DEVELOPMENT OF BIOPOLYMERIC BASED FILMS ENRICHEDWITH BIOACTIVE NATURAL EXTRACT FORFOOD FRESHNESS MONITORING

Abstract

In this work, biopolymeric films of κ-carrageenan (KC)/poly(vinyl alcohol) (PV) were developed by a solution casting method. The optimization of composition between both homopolymers was done at ratios of 40:60, 50:50, and 60:40 κ-carrageenan:poly(vinyl alcohol). The swelling, solubility and moisture resistance of the fabricated films were studied and the results showed that the 40KC/60PV film exhibited outstanding properties. This film showed enhanced tensile strength and elongation at break compared to those of the 50KC/50PV and 60KC/40PV. In order to further improve the physicochemical properties of the film, the organic-inorganic crosslinked films using a siloxane crosslinker were fabricated through a sol-gel process. Investigation on the mechanical properties and swelling ability of the developed hybrid films showed significant improvement in their properties through covalent crosslinking between organic and inorganic networks. Therefore, the crosslinked film was modified for pH-sensitive applications by incorporating various amounts of crude extract obtained from Ruellia squarrosa (Fenzi) Cufod. flowers. The crude extract was rich in various bioactive compounds and capable of color change under different pH conditions. The pH-sensitive films were characterized using ATR-FTIR and SEM-EDX, thermal analysis, mechanical and UV–vis light barrier properties. The intermolecular interaction and compatibility of the crosslinked films incorporated with the crude extract were confirmed by ATR-FTIR and SEM-EDX. Incorporation of the crude extract enabled great improvement in water resistance, thermal stability, UV barrier performance and elongation at break, while a slight decrease in tensile strength at break was revealed. Additionally, the color changes of the pH-sensitive films were observed when exposed to volatile ammonia and immersed in varying pH solutions. The pH-sensitive films showed biodegradability with deteriorated in surface morphology and weight loss over 60 days under the soil burial test. The pH-sensitive films possessed potential use in freshness monitoring application of fresh food tested with shrimp samples at room temperature. The film displayed distinct changes from pale yellow to green along with the spoilage of shrimps. Therefore, incorporation of the crude extract in the hybrid pH-sensitive κ-carrageenan/poly(vinyl alcohol) films exhibit strong potential for application in real-time food freshness monitoring.

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