The present study aims to develop a pH-sensitive biosensor film using natural pigment and to evaluate its effectiveness in detecting milk spoilage in a safe, simple, and reliable manner. A biosensor film based on natural pH indicators was developed using plant-derived pigment. Turmeric powder, containing curcumin, was selected due to its known ability to exhibit visible colour changes in response to variations in pH. The pigments were extracted using different solvents under controlled heating conditions to ensure efficient recovery of bioactive compounds without degradation. The filtered extracts were then combined to enhance the sensitivity and range of colour response. Corn starch-based biopolymer matrix was prepared using distilled water, followed by heating to induce gelatinization and form a uniform viscous solution. To evaluate the performance of the developed film, a series of standard pH solutions ranging from pH 1 to pH 14 were prepared using hydrochloric acid and sodium hydroxide through serial dilution. The biosensor film was exposed to these solutions to analyze its color-changing behaviour across a wide pH range. The results demonstrated clear and distinguishable color variations corresponding to different levels of acidity and basicity, confirming the film’s sensitivity and effectiveness as a pH indicator.
Akhtar et al. (Wed,) studied this question.