERSE GAS CHROMATOGRAPHY (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food processing and preservation 5 (1981), S. 0 
    Details
    ISSN: 1745-4549
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: The interaction between acrylonitrile and an acrylonitrile-styrene copolymer was studied by the use of Inverse Gas Chromatography (IGC). The Gibb's free energy, the ethalpy and entropy were calculated from the chromatographic data. It was found that the negative value of the free energy increases with the decrease in temperature and that the negative value of the heat of adsorption increases with the decrease in the amount of ACN injected into the gas chromatograph. These results indicate that the polymer-monomer interaction increases with the decrease in temperature and monomer concentration pointing to the possibility that at very low monomer concentrations no migration may occur, at ambient temperatures, from a package made of the studied polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4549.1981.tb00633.x
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  • 13
    Electronic Resource
    Electronic Resource
    TRANSPORT CONSIDERATIONS OF POTENTIAL MIGRANTS FROM FOOD PACKAGING MATERIALS (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food processing and preservation 4 (1980), S. 0 
    Details
    ISSN: 1745-4549
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Migration from polymeric packaging materials to containd foods is essentially a desorption process involving low molecular weight species in a polymeric matrix. Such desorption can affect both intrinsic quality and safety of ingested packaged food. A legalistic problem also exists because of present regulations of “zero tolerance” where a possible migrant is a potential carcinogen. The precise elucidation of desorption, at extremely low levels of initial migrant concentration, has thus become a major issue. However, desorption at such levels has not been adequately studied.Sorption/desorption studies conducted with food simulating solvents and foods in classical phase distribution systems shows marked concentration dependence for certain poly (vinyl chloride) resins. The thermodynamic relations between selected monomer/polymer systems have been further studied by inverse phase gas chromatography for both poly (vinyl chloride) and poly (acrylonitrile) and some of its copolymers. Results from these studies suggest that entropic relations are dominant at such low levels for transport.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-4549.1980.tb00594.x
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  • 14
    Electronic Resource
    Electronic Resource
    Isolation and Identification of Volatile Compounds from Glassine Packages (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 54 (1989), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The volatile flavor compounds in glassine packages were characterized using headspace concentration technique and GC/MS. The major compounds identified were 2,2-dimethyl-1,3-propanediol, 3,3-di-methyl-4-hydroxybutanal, and 2,2-dimethyl-1,3-propanediol diacetate. Compounds representing hydrocarbons, alcohols, and phthalates were also identified. The majority of these compounds could be attributed to residues from the lacquer applied to the glassine paper as a curable coating.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1989.tb04707.x
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  • 15
    Electronic Resource
    Electronic Resource
    Water Sorption Isotherms of Sucrose and Glucose by Inverse Gas Chromatography (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 46 (1981), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A novel gas chromatographic procedure was used to obtain the water sorption isotherms of sucrose and glucose. The method allows calculation of partial pressure of water and water uptake directly from a chromatogram. The isotherms developed are in a water activity range well below that of conventionally developed isotherms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1981.tb02989.x
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  • 16
    Electronic Resource
    Electronic Resource
    APPLICATION OF INVERSE PHASE GAS CHROMATOGRAPHY FOR DETERMINATION OF BOUND WATER IN COLLAGEN (1979)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 44 (1979), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inverse phase gas chromatography was applied to the study of water sorption by proteins and was shown to be suitable for the investigation of sorption processes at moisture contents as low as 0.1% (wt/wt)-a region of the isotherm, unexplored thus far. The sorption isotherm of calf-hide collagen was determined at 55°C. The present publication provides details of this new procedure. A subsequent paper will deal with the thermodynamics of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1979.tb03469.x
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  • 17
    Electronic Resource
    Electronic Resource
    Odor Barrier Properties of Multi-Layer Packaging Films at Different Relative Humidities (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 52 (1987), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A permeation cell method was developed for the determination of transmission rates of organic vapors through flexible packaging materials. The permeation rates at 23°C of some compounds for several composite films at 0% and 75% relative humidity (RH) indicated that the polyethylene vinyl alcohol and nylon combinations exhibited superior barrier properties even at elevated RH, provided that moisture barrier films were present in the laminate construction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1987.tb06641.x
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  • 18
    Electronic Resource
    Electronic Resource
    Moisture Sorption of Dry Bakery Products by Inverse Gas Chromatography (1985)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 50 (1985), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Inverse gas chromatography was used to study moisture sorption properties of two bakery products as a function of temperature and food structure. Crackers (high in fat, low in sugar) were found to be more hygroscopic than sweet biscuits. Sorption isotherms at different temperatures were determined to obtain thermodynamic parameters of sorption. Enthalpy and entropy functions as weU as Zimm-Lundberg clustering analysis suggested different sorption mechanisms in the two systems. Active site binding mechanism was manifested in the cracker system by highly negative enthalpy and entropy changes at low moisture contents. Water-water interactions were more favored in the sweet biscuit system at the same free energy level. Addition of crystalline sucrose decreased hygroscopicity of the cracker system and increased formation of water-water interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1985.tb13426.x
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  • 19
    Electronic Resource
    Electronic Resource
    Sorption/Desorption of VCM in PVC Selected Food Simulants Systems (1982)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 47 (1982), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Sorption/desorption studies of VCM in the systems PVC/VCM/water, PVC/VCM/corn oil an PVC/VCM/heptane were carried out. At low VCM concentrations, classical curves are obtained, where the sorption isotherms are located below their desorption counterparts. Above a certain VCM concentration a crossover exists and an inversion of the curves occurs. It was suggested that the intersection between the curves represents the point where all the active sites in the polymeric matrix are occupied by monomer molecules. The negative values of the total Gibb's free energy and the energy of mixing in the polymer were found to increase with the decrease in monomer concentration pointing out to the possibility that at low enough monomer concentrations no migration of VCM into the contained food from a PVC package may occur.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1982.tb07649.x
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  • 20
    Electronic Resource
    Electronic Resource
    MIGRATION OF INDIRECT, FOOD ADDITIVES: A PHYSICAL CHEMICAL APPROACH (1980)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of food science 45 (1980), S. 0 
    Details
    ISSN: 1750-3841
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Active site binding of vinyl chloride monomer by polyvinyl chloride has been demonstrated in 2 of 3 unplasticized resins, by equilibrium partitioning studies. The magnitude of this effect was less than what was observed in previous studies. The potential for active site binding to be a limiting, factor for the migration of indirect food additives may thus depend upon chemical and morphological features of the particular resin used to manufacture the food contact article. Inverse phase gas-solid chromatographic studies have also shown active site binding in the unplasticized resin sample studied by this method. Simple dissolution was shown to be the predominant mode of monomer/polymer interaction, for the plasticized counterpart of this resin. These studies have shown the potential for obtaining reliable data for interaction of polymer resins with indirect food additive type molecules by this more quickly performed technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2621.1980.tb07499.x
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