Purpose: This study aimed at developing antimicrobial hydrogels which were made from whey proteins or its Maillard reaction products for food application.
Methods: Whey protein powder (1 to 5%) or Maillard reaction products (1 to 5%) from the reaction of hydrolyzed whey protein with sugars were mixed with water/dimethylsulfoxide (DMSO) solution at 1:0, 1:1, 3:7, 7:3, and 0:1 ratios. The mixtures were heated at 55°C overnight to precipitate proteins. Formed hydrogels were examined for properties (swelling, hardness, and elasticity) and antimicrobial loading capacity for grapefruit seed extract, citrus peel extract, and ε-polylysine. Eventually, the antimicrobial activity of the gels were evaluated to Listeria monocytogenes, Escherichia coli, Salmonella, and Bacillus cereus.
Results: Among combination of whey protein or Maillard reaction product concentrations with various ratios of water/DMSO, 3% whey protein with 0:1 ratio of water/DMSO and 3% Maillard reaction product with 0:1 ratio of water/DMSO had the most appropriate swelling, hardness, and elasticity. Regarding antimicrobial loading capacity, ε-polylysine was appropriate. Therefore, antimicrobial hydrogels (3% whey protein + 0:1 ratio of water/DMSO solution + ε-polylysine and 3% Maillard reaction product + 0:1 ratio of water/DMSO solution + ε-polylysine) were prepared and they showed antimicrobial activity against L. monocytogenes.
Significance: This result indicates that the developed antimicrobial hydrogels can be used to control L. monocytogenes in foods.