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Physical evaluation of pure zein films by atomic force microscopy and thermal mechanical analysis


Biodegradable edible films can be made from corn protein, α-zein. Pure zein films are cast from an organic solution of α-zein. This report outlines the surface conditions of such pure zein films. First, the transition temperature, T t′ of the pure zein film was measured with a thermomechanical analyzer. T t was between 167.0 and 172.7°C. The thermal elongation of the films depended on the drying conditions used during film preparation. Second, the surface microstructure of pure zein films, produced under several different drying conditions, was observed by atomic force microscopy. The surface had a morphology that showed depressions either with acutely (90–120°) or obtusely (121–180°) angled features depending upon the drying conditions. On the other hand, the surface microstructure after thermal elongation analysis appeared to have a pattern of projections that was repeated every 25 nm. Third, we measured the contact angle of the pure zein films. We found a correlation between surface microstructure and contact angle. Pure zein films with projections smaller than 200 nm in base diameter on the surface had a high contact angle (>70°).

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  1. Japan Chemical Industry Association, A Study on Hormone-Like (Hormone-Mimic) Effects of Exogenous Substances—Shortened English Version, Japan Chemical Industry Association, Tokyo, 1997.

    Google Scholar 

  2. Krochta, J.M., Edible Protein Films and Coatings, in Food Proteins and Their Application, edited by S. Damodaran and A. Paraf, Marcel Dekker, Inc., New York, 1997, pp. 529–549.

    Google Scholar 

  3. Cuq, B., N. Gontard, and S. Guilbert, Proteins as Agricultural Polymers for Packaging Production, Cereal Chem. 75:1–9 (1998).

    CAS  Google Scholar 

  4. Argos, P., K. Pedersen, M.D. Marks, and B.A. Larkins, A Structural Model for Maize Zein Proteins, J. Biol. Chem. 257:9984–9990 (1982).

    CAS  Google Scholar 

  5. Shewry, P.R., and A.S. Tatham, The Prolamin Storage Proteins of Cereal Seeds: Structure and Evolution, Biochem. J. 267:1–12 (1990).

    CAS  Google Scholar 

  6. Yamada, K., H. Takahashi, and A. Noguchi, Improved Water Resistance in Edible Zein Films and Composites for Biodegradable Food Packaging, Int J. Food Sci. Technol. 30:599–608 (1995).

    CAS  Google Scholar 

  7. Tatham, A.S., J.M. Field, V. Morris, K.J. L'Anson, L. Cardle, M.J. Dufton, and P.R. Shewry, Solution Conformational Analysis of the α-Zein Proteins of Maize, J. Biol. Chem. 268: 26253–26259 (1993).

    CAS  Google Scholar 

  8. Matsushima, N., G. Danno, and Y. Izumi, Preliminary Small-Angle X-ray Scattering Study from Maize Zein Proteins, Rep. Prog. Poly. Phys. Japan. 37:631–632 (1994).

    Google Scholar 

  9. Matsushima, N., G. Danno, H. Takezawa, and Y. Izumi, Three-Dimensional Structure of Maize α-Zein Proteins Studied by Small-Angle X-ray Scattering, Biochim. Biophys. Acta 1339: 14–22 (1997).

    CAS  Google Scholar 

  10. Swallen, L.C., Zein—A New Industrial Protein, Ind. Eng. Chem. 33:394–398 (1941).

    Article  CAS  Google Scholar 

  11. Bernardi, D.J., Method of Drying Ink, U.S. Patent 2,285,183 (1940).

  12. Kroeger, J.W., and H.F. O'Connor, Printing Ink Containing Zein, U.S. Patent 2,366,970 (1941).

    Google Scholar 

  13. Katayama, H., H. Ishida, H. Yoshimoto, and M. Kanke, Evaluation of Zein Tablets for Sustained-Release Dosage from in vitro and in vivo, Drug Delivery Syst. 12:19–25 (1997).

    CAS  Google Scholar 

  14. Aydt, T.P., C.L. Weller, and R.F. Testin, Mechanical and Barrier Properties of Edible Corn and Wheat Protein Films, ASAE 34:207–211 (1991).

    CAS  Google Scholar 

  15. Yamada, K., A. Noguchi, and H. Takahashi, Effects of the Solvents on Properties of Zein, Nippon Shokuhin Kagaku Kogakukaishi 43:306–312 (1996).

    CAS  Google Scholar 

  16. Lai, H.M., G.W. Padua, and S. Wei, Properties and Microstructure of Zein Sheets Plasticized with Palmitic and Stearic Acids, Cereal Chem. 74:83–90 (1997).

    CAS  Google Scholar 

  17. Lai, H.M., and G.W. Padua, Properties and Microstructure of Plasticized Zein Films, ——Ibid. 74:771–775 (1997).

    CAS  Google Scholar 

  18. Lai, H.M., and G.W. Padua, Water Vapor Barrier Properties of Zein Films Plasticized with Oleic Acid, ——Ibid. 75:194–199 (1998).

    CAS  Google Scholar 

  19. Shewry, P.R., M.J. Miles, N.H. Thomson, and A.S. Tatham, Scanning Probe Microscopes—Applications in Cereal Science, ——Ibid. 74:193–199 (1997).

    CAS  Google Scholar 

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Correspondence to Seiichiro Isobe.

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Yoshino, T., Isobe, S. & Maekawa, T. Physical evaluation of pure zein films by atomic force microscopy and thermal mechanical analysis. J Amer Oil Chem Soc 77, 699–704 (2000).

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Key Words

  • Atomic force microscopy (AFM)
  • biodegradable film
  • contact angle
  • thermal mechanical analysis
  • zein film