Food-Borne Pathogens: Salmonella

Introduction

Having covered E. Coli and C. Botulinum in previous entries, we now move on to covering Salmonella. This pathogen is most well-known for infecting raw chicken, but can be found in beef, turkey, and other products as well.

The Danger

According to the CDC, most persons infected with Salmonella experience diarrhea, fevers, and cramping between 12 and 72 hours after infection. This will last 4 to 7 days, with recovery not requiring specialized treatment.

Persons with compromised immune systems may experience more severe symptoms. Complications from Salmonella can result in death in some cases, with the CDC estimating 450 deaths from Salmonella per year in the United States. (Salmonella)

Control Metrics

Conditions for Growth (Lake, R., & Whyte, R.)
Temperature:
 Minimum temp: 7°C, Maximum: 49.5°C, Optimum: 35-37°C
pH:
 Minimum: 3.8, Maximum: 9.5, Optimum: 7-7.5
Atmosphere:
Can grow with or without oxygen
Water Activity:
Minimum: 0.94
Other Preservatives
: Salmonella is less resistant to acid, compared to E. Coli.

Inactivation
Temperature:
Freezing can kill Salmonella, but isn't considered a guaranteed method. Temperatures above 70°C can reduce the amount of Salmonella present by 90% per minute.
pH:
 The effect of pH on inactivation is dependent of the type of acid, and temperature. (See "Other Preservatives" below)
Water Activity:
 Water activities just below optimum
Other Preservatives:
 Acetic acid is of notable potency as a growth inhibitor for Salmonella, being effective at a concentration of 0.1% (pH 5.1) 

Pathogen Control in Preserved Foods

Because of its particularly strong effect on Salmonella, the use of vinegar would be a good way to help control the levels of Salmonella in a preserved food. Keeping meats and vegetables has been utilized for centuries, and continues to be used to this day.

A lacto-fermented good would also be a safer choice, as lactic acid is well-known for its anti-microbial action. Lactic acid is also known for being potent against other pathogens as well.

Salting, while commonly used, isn't a surefire way to prevent Salmonella contamination, but rather, it should be used to supplement other methods by keeping the water activity at a suitable level.

If Salmonella is still a concern, cooking a preserved meat can be a final step to ensure safety. Many medieval recipes call for salted meats to be boiled in a pot of wine or vinegar (sometimes mixed with some water). This will also introduce more acid as well.

Works Cited

Lake, R., & Whyte, R. (2002, August). RISK PROFILE: SHIGA TOXIN-PRODUCING ESCHERICHIA COLI IN RED MEAT AND MEAT PRODUCTS. Retrieved January 18, 2019, from https://www.foodsafety.govt.nz/elibrary/industry/Risk_Profile_Salmonella-Science_Research.pdf

Salmonella. (2018, March 05). Retrieved January 18, 2019, from https://www.cdc.gov/salmonella/general/index.html

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