Applications for Shelf-Life Extension
The use of antimicrobial enzymes is a natural means to control microbial contamination, improving safety and shelf life of dairy products. Most applications involve lysozyme and lactoperoxidase, although new perspectives are arising from studies on lactoferrin.
Lysozyme is a peptidoglycan N-acetylmuramoylhydrolase, and its antimicrobial activity is based on damage of bacterial cell wall by catalyzing hydrolysis of the peptidoglycan components (Masschalck & Michiels, 2003). It is mainly effective against Gram-positive bacteria; nevertheless, recent reports demonstrated that when lysozyme is used in combination with ethylenediaminetetraacetic acid (EDTA), the antimicrobial spectrum greatly increases (Branen & Davidson, 2004; Sinigaglia et al., 2008). Unfortunately, addition of EDTA in dairy products is not yet permitted in many countries, and lysozyme can be used for preventing the growth of Bacillus cereus, a food pathogen also causing off-flavors, and the defect called late blowing by Clostridia in hard cheeses. The main source is hen egg white, and even though a study of Iaconelli et al. (2008) on Grana Padano reported that the amount of lysozyme absorbed by eating this type of cheese is very low, nutrition labels for products that use lysozyme must include it as a potential allergen.