Growth potential of Clostridium botulinum in fresh mushrooms packaged in semipermeable plastic film.

Abstract

Fresh mushrooms (Agaricus bisporus) were inoculated in the stem, gill, or cap with Clostridium botulinum spores. They were placed with uninoculated mushrooms in paper board trays, which were then covered and sealed in a polyvinyl chloride stretch film to simulate prepackaged mushrooms available at retail stores. When incubated at 20 C, botulinum toxin could be detected as early as day 3 or 4, when the mushrooms still appeared edible. Mushrooms inoculated in the stem with 1,000 type A spores frequently became botulinogenic; higher spore levels were needed if gills or caps were inoculation sites. Type B spores were less apt to produce toxic mushrooms. Respiration of the fresh mushrooms used up 02 more rapidly than could enter through the semipermeable wrapping film, so that the equilibrium 02 concentration became low enough for growth of C. botulinum. Inoculated mushrooms did not become botulinogenic when held at 4 C.

The sensory and microbiological quality of fresh sliced mushroom (Agaricus bisporus L.) packaged in modified atmospheres

“…This indicates potential anaerobic pathogen growth as reported by other authors (Beit-Halachmy & Mannheim, 1992). Sugiyama & Yang (1975) detected botulinal toxin production in mushrooms inoculated with 5 · 10 3 CFU g )1 of C. botulinum type A, packed in non-perforated PVC at 20°C, in which O 2 levels below 2% were reached. Consequently, atmospheres with O 2 levels below 2% must be avoided and refrigeration conditions must be maintained.…”

“…Low CO 2 levels (2-6%) with 5% O 2 also have an inhibitory effect (Roy et al, 1995a). However, O 2 levels below 2% have been correlated with anaerobic respiration in mushrooms (Burton et al, 1987;Beit-Halachmy & Mannheim, 1992) as well as the accumulation of ethanol and acetaldehyde and the production of unpleasant odours (Tano et al, 1999); in addition low O 2 seems to encourage the potential growth of anaerobic pathogens (Sugiyama & Yang, 1975).…”

“…Different films have been used to pack mushrooms, the most common commercial packaging being perforated and non-perforated polyvinylchloride (PVC). By using non-perforated PVC films extremely low oxygen levels can be achieved, especially at room temperature (18-20°C) and an anaerobic atmosphere may result which is favourable to the growth of Clostridium botulinum (Nichols & Hammond, 1973;Sugiyama & Yang, 1975). Recent developments in packaging technology have led to the production of new films whose permeability can be chosen in advance (P-Plus micro-perforated films); these could be suitable for packing sliced mushrooms.…”

Growth and toxin production by non-proteolytic and proteolytic Clostridium botulinum in cooked vegetables

“…Growth and toxin production by proteolytic Cl. botulinum were also reported in other vegetable preparations such as incorrectly canned asparagus (Notermans 1993), fresh packed mushrooms (Sugiyama and Yang 1975), fresh packed shredded cabbage (Solomon et al 1990), and sautked onions (Solomon and Kautter 1986). For both proteolytic and non-proteolytic strains, growth and toxin production appeared to be related to the pH of the cooked purked vegetables.…”

Microbiological Consequences of Minimally Processed Fruits and Vegetables

“…In this case, the high repiratory activity of the mushrooms consumed oxygen. Because the film restricted transmission of oxygen back into the package, Clostridium botulinum was able to grow and produce toxin (Sugiyama and Yang 1975). Although this was discovered before cases of botulism resulted, the results could have been disastrous had the researchers not anticipated this possibility.…”