Migration of a-tocopherol and resveratrol from poly(L-lactic acid)/starch blends films into ethanol Sung Wook Hwang a , Jin Kie Shim a,⇑ , Susan Selke b , Herlinda Soto-Valdez c , Laurent Matuana b , Maria Rubino b , Rafael Auras b,⇑ a Korea Packaging Center, The Korea Institute of Industrial Technology, Bucheon, South Korea b The School of Packaging, Michigan State University, East Lansing, MI 48823, USA c Centro de Investigación en Alimentación y Desarrollo, A.C., CTAOV, Hermosillo, Sonora 83304, Mexico article info Article history: Received 7 August 2012 Received in revised form 22 January 2013 Accepted 27 January 2013 Available online 8 February 2013 Keywords: PLLA Starch a-Tocopherol Resveratrol Blends abstract Poly(L-lactic acid) (PLLA)/starch blends with various concentrations of two natural antioxidants, a- tocopherol (a-TOC) and resveratrol, were fabricated by a melt blending and compression molding pro- cesses. The effects of the two antioxidants on the optical (color), thermal and mechanical properties of PLLA/starch blends with antioxidants were assessed. PLLA/starch blend films with a-TOC and resveratrol showed a yellowish color influenced by the combined effect of white starch and the brown color of the antioxidants. The glass transition and melting temperatures were significantly reduced with the addition of antioxidants while enhanced thermal stability was observed, which could be a benefit and important for processing and production. The enhanced mechanical properties could be attributed to not only a compatibilization effect based on the chemical linkage between PLLA and starch chains, but also restriction of the chain mobility by antioxidants. The release of resveratrol from PLLA and PLLA/starch blend films into ethanol followed Fickian behavior. The D values of a-TOC were in the range of 0.47–3.95  10 11 cm 2 s 1 for PLLA films and 0.70–6.83  10 11 cm 2 s 1 for PLLA/starch blend films at 13 °C, 5.67–13.0  10 11 cm 2 s 1 for PLLA films and 4.10–24.2  10 11 cm 2 s 1 for PLLA/starch blend films at 23 °C, and 89.0–118.0  10 11 cm 2 s 1 for PLLA films and 123–282  10 11 cm 2 s 1 for PLLA/starch blend films at 43 °C. The D values of resveratrol were in the range of 0.073–0.54  10 10 cm 2 s 1 for PLLA films and 1.42–6.93  10 10 cm 2 s 1 for PLLA/starch blend films at 13 °C, 0.90–3.44  10 10 cm 2 s 1 for PLLA films and 4.16–22.3  10 10 cm 2 s 1 for PLLA/starch blend films at 23 °C, and 24.8–74.1  10 10 cm 2 s 1 for PLLA films and 40.1–309  10 10 cm 2 s 1 for PLLA/starch blend films at 43 °C. Ó 2013 Elsevier Ltd. All rights reserved. 1. Introduction The development of new types of polymers synthesized from natural renewable resources has been widely investigated. Poly(lac- tic acid) (PLA) is one of the most promising polymers due to its bio- compatibility and biodegradability (Auras et al., 2004; Lim et al., 2008). The global lactic acid and PLA market is expected to grow by about US $3.8 billion by 2016 (Markets and Markets, 2011). PLA is currently used for single or multilayer films, trays, cups, and bot- tles, and can be manufactured by extrusion, thermoforming, injec- tion and blow molding processes for packaging applications. PLA is also suitable for the production and use of functional membranes (Auras et al., 2004; Manzanarez-López et al., 2011; Soto-Valdez et al., 2011). Although PLA shows good physical properties similar to polystyrene (PS) and polyethylene terephthalate (PET), the relatively high oxygen permeability of PLA and its brittleness are main drawbacks for flexible packaging applications, especially for foods and/or pharmaceuticals products susceptible to oxidation. Controlled release systems have been developed and are exten- sively being used in pharmaceutical, food and packaging applica- tions (Brayden, 2003). Specifically, these have been used in drug delivery systems. Application of these systems to food packaging has increased since they enable controlled release of active com- pounds such as antioxidants and antimicrobials from the packag- ing system at an appropriate rate during the storage of products, allowing protection and extension of the product’s shelf life. One of the first applications of this technology was reported to extend the shelf life of oatmeal cereal packaged in high density polyethyl- ene (HDPE) film with a high concentration of added butylated hydroxytoluene (BHT) (Miltz et al., 1988). Wessling et al. studied the migration and sorption behavior of a-Tocopherol (a-TOC) and BHT in low density polyethylene (LDPE) in contact with a fatty food simulant, and found that the migration of a-TOC into the food simulant was slower than that of BHT (Wessling et al., 1998). Byun 0260-8774/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jfoodeng.2013.01.032 ⇑ Corresponding authors. Tel.: +82 032 624 4758; fax: +82 032 624 4770 (J.K. Shim), tel.: +1 517 432 3254, +1 517 355 0172; fax: +1 517 353 8999 (R. Auras). E-mail addresses: jkshim@kitech.re.kr (J.K. Shim), aurasraf@msu.edu (R. Auras). Journal of Food Engineering 116 (2013) 814–828 Contents lists available at SciVerse ScienceDirect Journal of Food Engineering journal homepage: www.elsevier.com/locate/jfoodeng