Potential microbiological hazards in the production of refined paper products for food applications

This study sought to investigate the significance of raw materials (starch-based glues, raw material papers) at different microbiologically critical stages in the manufacturing process of refined paper products. The study examined the occurrence of microorganisms in the process and in end-product samples. Microbiological surveys verified that the production and use of pasteurized starch-based glue was the most important factor threatening the process hygiene and product safety. Subsequently, the production and use of starch-based glue was changed, and a follow-up programme targeting the microbiological quality of glue was developed as part of a hygiene and safety management system. A total of 33 spore-forming bacterial and 15 enterobacterial isolates were ribotyped, and 22 and 10 different ribogroups ( ribotypes), respectively, were generated. These isolates from starch-based glue, raw material paper and end products were atypical and, thus, in many cases physiological, chemotaxonomic (FAME) and molecular ( partial 16S rDNA) results did not correspond. The most common spore-forming bacteria (55% of the isolates) were Paenibacillus sp. and within this genus several new species were also proposed. The most common enterobacteria (87%) were Enterobacter cloacae and Citrobacter freundii belonging to bacteria in hazard group 2, or species closely related to them. It was demonstrated that the same spore-forming bacteria (ribotypes) were present in both the glue samples and the end products (45% of isolates).