Preparation of bioactive functional poly(lactic acid)/curcumin composite film for food packaging application Swarup Roy, Jong-Whan Rhim ⁎ Department of Food and Nutrition, BioNanocomposite Research Institute, Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, Republic of Korea abstract article info Article history: Received 23 June 2020 Received in revised form 7 August 2020 Accepted 10 August 2020 Available online 16 August 2020 Keywords: PLA Curcumin Composite film Transparency Antioxidant activity Packaging Poly (lactic acid)-based functional films incorporated with curcumin have been prepared using a solution casting method. The PLA/curcumin composite film was flexible and highly transparent with bright yellow color. Curcumin was uniformly dispersed in the PLA matrix and showed excellent compatibility with PLA, as evidenced by the FE-SEM, DSC and FTIR test results. The addition of curcumin increased the mechanical properties slightly without changing the thermal stability of the PLA film. The composite film also exhibits excellent UV-barrier properties without much-sacrificing transparency of the PLA film. The water vapor permeability (WVP) and water contact angle (WCA) of the PLA film were slightly increased by the addition of curcumin but were not sta- tistically significant (p > .05). The PLA/curcumin composite film also showed excellent antioxidant and some an- tibacterial activity. The functional PLA/curcumin composite films with improved physical and functional properties can be used in active food packaging applications. © 2020 Elsevier B.V. All rights reserved. 1. Introduction Plastic is very versatile materials having excellent physical properties with lightweight, good processability and economy and is widely used in various fields such as food packaging, commodity products, medical de- vices, and construction. Plastic production has been increasing exponen- tially with an annual growth rate of 8.7% since the beginning of large scale production in early 1950. The global annual production of plastic materials currently exceeds 335 million tonnes, more than 40% of which is used for the production of single-use packaging [1,2]. Since most plas- tics are non-biodegradable, disposal of plastic materials after use without recycling will cause serious environmental problems [3]. Concerns on the environmental problems and exhaust of petrochemical resources caused by the non-biodegradable plastics stimulated to produce eco-friendly re- newable, biodegradable biopolymeric materials [4–6]. As a result, renew- able resource-based biodegradable and bioplastic packaging materials received considerable interest in replacing non-biodegradable polymers [7]. Renewable resource-based bioplastics suitable for such purpose in- clude microbial polyesters such as polyhydroxyalkanoates (PHAs), e.g., polyhydroxybutyrate (PHB), polyhydroxyvalerate (PHV), and their copolymers, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), and chemically synthesized polymers such as poly (glycolic acid) (PGA), poly (ε-caprolactone) (PCL), poly (vinyl alcohol) (PVOH), and poly (lactide) (PLA) [8]. Among them, PLA is considered a promising material due to its bio- degradability, biocompatibility, high transparency, good mechanical properties, moderate water resistance, and commercial availability at a reasonable price [9,10]. PLA is synthesized from lactic acid, which is produced using environmentally sustainable sources such as corn or sugar beets microorganisms [11]. PLA is used for food contact surfaces and is generally recognized as safe. However, low thermal stability, rel- atively low gas barrier (O 2 and water vapor) properties, and brittleness limit the use of PLA in food packaging applications [9,12,13]. Methods of mixing functional filler materials are often used to improve the physical and functional properties of PLA films [14]. Various functional filler ma- terials such as nanoclay, nanocellulose, metallic nanoparticles (Ag, ZnO, TiO 2, etc.), and natural bioactive substances (essential oil, grapefruit seed extract, limonene, etc.), have been used to improve physicochem- ical and biological properties of PLA films [15–27]. As one of such func- tional materials, curcumin is interesting due to its functional properties (antioxidant and antimicrobial activity) and compatibility with PLA. Curcumin is a bioactive natural compound obtained from the root of Curcumin longa, known as turmeric [28]. Turmeric is used not only as coloring and flavoring agents in food processing, but also in the treat- ment of various diseases such as jaundice, cold and flu symptoms, ulcers, and anti-immune diseases [29]. Curcumin (diferuloylmethane), a hydrophobic phenolic substance, is the main bioactive compound in turmeric [30]. The chemical name of curcumin is 1,7-bis(4-hydroxy-3- methoxyphenyl)-1,6-heptadiene-3,5-dione [31]. Curcumin has attracted great attention recently due to its clinical value and pharmaco- logical application, such as wound healing, antioxidant, anti- International Journal of Biological Macromolecules 162 (2020) 1780–1789 ⁎ Corresponding author. E-mail address: jwrhim@khu.ac.kr (J.-W. Rhim). https://doi.org/10.1016/j.ijbiomac.2020.08.094 0141-8130/© 2020 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect International Journal of Biological Macromolecules journal homepage: http://www.elsevier.com/locate/ijbiomac