Growth and Enterotoxin Production of Staphylococcus aureus in Fresh Packaged Mushrooms (Agaricus bisporus)

Abstract

Freshly harvested mushrooms were found to induce a near-anaerobic environment (<2% O2) in unventilated, PVC-overwrapped packages within 2 to 6 h when incubated at 20 to 30°C. Mushrooms were inoculated with an enterotoxigenic strain of Staphylococcus aureus and incubated in overwrapped trays at different temperatures. S. aureus grew and produced staphylococcal enterotoxin (SE) in unventilated PVC-overwrapped mushroom packages when inoculated at levels of 103, 104, and 105 CFU/g of mushroom after 4 days of incubation at 30°C. Growth of S. aureus was observed at all levels of inoculation at 25°C, but no SE was detected after 7 days of incubation. When mushroom packages were ventilated, S. aureus growth was suppressed and no SE was detected after 7 days at 25°C and 4 days at 30°C. However, S. aureus growth in ventilated packs exceeded growth in unventilated packages when the incubation temperature was increased to 35°C; SE was detected within 18 h of incubation at this temperature, even in mushrooms inoculated at a low level (102 CFU/g). These results show the extreme importance of proper sanitation and worker hygiene during mushroom harvesting and packaging, ventilation of fresh mushroom packages, and proper storage temperatures for fresh mushrooms at all points of the food chain.

Behaviour of Listeria monocytogenes in packaged fresh mushrooms (Agaricus bisporus)

“…These results are in agreement with those reported by other authors (Lopez‐Briones et al . 1993; Martin and Beelman 1996; Tano et al . 1999).…”

Atmospheric Composition and Quality of Fresh Mushrooms in Modified Atmosphere Packages As Affected by Storage Temperature Abuse

“…may also germinate (Sugiyama and Yang, 1975). Furthermore, under near anaerobic conditions, enterotoxigenic S. aureus can grow and produce enterotoxin if packages were accidently exposed to surambient temperatures for prolonged periods (Martin and Beelman, 1996). The MA package in this study was not permeable to water vapor.…”

Effect of modified atmosphere packaging on the shelf-life of coated, whole and sliced mushrooms

“…Also, low O 2 decreased tyrosinase activity reducing enzymatic browning. Although a low concentration of O 2 may have many advantages, less than 2% could cause anaerobic microbial growth significantly, such as Clostridium botulinum (Herr, 1991) and Staphylococcus aureus (Martin & Beelman, 1996).…”