Improvement of CO2 retention of PET bottles for carbonated soft drinks

One of the major aims pursued by the carbonated soft drinks industry is to extend the shelf-life of PET-packaged products, in order to guarantee the consumers with the original characteristics and quality. Most of the responsibility in the shelf-life extension of such products has to be attributed to the bottle material performances, such as the barrier properties to gases with special regards for the ability to maintain the internal CO2 through the shelf-life. Tests on carbonated soft drinks bottles are performed at every change (design, volume, etc.) of the package, in order to verify the performances of the new bottle with special regards for the CO2 retention properties. The research aims at the evaluation of new bottles addressed to the packaging of a sugar free and a caffeine free carbonated soft drink (Coca-Cola Light e Coca-Cola Caffeine Free), recently launched on the Italian market. The start of commercialisation for these new products is the result of a project named "Silver and Gold", which takes the name from the new colours of the new bottles. Such bottles are produced using the same PET resin as the standard ones, with the only exception of master batch dyes used in the test materials. The CO2 retention performances of Silver and Gold bottles were investigated in comparison with the standard bottle used as a control. Results showed that CO2 retention was improved in the Silver and Gold bottles, which retained averagely 88% of the initial CO2 level after 14 weeks of storage, approximately 10% more than the standard bottles.