PLA membranes as functional alternatives to PVC in potentiometric pH electrodes for wine and beverages.

The replacement of conventional polymers with safer and more sustainable materials is an urgent challenge in sensor development, particularly for applications in food analysis. Beyond sustainability, new materials must also ensure food compatibility, reduce plastic waste, and provide reliable analytical performance. In this context, polylactic acid (PLA) was evaluated as a polymeric matrix for potentiometric pH electrodes and compared with traditional PVC membranes and a commercial glass electrode. PLA and PVC membranes were prepared by solvent casting, conditioned, and subsequently tested in representative agro-food matrices such as wines, juices, soft drinks, and vinegars. Sensitivity, linearity, accuracy, matrix effects, reproducibility, repeatability, electrical resistance and lifetime were systematically assessed

PLA membranes exhibited lower sensitivity (-19 ± 2 mV/pH) than PVC (-52 ± 3 mV/pH); however, they achieved comparable accuracy to the reference system, with a global bias of -0.094 ± 0.089 pH across all matrices. The reduced slope of PLA minimized matrix interferences, especially under acidic conditions and in the presence of ethanol. The membranes exhibited low electrical resistance, good repeatability and reproducibility, and an operational lifetime of approximately 15 days even under aggressive storage conditions.

Overall, PLA demonstrated its potential as a food-compatible and biodegradable alternative to PVC in potentiometric sensors. By combining accuracy comparable to glass electrodes with enhanced resistance to matrix effects and the additional benefit of reduced plastic waste, PLA emerges as a strong candidate for next-generation enological sensors, with promising prospects for integration into additive manufacturing technologies without the need for solvent processing.