Carbon Dioxide Loss of Carbonated Beverages in Pet Packaging: Experimental and Numerical Findings

Abstract

In this study, we investigated the change of carbon dioxide (CO₂) gas in PET bottles over time using experimental and numerical methods, as this is an important quality criterion in carbonated beverage production. Gas loss was modeled using the finite element method (FEM) on 2.5-liter PET bottles, and the effects of temperature, internal pressure, and packaging wall thickness were theoretically evaluated within the framework of the ideal gas equation and Fick's law. Validation was achieved by comparing model results with experimental data, and ideal production conditions were determined. Analyses revealed that gas loss was concentrated primarily in the top and shoulder regions of the bottle, and increasing the thickness in this region reduced diffusion. Furthermore, lowering the filling temperature and increasing internal pressure significantly reduced the transfer of dissolved CO₂ from the packaging to the external environment. Modeling stud-ies were conducted using a three-dimensional design of the bottle geometry, defining boundary conditions to investigate the effects of different material distributions and thick-nesses. Based on the findings, production processes were reorganized, and standardized recipes were created. As a result, the combination of experimental and numerical data has shown that gas losses have been largely controlled, and quality standards can be main-tained for longer periods. This study can provide guidance not only for 2.5-liter PET bot-tles but also for other packaging types. Thus, it was concluded that more planned, higher standard production can be achieved in the carbonated beverage industry, consumer com-plaints can be reduced, and product performance can be maintained sustainably. Under the investigated conditions, reducing storage temperature (291 K to 285 K) decreased the predicted CO₂ loss (12% relative reduction at 180 days), and increasing shoulder thickness (0.25 mm to 0.35 mm) improved barrier performance (4.5% relative improvement at month 6), consistent with production-scale measurements. Model–experiment agreement is reported using quantitative error metrics (RMSE and percentage deviation)