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

The surface of wooden shelves used in the ripening of a raw milk smear cheese was examined by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. FTIR spectra of zones of wooden shelves in contact with cheeses or not (control) were acquired. This acquisition was performed either directly after cheeses removal or after brushing with water to remove cheese compounds deposited onto wood surfaces. Their analysis revealed that the degree of similarity between the ATR-FTIR spectra of unused and cleaned by brushing wooden shelves is higher than with the spectra of non-cleaned surfaces. The spectra of non-cleaned zones where cheeses were ripened namely differed in the 920–1180 cm−1 and in the 1485–1780 cm−1 regions. These regions can be assigned to proteins and polysaccharides and thus might correspond to deposits of cheese rind surface as well as to the presence of microbial biofilms on wooden shelves. Similarities in these spectral regions with those of cheese rind support this hypothesis. These observations indicate that ATR-FTIR spectroscopy is a rapid and valuable analytical tool to directly investigate the global chemical composition of very thin films such as microbial biofilms or cheese rind deposits present on wooden shelves which are not accessible to standard chemical methods.