Effect of concentration of glutaraldehyde and glyoxal on binding lysozyme to zein based films to control foodborne pathogens in tomatoes

The demand for biodegradable packaging materials as an alternative to synthetic ones to reduce environmental cost has seen an increase in recent years. In addition, functionalizing the packaging film to provide specific advantages like antimicrobial properties has yet to be explored thoroughly. This study considers adding antimicrobial agents to improve the quality and safety of actively packaged fresh produce using an antimicrobial enzyme (lysozyme) immobilized on a biopolymer based packaging film (corn-zein). The developed packaging material is aimed as an active biodegradable packaging to reduce bacterial contamination on the surface of fresh organic produce, specifically tomatoes. The study uses glutaraldehyde and glyoxal as binding agents to immobilize the enzyme on the packaging film. The effect of concentration of glutaraldehyde and glyoxal on the controlled release of the enzyme was studied. Concentrations of 0.1 and 0.2 g/g lysozyme: cross linking agent had controlled release properties. However, concentrations of 0 or 0.05 are about 20-30% more effective at inactivating bacteria. Antimicrobial activity in the constructed zein films are also tested against selected pathogens (Salmonella Newport and Listeria monocytogenes). Developed zein based film is tested against inoculated tomatoes to determine the efficacy of the films in reducing the pathogen population. The inoculated tomatoes are stored at room temperature over a storage period of one week. The film was able to reduce Listeria monocytogenes population by three logs but was unable to reduce the population of Salmonella Newport.