Anthocyanin-based biodegradable biosensor film was developed for real-time monitoring of milk spoilage detection. Anthocyanin pigment was extracted from hibiscus petals using 70% ethanol and incorporated into a 5% (w/v) corn starch matrix with glycerol (4–12 mL) as plasticizer via solution casting. The extract exhibited strong pH sensitivity across pH 1–14, showing a colour transition from red (acidic) to greenish-yellow (alkaline). The fabricated film retained similar pH-responsive behaviour with clear, visible colour changes. Phytochemical screening confirmed the presence of flavonoids, phenols, alkaloids, saponins, proteins, and organic acids. During milk spoilage, microbial activity produces lactic acid, lowering pH, which was effectively indicated by the film through rapid colour variation.
Azhar et al. (Wed,) studied this question.