Effect of Silver Nanoparticles on pH-Indicative Color Response and Moisture Content in Intelligent Films Based on Peruvian Purple Potato and Polyvinyl Alcohol

The growing need for sustainable packaging materials with enhanced functionality has prompted our investigation into biodegradable polymers reinforced with nanostructures. In this work, we began by extracting anthocyanins from pigmented native potatoes (Solanum tuberosum) and confirming their concentration via UV–Visible spectroscopy. The corresponding potato starch was then characterized according to its amylose and amylopectin contents. The natural pigments subsequently served as reducing and stabilizing agents in a green synthesis of silver nanoparticles (AgNPs), which were subsequently incorporated into starch matrices derived from the same tuber. To evaluate the performance of the resulting composite films, we examined their pH-responsive color behavior—demonstrating their potential as visual indicators—their molecular structure through FTIR analysis—to verify the successful integration of AgNPs—and their moisture content as a measure of barrier properties. The AgNP-containing films exhibited markedly improved color stability across varying pH levels and superior moisture retention compared to pure starch films. These results illustrate the promise of combining underutilized Andean crops with eco-friendly nanotechnology to produce advanced, biodegradable materials suitable for intelligent food-packaging applications.