Biofilm Ecology of Wooden Shelves Used in Ripening the French Raw Milk Smear Cheese Reblochon de Savoie

Abstract

Little work has been carried out on the microbiology of wooden shelves supporting cheese during ripening, and the safety of their use during cheese ripening has frequently been asked. Microbial characterization (enumerations on specific growth media) and description of their physicochemical conditions (pH, water activity, and salt concentration) were determined on 50 wooden shelves of 3 different ages at the end of the cheese-ripening process, using cheeses from 8 farm producers. The experiments were performed during 2 different seasons (summer and autumn). Micrococci-corynebacteria and yeasts and molds were found to be the dominant microflora on the shelves. Leuconostocs, facultative heterofermentative lactobacilli, enterococci, staphylococci, and pseudomonads were also found but at lower levels. There was no statistical difference in the major microflora between shelves of different ages. Moreover, the total counts and the predominant microflora showed a surprising homogeneity between origins of cheeses. For most of the microflora enumerated, no seasonal variation was observed. Regardless of the age of the shelves, the wood had high water activity values (0.94 to 0.97), neutral pH values (7.1 to 8.3), and low salt contents (0.11 to 0.17 mg/cm2). The origins of the cheese had a statistically significant impact on water activity, pH, and salt concentration, whereas the age of the shelves did not influence these parameters. This study demonstrated the stability of the technological biofilm present on wooden shelves and will serve to enlarge the debate on the use of wood in cheese ripening.

Persistence of wild Streptococcus thermophilus strains on wooden vat and during the manufacture of a traditional Caciocavallo type cheese

“…Recently, it has been demonstrated that the wooden surfaces of the vats used for the production of Ragusano PDO cheese are contaminated by microorganisms, in particular LAB, with concentrations varying between 10 3 and 10 6 CFU per square centimeter (Licitra et al, 2007;Lortal et al, 2009). Although other equipment, such as wooden shelves used for ripening, maybe the source of living microorganisms (Mariani et al, 2007), the equipment playing a key role during cheese production is undoubtedly the vat hosting milk. For this reason, in the present work the internal surfaces of the wooden vat were analyzed for the same microbial groups counted for milk, curd and whey samples.…”

Facility-Specific “House” Microbiome Drives Microbial Landscapes of Artisan Cheesemaking Plants

“…In modern cheese production facilities, biofilms of psychrotrophic bacteria (3,4) and nonstarter lactic acid bacteria (5)(6)(7)(8) can form on equipment surfaces, acting as a source of contamination in successive batches of cheese. Wooden processing surfaces, including aging boards (9,10) and milk vats (11)(12)(13), are also rich sources of microbes that are important for cheese acidification and ripening. In traditional cheesemaking facilities, adventitious microbes inhabiting such equipment surfaces can represent a "house" microbiota important for the development of specific cheese characteristics (14).…”

Examination of wooden shelves used in the ripening of a raw milk smear cheese by FTIR spectroscopy

“…However, little work has been carried out to identify the microorganisms present. In a recent study, Mariani et al (2007) identified micrococci-corynebacteria, yeasts and moulds as dominant microflora on the shelves used in ripening the French raw milk smear cheese Reblochon de Savoie at the end of the cheese-ripening process. Since safety of their use has frequently been asked, the influence of the presence of the native multi-species biofilm present on wooden shelves on the behaviour of two Listeria monocytogenes strains was analysed: an inhibitory effect of their growth was observed only on wooden ripening shelves colonised by living native biofilms (Mariani et al, in press).…”