Lysozyme release from isolate pea protein and starch based films and their antimicrobial properties

- The effect of the polymer matrix and temperature on the release of lysozyme was studied.
- A loss of lysozyme activity was observed after film formation.
- Diffusion of lysozyme was enhanced when temperature increased.
- Lysozyme acts mainly at the food surface due to its high molecular weight.
- The effectiveness of films containing lysozyme, against Listeria monocytogenes was proved.

The objective of the current research was to analyze the effects of the pea protein and corn starch films as well as the temperature influence (10 and 25 °C) on the release of lysozyme to a food simulant (agar gel). Lysozyme concentration at different depths of food simulant was measured, as a function of diffusion time, through its enzyme activity. In both polymer matrices, a loss of lysozyme activity was observed after film formation. Diffusion of lysozyme was enhanced when temperature increased, mainly when pea protein films were tested. A higher retention of lysozyme in the film starch matrix was significantly detected which could be attributed to the different hydration degree of the film in contact with the agar medium and the different interactions between the enzyme and the film polymer chains. The antimicrobial effectiveness of pea protein and starch films containing lysozyme (0, 50, 75 and 100 mg lysozyme/g hydrocolloid), against Listeria monocytogenes was proved. At 10 °C, both matrices were effective against the pathogen. At 25 °C, the effectiveness of films significantly decreased and pea protein films showed the best antimicrobial activity.