Packaging-food partition coefficients

For a solution /, the apparent partition coefficient between a food 

For a reversible sorption/desorption isotherm for both media, food and polymer, the thermodynamic equilibrium (equal chemical potentials for both media) imposes  

For similar heats of sorption between P and F, the partition coefficients are poorly activated by tenperature. Also note that equation [13.5] takes into account the crystallinity of the polymer, with the apparerrt affinity for food increasing with crystallinity. The expression therefore assumes that the crystalline zones carmot be accessed by diffusing additives. If we disregard the qirantity of additives potentially trapped in the crystalline phases, the previous assumption is due to the diffusion mechanisms of large solutions in the polymer matrices (see section 13.4.2) the relaxation of polymer chains is necessary for the movement of additives and it is negligible in crystalline regions. A secord partition coefficient, denoted by K p/p 

This coefficient can be predicted by molecular modeling using an off-lattice Flory-Huggins simulation approach [GIL 09a, GIL 10, VIT 10], 

The Floiy-Huggins theory generalizes the theory of regular solutions by taking into account the entropic effects associated with the dissimilarity of sizes in the mixing of molecules. The excess chemical potential with regard to the pure bodies is written  

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Estimate the polymer/liquid partition coefficient for cis-3-hexenol between a package with a LDPE material food contact layer. The package contains a food system whose partitioning characteristics can be simulated using 100 % ethanol at 25 °C. Use the UNIFAC activity coefficient estimation method and assume a dilute solution (x, = w, 0.00001). 

Ethanol and aqueous ethanol mixtures play important roles as food simulants for the determination of migration of substances from packaging into foods. Depending on the polarity of the plastic one can use pure ethanol (for nonpolar plastics) or aqueous ethanol mixtures up to 50/50 % (for polar plastics) as alternative simulants to edible oils (see Chapters 9,10 and 11). The estimation of partition coefficients in poly-mer/simulant systems is consequently of practical importance. It is possible to do this for polyolefins in contact with alcohol and aqueous alcohol mixtures with the help of an equation analogous to Eq. (4-100) (Piringer, 1993) ... 

Table 4-9tu Approximate partition coefficient values for various plastic/food package systems.

The consequences of the above results on the partition of aromas and aroma compounds between products and a plastic package can be seen in the values in Table 9-13. It can be seen from the partition coefficients that the values for medium polarity to non-polar substances partitioned between the two wine samples and LDPE are one to two orders of magnitude greater than the partitioning of the same substances between milk and LDPE (limonene, diphenylmethane, diphenyloxide, linalylacetate). The coefficients for the polar substances (cis-3-hexenol, phenyl ethyl alcohol) show comparatively no difference. The K values for non-polar substances partitioned between milk and LDPE are comparable with values obtained for partitioning into 50% ethanol. Despite the relatively low fat content of whole milk (3.5 %), milk behaves quite differently from wine (Kozinowski, 1989). While wine represents a real aqueous solution whose behavior is determined by its water content, milk is not only aqueous but also a fat containing food which, because of its aqueous... 

A guide for estimating the general behavior of partition coefficients is like dissolves like . Thus styrene, a relatively nonpolar hydrocarbon, will tend to remain in a nonpolar polystyrene polymer if the package contains a polar aqueous food (Chapter 9). 

At equilibrium a constant distribution of the migrant between P and F takes place that is independent of its concentration. For relatively small concentrations (< 1 %) this approximate assumption is fulfilled and one defines the partition coefficient A pj as a constant ratio of the migrant concentration in the packaging material, Cp(w/w), to the concentration in the food, Cp(w/w), multiplied by the density ratio ... 

For Dp Dp and /fpp < 1 we obtain eqn 8.24. If the diffusion coefficients in the packaging and in the food are approximately equal, the partition coefficient, /fpp determines transport through the system. The packaging determines the rate of the whole process. If the migrant dissolves much better in the food than in the packaging, that means /fpp < 1 and the food determines the rate of the whole process. But if the migrant dissolves much better in the packaging than in the food, A pp 1. If Dp < Dp the mass transport is determined by the diffusion coefficient in the food. Dp and the partition coefficient, A"pp. This leads to the build up of a concentration profile in the foodstuff. An exact analytical solution of the differential equation that takes into consideration the diffusion in food and finite values for Vp and Vp is not available and in consequence the application of numerical methods is necessary. 

BANER, A. L., 2000, Partition coefficients, in Piringer, O.-G. and Baner, A. L., Plastic Packaging Materials for Food, Wiley-VCH, Weinheim, New York. 

Triantafyllou et al. (2005), in studies on transfer of potential contaminants from paper and board to food, measured partition coefficients between packaging and air for a range of substances. This was, therefore, an attempt to measure the potential for gas-phase transfer. A mixture of acetophenone (b.p. 203 °C), naphthalene (b.p. 218 °C), benzophenone (b.p. 306 °C), dibutyl phthalate (b.p. 340 °C) and methyl stearate (b.p. 443 °C) was placed in a vial together with samples of test liner made from virgin fibres or triplex board made from 100% recycled fibre. There was no contact between the substances and the paper or board. Vials were sealed and heated at 70 °C or 100 °C and then the paper removed and analysed for uptake of substances. Conclusions from the studies were that ... 

When the volume of the environmental fluid is finite, diffusion of a minor chemical species will proceed until equilibrium is attained. At equilibrium the diffusing species will partition itself between the polymer and environmental fluid phases defined by a partition coefficient K. The estimation of K is an importnat consideration in drug release from polymeric delivery devices (1 ) and in applications of polymers as food packaging materials (2 ). 

The ultimate extent of migration of a particular substance from a package to a product depends on the initial amount of the migrating substance in the plastic, and on the partition coefficient between the plastic and the food. The partition coefficient determines the equilibrium distribution of the compound in closed systems. The actual amount of migration occurring in a given time depends on those factors, as well as on the rate of transfer. 

The contamination of food by substances in packaging involves diffusion into the packaging material, controlled by a diffusion coefficient D (units SI m -s ), and the distribution of substances between the packaging and food, controlled by a partition coefficient Kp/p, as well as the sampling of substances from the food side as shown in Figure 13.5. The first two properties are explained in detail in sections 13.4.1 and section 13.4.2, respectively. 

This section covers the relations between the chemical structure of the migrants and the main properties controlling the migration of these substances through polymers partition coefficients and diffusion coefficients. For brevity, only the food-packaging partition coefficients are presented, but the same principles can be apphed to polymer 1/polymer 2 partition coefficients. We can refer to data and additional models in [VIT 09]. 

Arab Tehrany, E., Desobry, S. 2004. Partition coefficient in food/packaging systems. Food Additives and Contaminants, 21(12) 1186-1202. 

Kurek, M. Moundanga, S. Favier, C. GaUc, K. Debeaufort, F. Antimicrobial efficiency of carvacrol vapour related to mass partition coefficient when incorporated in chitosan based films aimed for active packaging. Food Control, 2013,32(1), 168-175. 

A.L. Baner, in Partition Coefficients (O. Piringer and A. Baner, eds.), pp. 79-123, Plastic Packaging Materials for Food, Vol. 1, Wiley-VCH Verlag GmbH, Weinheim, Germany, 2000. 

The partition coefficient for a pollutant between the package and the food ... 

The amount of packaging components that may be leached by food or food simulating solvents depends on the original concentration of the particular component or migrant in the polymer, its solubility in the solvent and/or the partition coefficient between the polymer and solvent as well as temperature and time [4]. 

Kpp is the partition coefficient of migrant between food and packaging film, where... 

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