Time-Temperature Effects on Salmonellae and Staphylococci in Foods: II. Thermal Death Time Studies (2024)

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Time-Temperature Effects on Salmonellae and Staphylococci in Foods: II. Thermal Death Time Studies? ›

the type studied to 150 F and holding every particle of food at this temperature for at least 12 min reduces 10 million or less salmonellae or staphylococci per gram to nondetectable levels. The same degree of destruction is achieved in simi- larly contaminated foods when held at 140 F for 78 to 83 min.

Detailed Solution. The thermal death time of Salmonella typhi at 60ºC is 4.3 minutes. Salmonella Typhi is bacteria that infect the intestinal tract and the blood.

All samples (Figures 1 to 5) at 60 and 65 ºC have the same decline graph that is estimated to be the death of S. aureus at 60 minutes. At 70 ºC, the death of S. aureus occurred at 50 minutes.

Growth of staphylococci and production of toxin are greatest at approximately 20–37 °C, but growth can occur between 8 and 48 °C. This toxin is heat stable, being tolerant to boiling for 1 h. Canning under pressure at 121 °C for 30 min is sufficient to destroy the toxin.

S. aureus can grow at a temperature range between 15° to 45°C and at NaCl concentrations up to 15%. However, extended exposures above 42°C or below 10°C are not recommended.

Temperature may affect the transmission of Salmonella infections via several causal pathways, such as direct effects on bacterial proliferation and indirect effects on eating habits during hot days. The optimum temperature for the growth of Salmonellae is between 35°C and 37°C. The growth is greatly reduced at <15°C.

Thermal death time is how long it takes to kill a specific bacterium at a specific temperature. It was originally developed for food canning and has found applications in cosmetics, producing salmonella-free feeds for animals (e.g. poultry) and pharmaceuticals.

Exposure times greater than 12 hours at temperatures between 50°F (10°C) and 70°F (21.1°C) could result in toxin formation. Exposure times greater than 3 hours at temperatures above 70°F (21.1°C) could also result in toxin formation.

Samples stored at −70°C had almost no decay over time while S. aureus at 37°C had the lowest survival rates.

It is the time in minutes at a given temperature required to destroy 1 log cycle (90%) of the target microorganism. (Of course, in an actual process, all others that are less heat tolerant are destroyed to a greater extent).

What temperature kills Salmonella? ›

Cook: Cook your food to a temperature ranging between 145 and 165 degrees F to kill bacteria, including Salmonella. The CDC advises against cooking or storing food in the danger zone between 40 degrees F and 140 degrees F, which will cause bacteria to multiply.

The incubation period for Salmonella gastroenteritis (food poisoning) depends on the dose of bacteria. Symptoms usually begin 6 to 48 hours after ingestion of contaminated food or water and usually take the form of nausea, vomiting, diarrhea, and abdominal pain.

Bacteria multiply rapidly between 40 and 140 degrees. Bacteria will not multiply but may start to die between 140 and 165 degrees. Bacteria will die at temperatures above 212 degrees.

Furthermore, present research indicate that 62o C for 12.5 minute in Staphylococcus aureus and 7.5 minute in Staphylococcus epidermidis is sufficient to complete destruction of microorganism in distilled water.

PHYSICAL INACTIVATION: Staphylococcus aureus can grow in a pH of 4.2 to 9.3 and in salt concentrations of up to 15% ⁴. Enterotoxins are resistant to temperatures that would destroy the bacilli ⁴. Sensitive to dry heat treatment of 160-170 ^oC for at least an hour, but not to moist heat treatment ²⁴.

Cooking the food will kill the bacteria, but not the toxin if it has already spread in the food. So, the foods most at risk for staph are ones that were not kept in the refrigerator before cooking, or they're things that are not normally cooked. These include: Salads (tuna, macaroni, potato, and others)

Depending on the type of food, the Centers for Disease Control and Prevention recommend cooking food to a temperature between 145 degrees F and 165 degrees F to kill Salmonella.

The "Danger Zone" (40 °F-140 °F)

This range of temperatures is often called the "Danger Zone." That's why the Meat and Poultry Hotline advises consumers to never leave food out of refrigeration over 2 hours. If the temperature is above 90 °F, food should not be left out more than 1 hour.

Heat treatment at 64°C killed almost all E. coli cells in 1.5s, but the thermal death was not associated with disintegration of the cell envelope (Figs 1 ²3).