TABLE 2.

Selected publications regarding the effects of lysozyme addition on the microbial properties of cheese.

Cheese type	The mode of lysozyme application and experiment condition	Lysozyme concentration	Target microorganism	Outcome	References
Model cheeses	Lysozyme added into milk in combination with high hydrostatic pressure (HHP) (60 MPa/210 min/30°C + 400 Mpa/15 min/30°C	(22.4 mg/L)	Spores of B. cereus ATCC 9139	Lysozyme did not enhance the sensitivity of the spores to HHP	(30)
Traditional French goat cheese	Human lysozyme transgenic goat milk	270 μg/mL	Lactococci, streptococci, enterococci and Lactococcus spp.	Lysozyme transgenic goat milk did not adversely affect the growth of lactic acid bacteria during the cheese-making process. Due to inactivation of lysozyme by pasteurization at 74°C, transgenic technology and lysozyme transgenic goat milk had the potential to improve the safety of raw milk cheese production.	(28)
Mozzarella cheese	Chitosan composite film containing lysozyme storage at 10°C for 14 and 30 days for bacteria and mold, respectively	60% lysozyme in chitosan film-forming solutions	L. monocytogenes, E. coli, P. fluorescens, mold and yeast	Incorporation of 60% lysozyme in chitosan film-forming solutions exhibited greater antimicrobial effect than chitosan alone. The growth of L. monocytogenes, E. coli, P. fluorescens and mold in Mozzarella cheese decreased by application of chitosan-lysozyme composite films and coatings	(65)
Cheese curd	Native, heat- treated and dextran-conjugated lysozyme Ripening at 4°C for 40 days	400 μg/mL	E. coli and S. aureus	Lysozyme and modified enzymes were effective against E. coli. However, the lysozyme-dextran conjugate decreased the populations of E. coli by 3 log in cheese curd after 40 days of storage, indicating the improvement of antimicrobial activity of the lysozyme-dextran conjugate against Gram-negative bacteria. Both lysozyme and modified enzymes were similarly effective against S. aureus and conjugation with dextran did not increased antimicrobial activity of lysozyme against S. aureus.	(62)
Mozzarella cheese	Lysozyme in diluted brine in combination with Na2-EDTA (10, 20 and 50 mmol/L) Storage at 4°C for 8 days	0.25 mg/mL	Total coliforms, Pseudomonadaceae and lactic acid bacteria	Lysozyme and Na2-EDTA significantly prevented the growth of coliforms and Pseudomonadaceae during the first 7 days of storage. Lactic acid bacteria were not affected by the addition of these active compounds.	(59)
Burrata cheese	Direct addition of lysozyme and Na2-EDTA (50 mM) with or without modified-atmosphere packaging storage at 8°C for 9 days	125, 250 and 500 mg/kg	Total microbial count, psychrotrophic microflora, lactic acid bacilli, yeasts and molds, total coliforms, Enterobacteriaceae, Pseudomonas spp.	Combination of lysozyme/Na2-EDTA and MAP resulted in higher microbiological acceptability limit (days) for coliforms and Pseudomonas spp. Cheese shelf life was prolonged by the combination of lysozyme/Na2-EDTA and MAP, especially at the highest lysozyme concentration	(63)
Iraqi soft cheese	Addition of lysozyme to the curd of soft cheese. Storage at 6°C for 15 days	250 and 300 mg/kg	Total count of bacteria, psychrophilic bacteria, yeast and mold	Enzyme addition led to a reduction in the development of tested bacteria in comparison to the untreated sample. The higher lysozyme, the better prolonged the shelf life. The highest scores in terms of texture, flavor and bitterness were observed in the sample containing 300 mg/kg lysozyme	(27)
Coalho cheese	Nano-laminate coating containing lysozyme storage at 8°C for 20 days	0.2% (w/v)	Mesophilic and psychotropic microorganisms	The shelf life of Coalho cheese was increased by application of nano-laminate coating containing lysozyme and coated cheese showed lower peroxidation of lipid and microorganisms’ proliferation	(68)
Gouda cheese	Composite edible film whey protein porang flour containing lysozyme ripening for 8 weeks	0, 0.05, and 0.1%	Aerobic plate count, Lactic acid bacteria, Enterococcus, Coliform, E. coli, Salmonella, S. aureus and yeast/mold	Native microbial population of coated gouda cheese such as aerobic plate count, lactic acid bacteria, enterococcus, and coliform was not significantly affected by modified lysozyme addition in composite edible. Although the population of native microbial gradually decreased in coated-Gouda cheese, the population of artificial pathogen contamination decreased faster at the beginning of cheese ripening. Generally, composite edible film containing lysozyme was able to prevent the growth of microorganisms both at the surface and inside the region of Gouda cheese during ripening.	(67)
Halloumi cheese	Chitosan coating with or without lysozyme cheese was held at 3°C or 25°C in 5%, 10% or 15% (w/v) NaCl for 18 h.	Lysozyme stock solution was prepared by dissolution at 10% (w/v) in distilled water with the addition of 25% (w/w) glycerol/lysozyme). The lysozyme solution was then mixed with the chitosan solution at a concentration of 60% (w/w) lysozyme/chitosan	Mesophilic, psychrotrophic, anaerobic, LAB, yeasts and molds	Coating increased the shelf-life of cheese without any adverse effect on the sensory properties of cheese. By using chitosan-lysozyme coating, the brine could be reduced from 15% to 10% while the same inhibitory effects against most contaminating microorganisms was obtained. Using chitosan-lysozyme coating in the production of Halloumi cheese, the brine could be reduced from 15 to 10% while the same inhibitory effects against most contaminating microorganisms and shelf-life would be achieved	(66)
Dangke (fresh soft cheese)	Immersion of dangke in various preservation solutions (lysozyme, lactoperoxidase and combination of lactoperoxidase and lysozyme) at 30°C for 10 min storage at 30°C for 18 h	–	Total microbial count	The highest bacterial count at 0 h was observed in the sample immersed in pure sterile water. The combination of lactoperoxidase system and lysozyme could inhibit the growth of microbes in dangke stored for 8 h.	(64)
Ultra-filtrated white cheese	Whey protein-based edible coating containing lysozyme-xanthan gum conjugate. Microbial properties was studied during 28 days storage at 8°C	200, 400, and 500 ppm lysozyme-xanthan conjugate	P. Chrysogenum, E. coli O157: H7, S. aureus, and starter activity	The growth of tested microorganisms was inhibited by application coating incorporating lysozyme-xanthan gum conjugate in comparison to uncoated cheese. Lactic acid bacteria were not affected by edible coating during 60 days of ripening. It has been stated that whey protein-based edible coating could be utilized as a carrier of lysozyme-xanthan to improve the shelf life of ultra-filtrated cheese.	(69)