| This study was conducted to determine the effect of protein type, plasticizer type, and protein to plasticizer concentration on properties of casein-based films, and then applying films to a food system. Films were produced from lactic acid or rennet precipitated casein, and either sorbitol or glycerol, mixed in distilled water. A lactic acid casein and sorbitol film and a lactic acid casein and glycerol film were used to wrap processed cheese slices, with low density polyethylene (LDPE) wrapped and unwrapped samples used as controls. Films were tested for barrier properties, water vapor and oxygen permeability, and mechanical properties, elongation and tensile strength. The cheese slices and films were tested for moisture content and color change over a 30 day storage period (2.2{dollar}spcirc{dollar}C, 88% relative humidity).; Films produced displayed good oxygen barrier properties, but poor water barrier properties compared to synthetic films. Films made with sorbitol exhibited significantly better (p {dollar}<{dollar} 0.05) water barrier and tensile properties than those made with glycerol. Higher protein concentrations also produced stronger films. Processed cheese slices wrapped in casein-based films lost a significant amount of moisture (p {dollar}<{dollar} 0.05) as compared to the LDPE wrapped control slices, which was the cause of a significant color change (p {dollar}<{dollar} 0.05) of the cheese slices. However, moisture lost by the cheese slices was retained in the casein-based films, shown by a large increase in moisture content of these films. |
