Development of microbiological test methods for the wooden packaging of foodstuffs
I Le Bayon, H Callot, M Kutnik, C Denis, A-M Revol-Junelles, J-B Millière, M Giraud, M Gabillé, N Passédat
Whereas different sampling methods already exist for analysing contaminated surfaces or packaging made of plastic or paper, there is no methodology that enables the sampling and quantification of microorganisms in packaging made of wood. The objective of this study was to compare the most commonly used microbiological methods and to develop a reliable quality control test adapted to wooden packaging of foodstuffs.
In the first step, poplar specimens were artificially contaminated with Bacillus stearothermophilus, Micrococcus luteus and Penicillium expansum. Then, we applied current sampling methods such as agar-contact plates, stomacher and ultrasonic sound and compared their efficiency. The results showed that only very low rates of viable microorganisms removal were possible with these methods.
Afterwards, we developed new methods that led to a high exchange between the contaminated wooden matrix and the diluent used to remove the microorganisms. The developed grinding-based method allowed to remove about 37% of the inoculated viable cells. An innovative method which consisted in coupling ultrasonic sound and vacuum pressure led to the removal of 72% of the viable cells. These new methods might promote the use of wood packaging for foodstuffs by providing an efficient quality control test as required by the existing regulations. They are now being validated.