Food Safety and Meat - Meat Science

Objectives:

To introduce students to the major foodborne bacteria which impact the food safety of products, particularly meat products.
To familiarize students with the sources, implications, and control measures of various foodborne bacteria.

Escherichia coli/ E. coli O157:H7

Overview

Escherichia coli, or E. coli, are a group of bacteria normally found in the intestines of warm-blooded animals including some food animals and humans, and in water contaminated by animal and human feces.
When they cause illness due to contaminated food or water, E. coli are normally associated with intestinal complaints or diarrhea.
E. coli O157:H7 is a virulent strain of E. coli, a pathogen which can cause serious and potentially fatal diseases.

Sources

Like other strains of coli, E. coli O157:H7 can be transmitted through inadvertent contact with fecal matter during processing of animal foods or because of improper food handling.
Another common method of E. coli O157:H7 contamination is by infected food handlers who have not effectively washed their hands before touching food or food preparation utensils and surfaces.
E. coli O157:H7 has been identified in ground beef products, unpasteurized milk, and foods of plant origin.
Other outbreaks have been attributed to contaminated municipal and recreational water, and person-to-person transmission.

Symptoms/complications

Intestinal distress and diarrhea are symptoms of illness caused generic coli.
Symptoms of E. coli O157:H7 include severe abdominal cramps and watery diarrhea.
Hemorrhagic colitis, a complication of E. coli O157:H7 illness, causes severe abdominal cramps, bloody diarrhea, vomiting, and nausea, and possibly a low-grade fever.
Symptoms generally begin 3 to 9 days following infection and may last 2 to 9 days.
Approximately 2 to 7% of confirmed E. coli O157:H7 also develop hemolytic uremic syndrome (HUS).
HUS, characterized by severe anemia and renal (kidney) failure, is a leading cause of acute kidney failure in children.
Adults may develop HUS or thrombotic thrombocytopenic purpura (TTP), an illness similar to HUS but with involvement of the central nervous system, which can lead to strokes and seizures.

Salmonella

Overview

Salmonella bacteria are the most commonly reported cause of foodborne illness.
The bacteria cycle continuously through the environment via the intestinal tracts of animals and humans.
The illness caused by Salmonella is called salmonellosis.

Sources

Salmonella bacteria are most commonly found in raw or undercooked foods such as poultry, eggs, unpasteurized milk, or other dairy products and meats.
Fruits, vegetables, yeast, and chocolate also have been implicated in Salmonella
Because of cross-contamination, Salmonella can be present in almost any food product.

Symptoms/complications

Symptoms of salmonellosis include headache, abdominal pain, diarrhea, fever, and nausea.
Symptoms generally begin 8 to 48 hours after eating contaminated food and can last anywhere from 1 to 8 days.

Listeria monocytogenes

Overview

Listeria monocytogenes are foodborne bacteria that enter the intestines of warm-blooded animals including some food animals and humans following the ingestion of contaminated food.
Once inside the body, the bacteria multiply and eventually produce numbers sufficient to cause illness.
The illness caused by Listeria monocytogenes is called listeriosis.

Sources

Listeria monocytogenes bacteria are commonly found in the intestines of humans and animals, in milk, soil, leafy vegetables, and in food processing environments.
The bacteria also have been isolated in raw and cooked poultry, meat, seafood, salad, and sandwiches.
Unpasteurized dairy products, meat patés, and processed meats are frequent food carriers.
These bacteria can grow at refrigerated temperatures.

Symptoms/complications

In adults, symptoms include the sudden onset of fever, chills, headache, backache, and occasional abdominal pain and diarrhea.
Newborns can contract listeriosis from an infected mother during birth.
In newborns, symptoms include respiratory distress, refusal to drink, and vomiting.
Symptoms may begin from one day to several weeks following infection.
Listeriosis can cause spontaneous abortions and stillbirths.
Listeriosis is potentially fatal because of producing complications including septicemia (blood poisoning), meningitis, and meningo-encephalitis, which affects tissues around the brain or spine.

Campylobacter jejuni

Overview

Campylobacter jejuni is recognized as one of the leading causes of diarrhea in the United States.
The illness caused by Campylobacter jejuni is called campylobacteriosis.

Sources

Poultry, shellfish, livestock, and even pets carry the Campylobacter jejuni
Cases of campylobacteriosis have been attributed to undercooked poultry and meats, raw (unpasteurized) milk, and untreated water.

Symptoms/complications

Muscle pain, headache, and fever followed by diarrhea, abdominal pain, and nausea that begin 1 to 10 days following ingestion.
Convulsions may occur in some young children in association with high fever.

Clostridium perfringens

Overview

Clostridium perfringens bacteria are found in the intestines of humans and animals, in soil, dust, insects, and sewage.
The organism produces a toxin in the gastrointestinal tract, which causes the illness known as Clostridium perfringens

Sources

Known as the “cafeteria germ,” Clostridium perfringens outbreaks frequently occur when large quantities of food are served at room temperature or from a steam table.
Foods not cooled properly after serving also contribute to outbreaks.
Meat, poultry, cooked dried beans (refried beans), and gravies are the most common carriers of Clostridium perfringens.
Contamination from unwashed vegetables also is possible.

Symptoms/complications

Mild diarrhea and gas pains that begin between 6 and 24 hours after ingestion and lasts about 24 hours.
The illness is most serious for the elderly.

Staphylococcus aureus

Overview

Staphylococcus aureus multiply to a high level in foods left at room temperature, releasing an enterotoxin. As little as 2 hours at unrefrigerated temperatures may allow sufficient bacterial growth and toxin production to cause illness.
Staphylococcus aureus bacteria are heat-sensitive, but they produce a heat-stable enterotoxin, which causes illness. Reheating foods that already contain the toxin will not prevent illness.
Ingestion of Staphylococcus aureus enterotoxin can result in Staphylococcal food poisoning.

Sources

The most common source of Staphylococcus aureus is from humans, as the organism is harbored in nasal passages and on the skin.
Food handlers commonly contaminate foods that do not undergo adequate heating to kill the organism or adequate refrigeration to prevent the growth of the organism.
Outbreaks most frequently involve foods high in protein, such as pork, beef, and poultry. Foods such as potato and egg salads, poultry dressings, and gravies that are likely to be kept at room temperature for long periods of time also have been involved in outbreaks.
Occasionally cows with infected udders transmit the bacteria.

Symptoms/complications

Abrupt onset of severe nausea, abdominal cramps, vomiting, diarrhea, and low-grade fever.
Symptoms usually begin 1 to 6 hours after consumption of the contaminated food and usually last 1 to 2 days.

Food safety control measures – packers and processors

Beef, pork, and lamb slaughterers

Organic acid sprays (2 to 5% lactic acid, acetic acid, etc.)
Hot water rinses (≥180° F hot water)
Steam pasteurization

Beef, pork, and lamb wholesale fabrication/trim production

Lactic acid sprays
Peroxyacetic acid (PAA)

Fully cooked establishments

Appendix A, Lethality: USDA cooking guidelines (temperature and time) used to destroy heat-sensitive organisms such as Salmonella, coli O157:H7, Campylobacter jejuni
Appendix B, Stabilization: USDA chilling guidelines (temperature and time) used to prevent no log increase in Clostridium botulinum and no more than 1 log₁₀ increase in Clostridium perfringens.
Listeria control program that prevents occurrence of Listeria monocytogenes in the environment, both for contact and non-contact surfaces.
Antimicrobial compounds for processed meats such as sodium/potassium lactate, sodium diacetate, and sodium acetate.

Food safety control measures – food handlers and consumers

General

Never consume unpasteurized, raw, or undercooked foods of animal origin.

Cooking

Cook non-ground meat cuts (beef, pork, and lamb) to an internal temperature of at least 145°F (with a 3-minute rest) and poultry to 165°F.
Cook ground meats (beef, pork, veal, lamb) to a uniform temperature of at least 160°F, and ground poultry to 165°F.

Storage and Reheating

Keep hot foods hot (at or above 140°F) and cold foods cold (at or below 40°F).
Large leftover portions of cooked should be divided up for storage in shallow pans and cooled in the refrigerator.
Heat leftovers and ready-to-eat foods such as hot dogs to at least 160°F before serving.

Handling

Because Staphylococcus is a common bacteria, food handlers should not have not any boils, sores, or abscesses that could infect food or food preparation utensils and surfaces.
Carefully follow “keep refrigerated,” “sell by,” and “use by” dates, especially since Listeria monocytogenes grows at refrigeration temperatures.
Wash food preparation utensils and surfaces with warm, soapy water after each use.
Always wash hands thoroughly with warm, soapy water after going to the bathroom and before preparing or eating food.
Wash produce thoroughly before preparing, using only clean, drinkable water.
Thaw poultry and meat in the refrigerator or microwave oven and cook immediately after thawing.

Review of Material — What the student should know:

(1) General aspects of foodborne pathogens and their impact on the meat industry.

(2) Control measures important for food handlers and consumer and packers and processors.

Links to related sites

United States Department of Agriculture, Food Safety and Inspection Service

Center for Disease Control and Prevention

Author: J.W. Savell

Updated April 13, 2021