Characterization and pH Response of Passiflora suberosa Extract as a Novel Biosensor Intended for Smart Food Packaging Film

Abstract

Smart food packaging systems encompass a range of innovative technologies that integrate various functionalities to enhance food quality, safety, and consumer convenience. Sensors embedded in smart food packaging materials are commonly synthetic dyes that are known to be toxic and carcinogenic. In this study, biodegradable films were fabricated by employing pH-sensitive anthocyanin extract from Passiflora suberosa, an unexplored source of natural and safer bio-based sensors. Anthocyanin-rich extract of P. suberosa showed remarkable color changes from red (pH 1–3) and eventually turned to pink (pH 4–6), purple (pH 8–10) and green/yellow (pH 11–13) upon contact with different buffer solutions. The films were prepared using a solvent casting process by incorporating different concentrations of P. suberosa anthocyanin (PSA) extracts. Fourier-transform infrared spectroscopy (FT-IR) and Scanning electron microscopy (SEM) analysis were used to study the chemical composition and the surface morphology of the PSA films. The films showed a decreasing trend of moisture content, from 39.5% to 33.2%, upon the addition of increasing concentrations of PSA extracts. The color changes and pH response of the bioactive film were evaluated with a series of standard buffer solutions (pH 3, 5, 7, 9, and 11). The film showed excellent pH-sensitivity properties (visible response within the first 10 s) and good color variations, from red to green, upon testing with the chosen pH buffer. The response surface analysis predicted that maximum color change (ΔE) for the PSA film was 5.38 and could be obtained with the employment of 0.5% of PSA concentration in pH 3 buffer solution. Therefore, incorporating the extract from P. suberosa into the sago starch film matrices equipped the film with excellent pH-responsive characteristics for a new potential formulation of smart food packaging film.