Polyvinyl alcohol-based films plasticized with an edible sweetened gel enriched with antioxidant carminic acid

Abstract

Edible sweetened gels are commonly used in bakery products. The aim of this work is to show that certain edible gels can be used as functional modifiers for biodegradable polymers. These gels are rich in glucose and sugars, containing much less water. To date, sugars (glucose, maltose, sucrose, and d -allulose), have also been used as natural plasticizers for polysaccharides to form edible films. In this work, we prepared an edible gel based on glucose, sugar and carrageenan as a gelling agent and tested the gel's plasticizing effect on polyvinyl alcohol, PVA. Carminic acid, a natural pigment and a powerful antioxidant with antiradical activity, was added to the gels. The optimum plasticizing effect was obtained from 1:1 gel: polymer mixing ratio with 28.6 wt% total sugars. Carminic acid also assisted with low oxygen permeation (OP, 3.4 cm 3 μm/m 2 .day.atm) values due to its oxidative radical scavenging chemistry. In aqueous and ethanoic solutions, the films released carminic acid in a sustained manner and within 36 h, strong inhibition was measured against standard stable free-radical molecules known as DPPH and ABTS +• . Finally, the films demonstrated effective color change upon exposure to ammonia vapors that can be exploited towards food spoilage detection. These materials could be effectively used as freestanding, protective antioxidant barrier films or can be laminated with other hydrophobic thermoplastics for general packaging applications. • A sugar based carrageenan gel was used as plasticizer for PVA. • The gel contained carminic acid, which acted as a strong antioxidant. • The plasticized films had very low oxygen permeation values. • The films changed color upon exposure to ammonia vapors. • The plasticized films could be used for multilayer packaging.