From: Food Packages

From glass to plastic

Plastic can be used as a substitute for glass without influencing shelf life negatively. Results obtained by experiments carried out on cuccìa and on prepared tomato sauce, confirm this theory. It’s not difficult to understand the reasons of the success of packaging made from plastic materials. Practicality, given by new light and unbreakable materials, has contributed to the growth of innovative packaging forms. As time went by, handling and transport cost reduction progressed along with the evolution of form techniques, which made it possible to obtain forms and shapes more suited to the kind of product. Besides, lightening process of plastic packaging means savings for producers and is a key point of environmental policy. The proposal of a new packaging may not be exclusively justified by economical, practical and marketing reasons. Introduction of an innovation can’t be apart from a meticulous study of the effects of the new material on kinetics of decay of the product. In this study we report the results of 2 recent experiments on two foods usually marketed in glass: cuccìa and tomato sauce.

Cuccia in PET
Cuccia is a typical Sicilian dish based on boiled wheat grains inclusive of aleuronic layer and of embryo. Afterwards cooked wheat is flavoured with salt and vinegar and it is packaged in glass containers where oil is the prevailing liquid.
Influence of different typologies of containers (glass, PET and PET charged with oxygen scavenger) on kinetics of decay of chemical and sensory quality has been considered.
Cuccìa quality has been described by means of sensory, chemical and mechanical characteristics. Results showed that PET containers could slow down kinetics of decay of cuccìa in the same way as glass containers.
Because of low oxygen concentration of active PET, this kind of packaging, if compared with all PET made containers, hasn’t brought about differences in the kinetics of decay of quality of the above mentioned product.

Tomato sauce in polymerical materials
Lately the market tends to the marketing of sauces in semi preservation, which are usually packed in polymerical containers and which have a shelf life limited to 45-60 days in refrigerating condition. The main cause of degradation is microbiological, but also chemical and nutritional modifications must be taken into consideration. The oxidation of lipidic fraction and pigment photodegradation (ex: carotenoid in tomato sauces) is among the most relevant modification and is responsible for colour variation and for the loss of nutritional quality.
The proposed experimental test compared the effect of different packaging materials (PP, PET, PET with oxygen scavengers) on kinetics of decay of sauces in semi preservation. Extending conservation beyond shelf life, generally attributed to sauces in semi preservation, the considered quality indexes haven’t undergone any relevant changes and containers used for tests can efficaciously be considered one as a substitute for the other, as packaging materials don’t affect most of the considered indexes of quality. With the exception of contained in lycopene (whose decrease was quicker in PET and PP than in glass and PET + oxygen scavenger) and peroxide number (which reached higher values in PET).