Monitoring freshness of chicken using intelligent pH indicator packaging film composed of polyvinyl alcohol/guar gum integrated with Ipomoea coccinea extract

Abstract

With enormous amounts of food being wasted at every level of consumption, the future of food security is in jeopardy. The confusion aroused due to “best before” or “use by” can be eliminated by intelligent colorimetric indicators which communicate the quality of food. pH indicators have gained their attention because they are simple and visually informative. Using natural pigments to fabricate pH indicators can help reducing use of carcinogenic chemicals in packaging. In this work, anthocyanins extracted from a novel flower source named Ipomoea coccinea (ICE) were added to polyvinyl alcohol (PVA) and guar gum (GG) matrix in varying amounts and was applied as antioxidant and intelligent pH indicator film to monitor the freshness of chicken fillets and to visually communicate the quality of chicken. The pH indicator was characterized for halochromism, antioxidant activity, thermogravimetry, water solubility, water contact angle, surface morphology, colorimetry and X-ray diffractograms. The color change of the extract was observed from orange to red to yellow. Film with highest amount of anthocyanin extract has increased thickness of 150.5 ± 17.86a (μm), decreased water vapor transmission rate of 4.95 ± 0.29a (mg day−1 cm−2) and has a crystallinity of 52.35%. Anthocyanins started to degrade at 65 °C according to thermogravimetric analysis. The film with 20% ICE showed an excellent color change in pH solutions and the highest antioxidant activity of ∼91%. The food study results suggested that the developed film has the potential to be employed as an active and intelligent visual indicator in poultry packaging.