title: Lysozyme affects the microbial catabolism of free arginine in raw-milk hard cheeses.
abstract: Lysozyme (LZ) is used in several cheese varieties to prevent late blowing which results from fermentation of lactate by Clostridium tyrobutyricum. Side effects of LZ on lactic acid bacteria population and free amino acid pattern were studied in 16 raw-milk hard cheeses produced in eight parallel cheese makings conducted at four different dairies using the same milk with (LZ+) or without (LZ-) addition of LZ. The LZ-cheeses were characterized by higher numbers of cultivable microbial population and lower amount of DNA arising from lysed bacterial cells with respect to LZ + cheeses. At both 9 and 16 months of ripening, Lactobacillus delbrueckii and Lactobacillus fermentum proved to be the species mostly affected by LZ. The total content of free amino acids indicated the proteolysis extent to be characteristic of the dairy, regardless to the presence of LZ. In contrast, the relative patterns showed the microbial degradation of arginine to be promoted in LZ + cheeses. The data demonstrated that the arginine-deiminase pathway was only partially adopted since citrulline represented the main product and only trace levels of ornithine were found. Differences in arginine degradation were considered for starter and non-starter lactic acid bacteria, at different cheese ripening stages.
authors.affiliation: Department of Food, Environmental and Nutritional Sciences, University of Milan, Italy. Electronic address: paolo.dincecco@unimi.it.
authors.forename: P
authors.initials: P
authors.lastname: D'Incecco
authors.affiliation: Department of Food Science, University of Parma, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Gatti
authors.affiliation: Department of Food, Environmental and Nutritional Sciences, University of Milan, Italy.
authors.forename: J A
authors.initials: JA
authors.lastname: Hogenboom
authors.affiliation: Department of Food Science, University of Parma, Italy.
authors.forename: B
authors.initials: B
authors.lastname: Bottari
authors.affiliation: Department of Food, Environmental and Nutritional Sciences, University of Milan, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Rosi
authors.affiliation: Department of Food Science, University of Parma, Italy.
authors.forename: E
authors.initials: E
authors.lastname: Neviani
authors.affiliation: Department of Food, Environmental and Nutritional Sciences, University of Milan, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pellegrino
mesh_terms: D000818:Animals; D001120:Arginine / Q000032:analysis / Q000378:metabolism*; D002417:Cattle; D002611:Cheese / Q000032:analysis / Q000382:microbiology*; D005285:Fermentation; D005503:Food Additives / Q000494:pharmacology*; D005511:Food Handling; D007778:Lactobacillus / Q000187:drug effects / Q000378:metabolism*; D008892:Milk / Q000382:microbiology; D009113:Muramidase / Q000494:pharmacology*
chemical_list: D005503:Food Additives; D001120:Arginine; D009113:Muramidase
keywords: Arginine deiminase; Free amino acids; Lysozyme; Non-starter LAB; Raw milk cheese