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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Bacterial contamination of beef meat

The primary contamination of the meat surface of healthy animals is decisively influenced by the abattoir environment and the condition of the animal.

Varying levels of both Gram-positive and Gram-negative bacteria constitute the initial microbial population.

Bacterial presence is limited almost exclusively to the exterior surface of carcasses unless the surface has been penetrated by utensils allowing transport of bacteria to interior muscle tissues.

The hides of cattle are loaded with bacteria. The intestinal tract of cattle is also loaded with bacteria. Bacteria from intestinal tract may come in contact with the carcass surface if the intestinal tract is rupture during evisceration.

Also, feces during slaughter and rumen contents spilled through the esophagus may additional sources of contamination.

The important spoilage bacteria of fresh meat include Pseudomonas, Acinetobacter/Moraxella, Aeromonas, Alteromonas putrefaciens, Lactobacillus and Brochothrix thermosphacta.

The major end products of metabolism of common meat spoilage organisms are sulfides, amines, acetic acid, lactic acid, isovaleric acid, isobutyric acid, esters and nitriles.
Bacterial contamination of beef meat

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Strategies to Keep Food Safe

Reducing the risk of bacterial hazards:
*Wash hands before and after touching raw food.
*Use disposable tissues in food areas
*Keep fingernails short, free form polish and use a nail brush to clean them.
*Keep hair away from food
*Clean and sanitize all food contact surfaces that touch raw food.
*Clean and sanitize all cleaning cloths, sponges, equipment and utensils that touch raw food.
*Store raw foods on shelves below ready-to-eat foods to prevent cross-contamination.
*Remember, raw meats dripping on ready-to-eat foods will contaminate the ready-to-eat foods.
*Control of pathogens in animal reservoirs
*Control of pathogens during food production
*Improvement of food handling practices
*It is essential to thaw thoroughly any deep frozen raw food before cooking it
Strategies to Keep Food Safe

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