Food spoilage: Staphylococcus aureus in hams and it products

Spoilage for raw hams can be caused by a variety of bacteria growing within the meat before the salt concentration is sufficiently high and/or if the initial curing temperature is not sufficiently low to prevent multiplication.

The reason why ham products are frequently involved is that in their preparation they may contaminated with Staphylococcus aureus, and since this product contains 2-3% salt, other bacteria might grow and inhibit the growth of staphylococci are themselves inhibited by the salt.

Staphylococcus aureus is able to grow and produce enterotoxin on slices of raw of the aw is above 0.90. Values of aw above 0.90 are usually associated with the production of ham from high pH meat. Values of aw above 0.90 should be stored refrigerated.

Dry-cure hams, after salting and before ripening, are washed to remove excess salt. If the washed hams are dried at the elevated temperatures (e.g. 30 °C) high number of Staphylococcus aureus can develop on the surface.

Tests in both media and raw pork showed that Staphylococcus aureus growth can occur in any combination of salt, nitrate and nitrite that is palatable and permissible. Staphylococcus also die rapidly in ham curing pickle unless protected by meat juices.

To reduce Staphylococcus aureus food poisoning, the amount of manual handling should be minimizes. Slicers should be dismantled when cleaned and sanitized. Ham should be sliced when it its cold. Rapid cooking should be permitted by storing food in small, loosely covered containers.
Food spoilage: Staphylococcus aureus in hams and it products

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Staphylococcus aureus and food poisoning

Staphylococcus aureus is an aerobic or anaerobic, non motile, non-spore-forming, catalase and coagulase-positive, gram-positive coccus, usually arranged in grapelike irregular clusters.

Staphylococcus aureus is an organism that may produce a very heat stable enterotoxin when permitted to grow to an elevated level (>100000 organism/g).

The foodborne intoxication is caused by ingesting enterotoxin produced in food by some strains of S.aureus, usually because the food has not been handled properly or cold enough.

The consumption of foods containing S. aureus toxins can lead to enterotoxin food poisoning within a few hours. The organism can grow at an Aw of 0.86 and in high salt concentrations.

Hand contact is by far the most common route of transmission, inadequate hygiene can lead to contamination of food.

Proper preprocessing handling of raw materials is essential. If conditions allow the organism grow and produce enterotoxin, subsequent thermal processing will destroy the organism while the heat stable toxin persists.

There is evidence that these enterotoxin may be not completely inactivated at retort temperatures (121C or 250F).

S. aureus typically exists as a commensal bacterium, colonizing the human body without causing infection. It is an opportunistic pathogen having the ability to cause infection when the opportunity presents itself.

The symptoms of poisoning include nausea, vomiting, abdominal cramps, and diarrhea, These first occur between 1 and 8 hours after consumption of contaminated food.

HACCP plans should provide for proper handling of raw materials, steps to destroy eliminate or reduce the hazard, and controls to prevent recontamination.

Staphylococcus aureus and food poisoning

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