Quantification of Beverage Uptake in Aluminum Beverage Can Lid Liner: Effects of Alcohol Content and Tonic Water on Corrosion Resistance

This study investigates the quantitative relationship between beverage penetration into aluminum can lid interior coatings and the protective effect of increasing alcohol content against corrosion. Electrochemical Impedance Spectroscopy (EIS) was employed, and the coating capacitance (Cco) was specifically monitored to note the changes when the beverages are penetrated into the protective polymer coatings. The Brasher-Kingsbury equation was used to convert capacitance measurements into volume fraction of liquid within the coating. Results demonstrate that higher alcohol content in beverages, exemplified by wine, correlates with enhanced corrosion resistance in aluminum can lids, as evidenced by higher pore resistance (Rpo) and charge transfer resistance (Rct). This protective effect is attributed not only to alcohol and water-mediated oxide stabilization, but also to the presence of resveratrol in wine, a potent antioxidant and metal-chelating agent that further inhibits corrosion. On the other hand, alcoholic lemonade exhibited steadier uptake patterns and energy drinks maintained minimal penetration. In contrast, tonic water exhibited the most aggressive corrosion behavior among the tested beverages, likely due to the synergistic effects of quinine and chloride ions, which compromise the protective oxide layer and accelerate degradation. These findings contribute to a better understanding of beverage-coating interactions, particularly as the market for canned alcoholic beverages continues to expand.