Smart Biopolymer-Based Nanocomposite Materials Containing pH-Sensing Colorimetric Indicators for Food Freshness Monitoring

Abstract

Nanocomposite biopolymer materials containing colorimetric pH-responsive indicators were prepared from gelatin and chitosan nanofibers. Plant-based extracts from barberry and saffron, which both contained anthocyanins, were used as pH indicators. Incorporation of the anthocyanins into the biopolymer films increased their mechanical, water-barrier, and light-screening properties. Infrared spectroscopy and scanning electron microscopy analysis indicated that a uniform biopolymer matrix was formed, with the anthocyanins distributed evenly throughout them. The anthocyanins in the composite films changed color in response to alterations in pH or ammonia gas levels, which was used to monitor changes in the freshness of packaged fish during storage. The anthocyanins also exhibited antioxidant and antimicrobial activity, which meant that they could also be used to slow down the degradation of the fish. Thus, natural anthocyanins could be used as both freshness indicators and preservatives in biopolymer-based nanocomposite packaging materials. These novel materials may therefore be useful alternatives to synthetic plastics for some food packaging applications, thereby improving the environmental friendliness and sustainability of the food supply.

Utilising N‐glutaryl chitosan‐based film with butterfly pea flower anthocyanin as a freshness indicator of chicken breast

“…2 The addition of anthocyanin in films significantly decreased the transparency because of anthocyanin's strong absorption of light waves. 6 The transparency result was supported by the light transmittance test (Figure 5A). A transmittance test was conducted to observe the light barrier properties of films, as UV-Vis light could impact food quality negatively.…”

“…Hence, as potential packaging materials, the film's ability to block the UV and visible light was observed. 6 Ch film exhibited a slightly higher light barrier to UV and visible light, and BPA addition significantly increased the light barrier properties of films. Similar results were observed in previous studies with barberry anthocyanin, which could be due to anthocyanin's properties to absorb UV light.…”

“…Dried film samples were immersed in 20 ml of distilled water with mild shaking for 3 h. Samples were dried at 120 C for 24 h, and the final weight was measured (WS 2 ). Film solubility was calculated by Equation (6).…”

“…4,5 A pH-sensitive colorimetric indicator film was developed to detect the change in pH induced by ammonia, amines and total volatile basic nitrogen (TVBN) from microbial spoilage activities. 2,[6][7][8] Intelligent packaging film indicator comprises synthetic or natural dye and a solid matrix. 4,9 Natural dyes in intelligent packaging, such as anthocyanin, are recently preferred because of their non-toxic properties.…”

Smart packaging for food spoilage assessment based on Hibiscus sabdariffa L. anthocyanin-loaded chitosan films

“…The information provided by these sensors can be used by the food industry, retailers, and consumers to determine when a food should be sold, consumed, and discarded. Colorimetric indicators based on pH changes are one of the most widely explored sensors in food packaging research because of their simplicity and non-invasive nature (Ezati & Rhim, 2020;Tavassoli et al, 2022). Color changes can easily be visually detected by food retailers and consumers (Becerril et al, 2021;Khezerlou et al, 2023).…”