Characterization of an antioxidant polylactic acid (PLA) film prepared with a-tocopherol, BHT and polyethylene glycol using film cast extruder Youngjae Byun, Young Teck Kim 1 , Scott Whiteside * Department of Packaging Science, Clemson University, B-212 Poole & Agricultural Center, Clemson, SC 29643-0320, USA article info Article history: Received 1 March 2010 Received in revised form 31 March 2010 Accepted 2 April 2010 Available online 9 April 2010 Keywords: Active packaging a-Tocopherol Polylactic acid (PLA) Antioxidant film Extrusion abstract Polylactic acid (PLA) films were prepared with a-tocopherol, buthylated hydroxytoluene (BHT), and poly- ethylene glycol 400 (PEG 400) using a cast film extruder in an effort to create an antioxidant film. Film properties were characterized by radical scavenging activity and thermal, physical, and gas barrier prop- erties. Final resin compounding and pelletization was achieved by a twin screw extruder and a pelletiz- ator to permit the homogenization of all resin components prior to film casting. Three different PLA films were fabricated for this study: pure PLA film, PLA film with BHT and PEG 400 (BP-PLA film), PLA film with a-tocopherol, BHT, and PEG 400 (ABP-PLA film). The addition of PEG 400 into the pure PLA film decreased the glass transition temperature (T g ) of the film. The BP-PLA and ABP-PLA film had around 51 °C of T g while pure PLA film had 66 °C. Due to the decreased T g of both the BP-PLA and ABP-PLA film, both films had an increased elongation at break (%E). The addition of plasticizer into the pure PLA film also caused increased water vapor permeability (WVP) and decreased oxygen permeability (OP). The ABP-PLA film had highest DPPH radical scavenging activity, 90%, while pure PLA and BP-PLA film had only 0 and 14%, respectively. Ó 2010 Elsevier Ltd. All rights reserved. 1. Introduction One of the major functions of a food packaging material is to protect the food products from various physical, chemical, biolog- ical and environmental conditions, such as oxygen, moisture, light, microorganisms, and physical stress. In recent years, there has been an increased demand for packaging that offers an improved shelf life for fresh, high quality food products. Active packaging has been developed in response to these demands. Active packag- ing is defined as the packaging that changes the conditions of the packed food to extend shelf life, to improve sensory properties, or to inhibit the growth of pathogenic and spoilage microorgan- isms (Ahvenainen, 2003). It involves the interactions between package and packaged food or headspace atmosphere by the incor- poration of certain additives into packaging film or within packag- ing containers (Day, 2003). Antioxidant packaging is a major category of the active packaging and very promising technique for extending food prod- uct shelf life. Some forms of food deterioration, such as the devel- opment of off-flavor, color and flavor changes, and nutritional losses, are caused by oxidation (Anklam et al., 1997; Morales-Aiz- purua and Tenuta-Filho, 2005). To prevent oxidation in food prod- ucts, several synthetic or natural antioxidants have been incorporated into the packaging film structure as an antioxidant packaging (Botterweck et al., 2000; Chen et al., 1992; Hamilton et al., 1997). Butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) are the most widely used synthetic antioxidants in the pre- vention of oxidation in food products. However, many consumers do not prefer these synthetic antioxidants due to their toxicity and suspected carcinogenic potential (Botterweck et al., 2000; Chen et al., 1992). From the safety and marketing point of view, a natural antioxidant is more attractive. a-tocopherol is a natural chain-breaking antioxidant with a positive consumer perception (Hamilton et al., 1997). In addition, it is very stable under conven- tional film processing conditions. a-tocopherol has been incorpo- rated into polymer materials as a stabilizer (Al-Malaika et al., 1994, 1999) and as an antioxidant in controlled release packaging to reduce the oxidation of a fatty food simulant (Siro et al., 2006). Wessling et al. (1999, 2000) have reported on the possibility of the antioxidant incorporation into the low density polyethylene (LDPE) and polypropylene (PP) as an active packaging material for various liquid food products and food simulants. Despite the fact that petroleum-based polymers are widely used in packaging industry, demand is increasing for alternative biodegradable poly- mers. Recently, fish and mammalian gelatin films containing natu- ral antioxidants were developed by film casting method (Gimenez 0260-8774/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jfoodeng.2010.04.005 * Corresponding author. Tel.: +1 864 656 6246; fax: +1 864 656 4395. E-mail address: wwhtsd@clemson.edu (S. Whiteside). 1 Author Young Teck Kim has equivalently contributed on this paper as a corresponding author. Journal of Food Engineering 100 (2010) 239–244 Contents lists available at ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng