The diffusional properties of polymeric packaging materials are strictly related to the shelf-life of packaged food products and the use and demand of high barrier polymers in food packaging applications are growing in importance. High barrier polymers are generally defined in terms of oxygen and water vapour barrier, considered to be detrimental of the food quality. However, among the components participating in externally-driven degradative reactions, volatile flavours and aroma compounds are neglected. Whereas permeability data and standardised measuring procedures are available for gases and water vapour, information on flavours and other organic compounds are limited. Several studies have been made about the absorption of aroma compounds from citrus juice (G.Pieper et al, 1992; J. Letinsky and G. W. Halek, 1992; G. D. Sadler and R. J. Braddock, 1991), showing a reduction of d-limonene of up to 50% by adsorption into LDPE inside coating packaging (G. Pieper et al., 1992) and many permeations studies have been made too. Permeability’s phenomena can be represented into three steps: first we have a sorption of the molecules on the surface of the film, than the molecules diffuse into the film and finally they can desorbe from the other side of the film. Generally, for a gas permeant, permeability is described as: P=D*S , where “S” is the solubility coefficient and “D” the diffusion coefficient. If this equation can describe appropriately the permeation of permanent gases, on the contrary, if organic vapors are concerned, it does not satisfy, because of: “P” and “S” are temperature-dependent and the value obtained from this equation are good for gases that do not interact between them and that do not produce structural changes into the polymer. As demonstrated by Togawa et al. (X), the d-limonene, generally used as a model permeant, is absorbed into the polyolefin films inducing a swelling and a structural changing, which contribute to the characteristic permeability enhancement of volatile compounds. Aim of this work was to study and evaluate the phenomena of permeability and adsorption of three different aroma compounds in a biaxially oriented polypropylene and in a two biaxially oriented polypropylene-based materials modified, one with TiO2 and the other one expanded. The aroma were tested individually and in a mixture for all the different materials, in order to investigate the interaction’s effect of more than one compounds.
Study of aroma and polymer interactions / Puglisi, Maria Laura; Masino, Francesca; Antonelli, Andrea; Fava, Patrizia. - STAMPA. - (2004), pp. ---.