Edible barrier properties

An edible film should have good water vapor barrier properties (low or no water permeation and diffusion through film), which should not increase or increase very little with increasing relative vapor pressure (Lawton, 1996). Films should withstand mechanical stress and strain to such an extent that they do not break easily under a decent mechanical force (Talja et al, 2008). Thus, composition of starch-based films is an important factor influencing its barrier and mechanical properties. Also, starch-based edible films may have an impact on the sensory and textural characteristics of the food. 

Cardboard baking dishes coated with crystalline PET or crystalline PBT can be used in convection ovens up to temperatures of 200-220 °C. Single portion dishes made from heat formed films find wide applications in microwave ovens. Biaxially stretched PET covers an important application area of bottles, wide mouth jars and cans. These containers are particularly well suited for carbonated beverages, edible oils and spirits. The gas barrier properties can be improved by coextrusion with a barrier layer such as polyamide. With improved barrier properties it can also be used for beer and wine. 

Several studies reviewed formulations, barrier properties and possible application of edible protein-based films (Table 23.3) (Gennadios et al. 1994 Krochta and Me Hugh 1997 Torres 1994). Overall, similarly to polysaccharide films, proteins exhibit relatively low moisture barrier properties, two to four times lower than conventional polymeric packaging materials (McHugh and Krochta 1994d). The limited resistance of protein films to water vapour transmission is attributed to their substantial hydro-philicity and to the amounts of plasticizers, such as glycerol and sorbitol, incorpo-... 

Debeaufort, F., and Voilley, A. (1995). Effect of surfactants and drying rate on barrier properties of emulsified edible films. Int. J. Food Sci. Technol. 30(2), 183-190. 

Gennadios, A., Weller, C.L., and Testing, R.F. (1993). Modification of physical and barrier properties of edible wheat gluten-based films. Cereal Chem., 70 426-429. 

Greener, I.K., and Fennema, O. (1989a). Barrier properties and surfaee charaeteristics of edible, bilayer films. J. FoodSci. 54(6), 1393-1399. 

Guillard, V., Guillbert, S., Bonazzi, C., and Gontard, N. (2004a). Edible acetylated monoglyceride films Effect of film-forming technique on moisture barrier properties. J. American OilChem. Soc. 81, 1053-1058. 

Koelsch, C. (1994). Edible water vapor barriers properties and promises. Trends Food Sci. Technol. 5, 76-81. 

Koelsch, C.M., and Labuza, T.P. (1992). Functional physical and morphological properties of methyl cellulose and fatty acids-based edible barriers. Lebensmittel Wissenschqft and Technologic. 25,401-411. 

Park, H.J., and Chinnan, M.S. (1995). Gas and water vapor barrier properties of edible films from protein and cellulosic materials. J. Food Eng. 25,497-507. 

Miller, K.S. and Krochta, J.M. Oxygen and aroma barrier properties of edible films a review. Trends Food Sci. TechnoL, 8, 228, 1997. 

Among the films invesfigafed, edible films based on proteins showed the best mechanical properties. However, their barrier properties are variable (Kester and Fennema, 1986). The increase of cohesion between protein pol) eptide chains was thought to be effective toward the improvement of the barrier properties of fhe films. For insfance, fhe presence of calcium was reported to decrease the water permeability of caseinate-based film (Avena-Bustillos and Krochta, 1993). 

Fabra, M.J., Hambleton, A., Talens, R, Debeaufort, R, Chiralt, A., Voilley, A. 2008. Aroma barrier properties of sodium caseinate-based edible films. Biomacromolecules, 9(5) 9, 1406-1410. 

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