Handbook of Hygiene Control in the Food Industry

Table 24.1

Important potential contaminants in the paper and packaging industry

and their characteristics

Characteristics

Bacillus

spp.

Clostridium

spp.

Sulphate-reducing bacteria (SRB)

Growthrequirements

Aerobic, facultative anaerobicTemperature optimum 25±45 ÎC, alsopsychrophilic and thermophilic strainsWide pH range

Strictly anaerobic, somemicroaerophilic speciesTemperature optimum 30±37 ÎC or40±45 ÎC, also thermophilic speciesthat can grow even at 80 ÎCpH optimum pH 6.5±7.0 for mostspecies

Strictly anaerobic speciesTemperature optimum 30±40 ÎC,also thermophilic species that cangrow even at 80 ÎC

Formation ofspores

Formation of endospores which are resistantto, e.g., heat, desiccation, disinfectants,radiation and ultraviolet light

Formation of endospores

Members of

Desulfotomaculum

genus produce endospores

Pathogenesis

Same species are pathogenic, e.g.

Bacillus

cereus

causes food poisoning

Several pathogenic species, e.g.,Clostridium perfringens, C. botulinum,C. tetani, C. difficile, C. paraputricum

Non-pathogenic species

Other problems Often involved in biofilm and slime

formationSome produce starch degrading enzymescausing, e.g., spoilage of raw materials usedin paper manufacturing

Production of hydrogen (H

) and 2

volatile organic fatty acids, e.g.butyric, propionic and valeric acids:Offensive odours and explosive gases

Reduction of sulphur compoundsto hydrogen sulphide (H

S) 2

Cause odour problems andcorrosion of stainless steels

Habitat, livingenvironment

Widely distributed in the environmentespecially soil and waterCommon in conifer trees used in papermanufacturingOften detected in vegetable and cerealproducts

Common in soil, anaerobic fresh watersediments, intestinal tracks of humanand domestic animalsOften detected in vegetable andanimal product

Common in anaerobic watersediments, intestinal tracks ofhuman and animals

Appearance inpaper industryenvironment

Detected in circulating waters, mechanicalpulp, papermaking chemicals, broke, slime,end-product

Detected in circulating waters, broke,slime, end-product

Detected in circulating waters,broke, kaolin, starch, slime