Development of New Antioxidant Active Packaging Films Based on Ethylene Vinyl Alcohol Copolymer (EVOH) and Green Tea Extract

Abstract

Ethylene vinyl alcohol copolymer (EVOH) films containing green tea extract were successfully produced by extrusion. The films were brown and translucent, and the addition of the extract increased the water and oxygen barrier at low relative humidity but increased the water sensitivity, the glass transition temperature, and the crystallinity of the films and improved their thermal resistance. An analysis by HPLC revealed that the antioxidant components of the extract suffered partial degradation during extrusion, reducing the content of catechin gallates and increasing the concentration of free gallic acid. Exposure of the films to various food simulants showed that the liquid simulants increased their capacity to reduce DPPH(•) and ABTS(•+) radicals. The release of green tea extract components into the simulant monitored by HPLC showed that all compounds present in the green tea extract were partially released, although the extent and kinetics of release were dependent on the type of food. In aqueous food simulants, gallic acid was the main antioxidant component released with partition coefficient values ca. 200. In 95% ethanol (fatty food simulant) the K value for gallic acid decreased to 8 and there was a substantial contribution of catechins (K in the 1000 range) to a greatly increased antioxidant efficiency. Kinetically, gallic acid was released more quickly than catechins, owing to its faster diffusivity in the polymer matrix as a consequence of its smaller molecular size, although the most relevant effect is the plasticization of the matrix by alcohol, increasing the diffusion coefficient >10-fold. Therefore, the materials here developed with the combination of antioxidant substances that constitute the green tea extract could be used in the design of antioxidant active packaging for all type of foods, from aqueous to fatty products, the compounds responsible for the protection being those with the higher compatibility with the packaged product.

Potential of Lignins as Antioxidant Additive in Active Biodegradable Packaging Materials

“…This has been shown for hydroxyl radicals in the gas phase scavenged by essential oils supported on silanized glass wool and active packaging films containing essential oils [69]. The principle has been applied in the examples of use of catechins in poly(ethylene terephthtalate) [70] and catechins [71] or flavonoids in ethyl vinyl alcohol in using an adapted ORAC assay [72]. Although different methods exist to measure the radical scavenging activity of plastic films, the antiradical activity of the PLA-lignin film extracts was tested here with the help of the DPPH test, because it is readily available, largely used in literature and has already been employed for lignins [15].…”

Release of active compounds from agar and agar–gelatin films with green tea extract

“…Green tea polyphenols have been reported to act as antioxidants by donation of hydrogen atoms, acceptors of free radicals, interrupters of chain oxidation reactions or by chelating metals (Gramza & Korczak, 2004), and they have shown inhibitory effects in vitro against food spoilage and pathogenic microorganisms (Hamilton-Miller, 1995;Perumalla & Hettiarachchy, 2011). Furthermore, green tea extract has been already incorporated in food products to extend its shelf life (Gramza-Michalowska & Regula, 2007;Martín-Diana, Rico, & Barry-Ryan, 2008;Wanasundara & Shahidi, 1998), and more recently it has been used as active compound in packaging films (Chiu & Lai, 2010;López-de-Dicastillo et al, 2011;Siripatrawan & Noipha, 2012). However, the successful use of green tea extract as source of antioxidant and antimicrobial compounds in packaging films greatly depends on the ability of these compounds to migrate from the film matrix to the food.…”

Mathematical modeling of gallic acid release from chitosan films with grape seed extract and carvacrol

“…Moreover, Lopez de Dicastillo et al [33], also reported that gallic acid was the main antioxidant component released into aqueous food simulants from packaging films based on ethylene vinyl alcohol copolymer (EVOH) with added green tea extract. Gallic acid showed a faster diffusivity in the polymer matrix as a consequence of its smaller molecular size and its good solubility in …”