Plasticized protein coatings on polypropylene (PP) film were prepared and examined for their optical and tensile properties as affected by protein and plasticizer types in order to exploit a novel composite film for food packaging applications. Composite structure of IT film coated with three kinds of proteins (soy protein isolate: SPI, whey protein isolate: WPI, corn zein: CZ) and various plasticizers (propylene glycol, glycerol, polyethylene glycol, sorbitol, sucrose) could be obtained by a simple casting method. High glossy surfaces were observed on the coated films with WPI and CZ, with the sucrose-plasticized WPI coating giving the highest gloss. Proteins as well as plasticizers exerted a noticeable effect on color of the coated films. WPI coated films also showed greater transparency and tensile strength than the other coated films. Nisin-incorporated WPI coatings on PP film exhibited significant bacterial growth inhibition against Lactobacillus plantarum. Results suggest that WPI coatings with a proper plasticizer possess excellent visual and mechanical characteristics and have great potential for application in active packaging systems. (C) 2007 Elsevier Ltd. All rights reserved.