Development and characterization of copper nanocomposite containing bilayer film for coconut oil packaging

Copper nanocomposite containing edible bilayer pouch was fabricated from a heat sealable casein protein layer laminated with sodium alginate–pectin, and the developed pouch was used to package the coconut edible oil. The copper nanocomposite was synthesized by using heat treated and NaBH₄ treated methods. The synthesized nanocomposites were incorporated in the bilayer film. Effect of incorporation of copper nanocomposite on mechanical, barrier, and antimicrobial properties of the film was then investigated. Addition of nanocomposite improved the tensile strength (TS), light barrier properties but reduced the % elongation at break. Thermal stability of the bilayer was improved after the addition of nanocomposite. Antimicrobial property of heat treated nanocomposite containing film (zone of inhibition 11 mm) was higher than to the film containing NaBH₄‐treated nanoparticles (inhibition zone 4 mm) against the growth of Escherichia coli. Lower WVTR and less transparency of the film made it suitable to reduce the rate of oxidation of coconut oil during storage. Rate of increase in oxidation of coconut oil was significantly less (i.e., 14 meqiv. kg⁻¹ after 90 days of storage) when stored in nanocomposite containing edible pouches. PRACTICAL APPLICATIONS: Usages of plastic packaging material have a number of drawbacks like generation of waste associated with the materials used to package foods; tearing of the package for the use of the oil is little bit difficult for the consumer and left over after use may get waste. Edible packaging prepared from natural sources may be an effective alternative to avoid the problem of disposing of packaging material. Single‐layer edible packaging is not so acceptable for commercial packaging due to poor barrier properties, and therefore, in the present investigation, lamination of pectin–sodium alginate and casein was used for the fabrication of bilayer edible pouches. Synthesized copper nanocomposite was incorporated in pectin layer to improve the antimicrobial properties of the film. In present investigation, the developed pouch was used to package the edible coconut oil and the oxidative stability of oil during storage was also studied.