WHY DO FOODS SPOIL?

And how can you prevent it§?

Food Spoilage vs. Foodborne Illness Food spoilage is any

change in food that causes it to be less desirable. E.g. brown bananas; not

necessarily “bad” but not too appetizing

As the chemicals in food change, a change in the smell, appearance, texture, or taste may occur

Food spoilage indicates that conditions may be favorable for growth of microorganisms

Foodborne illness is any illness that is derived from food.

Most foodborne illness are caused by microorganisms

Why does food spoil?

Food spoilage is caused by the activity of: Microorganisms Enzymes Chemicals

Microorganisms Include fungi and

bacteria Enzymes

Molecules that speed up or slow down chemicals reactions

Chemicals Harmful chemicals

may result from the activity of microorganisms or enzymes

Escherichia coli

Escherichia coli (abbreviated as E. coli) are a large and diverse group of bacteria.

Most forms of E. coli are harmless but some can cause diarrhea, while others cause urinary tract infections, respiratory illness and pneumonia, and other illnesses.

The most severe illnesses are caused by “shiga toxin producing” E. coli. These illnesses are spread through ingestion of tiny particles of feces (EWWWWW!!!!) Unfortunately, this happens more often then we would like to think.

Clostridium Botulinum Botulism is a rare but serious

paralytic illness caused by a nerve toxin that is produced by the bacterium Clostridium botulinum. 

Foodborne botulism is a severe type of food poisoning caused by the ingestion of foods containing the potent neurotoxin formed during growth of the organism.  The incidence of the disease is low, but the disease is of considerable concern because of its high mortality rate if not treated immediately and properly. 

Classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Eventually, paralysis of the extremities and chest muscles leading to death..

Campylobacter jejuni

Campylobacter jejuni is now recognized as one of the main causes of bacterial foodborne disease in many developed countries.

Most people who become ill with campylobacteriosis get diarrhea, cramping, abdominal pain, and fever within two to five days after exposure to the organism. The diarrhea may be bloody and can be accompanied by nausea and vomiting. The illness typically lasts one week. Some infected persons do not have any symptoms.

In persons with compromised immune systems, Campylobacter occasionally spreads to the bloodstream and causes a serious life-threatening infection.

Salmonella

Salmonella can survive for weeks outside a living body. They have been found in dried excrement after over 2.5 years.

Salmonella are usually transmitted to humans by eating foods contaminated with animal feces.(EWWWW!)

To protect against salmonella infection, it is recommended that food be heated for at least ten minutes at 75°C (165° F) (temperature at the center). The bacteria are not destroyed by freezing.

Vibrio Vulnificus

• V. vulnificus causes disease in individuals who eat contaminated seafood (usually raw or undercooked oysters) or have an open wound that is exposed to seawater. Among healthy people, ingestion of V. vulnificus can cause vomiting, diarrhea, and abdominal pain. 

• In immunocompromised persons, V. vulnificus can invade the bloodstream from either a wound or from the GI tract, causing a severe and life-threatening illness called primary septicemia, characterized by fever, chills, septic shock and death. V. vulnificus bloodstream infections are fatal about 50% of the time.

• There was V. vulnificus outbreak in New Orleans after Hurricane Katrina.

Aflotoxin

Growth of the fungus on a food source often leads to contamination with aflatoxin, a toxic and carcinogenic compound. Aspergillus flavus is also the second leading cause of aspergillosis in humans. Patients infected with A. flavus often have reduced or compromised immune systems.

Aflatoxin in dry dog food manufactured by Diamond Pet Foods was responsible for at least 23 dog deaths due to liver failure between Dec 2005 and early 2006

Almost all peanut products have an amount of aflotoxins but is it below the

Shellfish Toxins

Shellfish poisoning results from ingestion of shellfish contaminated with phycotoxins. These toxins are produced by micro-algae, upon which the shellfish feed.

Bivalve shellfish such as clams and oysters are common vehicles responsible for shellfish poisoning. This is because they are filter-feeders and naturally ingest the toxic algae in water. When the algae are toxin-producing, the toxins will be concentrated in the shellfish tissue. The amount of toxin in the shellfish depends on the number of toxic algae ingested.

The symptoms of shellfish poisoning range from gastrointestinal (nausea, diarrhea, cramping) to neurological (tingling, numbness, disorientation). The amount and type of toxin ingested determines the severity of the sickness.

Critical Factors

Factors that affect the growth or chemical reactions of disease causing microorganisms.

Temperature

Very high or very low temperature can kill or suppress the growth of microorganisms.

Chemical reactions are usually suppressed by low temperature

High temperatures denature proteins (enzymes)

Acidity (pH)

Acidity has to do with the chemical properties of a solution

Microorganisms prefer a neutral pH (around 7)

Anything that has a pH that is too low or too high will inhibit the growth of organisms and suppress chemical reactions.

Water

Water is needed for chemical reactions to occur in organisms

If no water is present, it inhibits the growth of molds and microorganisms

Oxygen

Organisms use oxygen in chemical reactions called oxidation reactions.

Do you remember what happens when metal oxidizes? This also occurs with food.

Oxidation produces chemicals that may make food more susceptible to microorganism activity. And it just doesn’t taste good