DOI: 10.1094/CC-82-0009 |  VIEW ARTICLE

Physical, Mechanical, and Barrier Properties of Kafirin Films from Red and White Sorghum Milling Fractions.

Laura S. da Silva (1) and John R. N. Taylor (1,2). (1) Department of Food Science, University of Pretoria, Pretoria 0002, South Africa. (2) Corresponding author. Phone: +27 12 420 4296. Fax: +27 12 420 2839. E-mail: <jtaylor@postino.up.ac.za> Cereal Chem. 82(1):9-14. Accepted August 5, 2004. Copyright 2005 American Association of Cereal Chemists, Inc.

Fractions from the sorghum dry milling industry, including bran, are a potential source of kafirin. Free-standing plasticized cast films were prepared from defatted kafirin preparations from red and white sorghum flour and bran fractions, and from commercial zein. All the kafirin preparations were able to form films. However, there were differences in film thickness, clarity, flexibility, surface texture, odor, and color between the different kafirin films. Bran kafirin films were highly colored, less flexible with a less smooth surface texture compared with films from flour, probably due to higher levels of contaminants in the bran kafirins. The strong color of the bran films could limit their use in certain coating applications. The kafirin films had much higher tensile strength and lower extensibility than zein film, probably because of the presence of beta- and gamma-kafirins in the kafirin, giving high levels of disulfide cross-linking in the kafirin films. The kafirin films had poorer water barrier properties than zein film, possibly due to greater thickness or to poorer flexibility, which may have caused microcracks.