Work

Gelatin Hydrogel pH Sensors Incorporating Anthocyanins for Intelligent Food Packaging: Towards Enhanced Food Spoilage Detection

Year: 2026

Type: article

Abstract: Protein-based hydrogels composed of gelatin, whey and glycerol were functionalized with red cabbage extract (RCE) to develop natural colorimetric pH sensors for intelligent food packaging. Structural analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed amorphous, hierarchically organized networks where RCE molecules interact with protein chains. The resulting microstructure, consisting of compact surface domains and a porous internal network, may regulate the diffusion of volatile amines into the hydrogel matrix, enabling gradual and stable pH-dependent color transitions. The resulting biocomposite hydrogel exhibited a stable and time-resolved optical response to meat spoilage, correlating structural relaxation with colorimetric sensitivity. Color difference values (ΔE00) calculated based on recorded images indicated strong chromatic changes in the presence of spoilage-related volatiles. Under refrigeration, ΔE00 remained below five, suggesting negligible color shifts. At room temperature, ΔE00 exceeded 20 after 48 h, confirming significant anthocyanin transformation linked to increased alkalinity (pH 7.2–7.5). A positive correlation between ΔE00 and pH was observed, highlighting the hydrogel’s high sensitivity to environmental changes. These findings confirm the potential of RCE-loaded hydrogels as eco-friendly, visual freshness indicators suitable for intelligent packaging applications. The hydrogel films demonstrated a distinct color transition within the pH range of 5.75–7.5, corresponding to the freshness variation interval of chicken meat.

Source: Gels

DOI: 10.3390/gels12040292

Authors: Pompilia Mioara Lopes, Liviu Mare, Lucian Barbu-Tudoran, Alina Gadja, Violeta Popescu

Institutions: Technical University of Cluj-Napoca, Babeș-Bolyai University

Language: English

Topic: Nanocomposite Films for Food Packaging

Subfield: Biomaterials

Field: Materials Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $2,534

Funders: Ministerul Cercetării, Inovării şi Digitalizării, Autoritatea Natională pentru Cercetare Stiintifică, Unitatea Executiva pentru Finantarea Invatamantului Superior, a Cercetarii, Dezvoltarii si Inovarii