Preliminary study of physical and antibacterial properties of films of modified oats starches mixed with chitosan

One physical modification (autoclaving) and five chemical modifications (lintnerization, crosslinking, acetylation, hydroxypropylation, and oxidation) were performed on the native oat starch. The starches were mixed with chitosan (Ch) and plasticizer (glycerol) to make films. The film -forming solutions (FFS) were characterized rheologically and evaluated for physical properties (color, thickness, humidity and solubility), water vapor and oxygen permeability (10 and 25 degrees C), and mechanical properties. Antibacterial activity was evaluated against Escherichia coli, Staphylococcus aureus and Listeria monocytogenes by the agar diffusion. The functionality of the films as packaging in ground pork was evaluated by counting fecal coliforms and total aerobes for 21 days at 4 degrees C. All the FFS presented a pseudoplastic-type behavior. The addition of Ch increased the stress at fracture (TF) and decreased the percentage elongation (% E) in all the films; being the Oxidized -Ch formulation the one that presented the greatest increase (approximate to 200 %) in TF and the smallest decrease (38 %) in % E. All formulations with Ch presented antibacterial activity, which was higher in the Oxidized -Ch film and decreased with the evaluation time. The results generally indicated that the Oxidized-Ch film may represent a suitable formulation as antibacterial packaging with adequate physical, mechanical, and barrier properties.