Retortable food packages

Retortable Food Packages Containing Water-Sensitive Oxygen Barrier... 

Because many food packages must be shelf-stable for many months to years, package testing becomes both expensive and time-consuming. It is necessary to make some estimate of the performance of various candidate structures to assess their barrier potential over the expected shelf life of the product. There have been numerous studies on the retortable food packages (1.-8.) however, a single consistent theory has yet to emerge and experimental details are limited. 

Retortable food packages using EvOH as the oxygen barrier are multilayer structures which are formed by coextrusion. The number of different layers in a the structure can vary a representative five-layer structure is shown in Figure 3. Often one or more layers are added to reuse scrap and regrind in the package. There is a wide range of possible combinations of layer thicknesses which can be used in this type of structure. 

A similar situation does not presently exist for multilayer retortable food packages. In our initial study of LEP and PEP food packages we found that there are very few experimental studies on water permeation in polymers. The studies which we did find were usually limited to low temperature, far removed from retort conditions. The effect of water activity on transport and sorption behavior has not received much attention especially for water-sensitive polymers such as EvOH. In EvOH-type systems the problem is especially acute because EvOH exhibits case II sorption at moderate humidities and its effective glass transition is depressed below storage temperatures at high humidities. Thus, modelling the transport in this type of material is very complex and does not lend itself to analysis with existing models. 

Problem Retortable food packaging is becoming more popular, but shelf-lile, banier properties, and heat resistance are limited. 

Schaper, E. Computer-Aided Barrier Design Yields Retortable Food Package. Proceedings, SPE International Coextrusion Conference 1989 also in Modern Plastics, pp. 94-99, Dec. 

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