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Understanding Potentially Hazardous Foods: Proteins, Carbohydrates, Water, and Acidity, Study notes of Bacteriology

Florida Career CollegeBacteriology

The concept of potentially hazardous foods, which are capable of supporting the rapid growth of infectious and toxin-producing microorganisms. The article discusses the role of protein and carbohydrate content, moisture content, and acidity in the growth of bacteria. Examples of potentially hazardous foods are provided, along with information on water activity and temperature requirements for bacterial growth.

What you will learn

  • What are potentially hazardous foods?
  • What nutrients do bacteria need for growth?
  • How does water activity affect bacterial growth in food?

Typology: Study notes

2021/2022

Uploaded on 09/12/2022

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sheela_98 🇺🇸

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A potentially hazardous food is a food that is
natural or man made and is in a form capable
of supporting the rapid and progressive
growth of infectious and toxin-producing
microorganisms.
These foods typically have:
¾High protein or carbohydrate content
¾High moisture content
¾Low acidity
PROTEIN AND CARBOHYDRATE
Protein is a nutrient necessary for a variety of
processes in the human body. Like humans,
bacteria need protein to grow and multiply.
Meat, poultry, fish, seafood, eggs, beans, peas,
nuts and dairy foods have a high protein
content.
Carbohydrate is a nutrient primarily responsible
for providing energy to all cells of the body.
Bacteria also need carbohydrate for energy.
Bread and other grain foods, dairy foods, fruits
and vegetables can have a high carbohydrate
content.
WATER
Bacteria need a percentage of moisture or
“water by volume” in a food for growth. There
must be enough available water to support
growth. This is expressed as water activity (a
measure of water bound to food that is not
available for bacteria growth). Water activity
is measured on a scale from 0-1.0. Disease
causing bacteria grown in foods that have a
water activity higher than .85.
ACIDITY
The acidity of foods is expressed as pH. The pH
of a food is measured on a scale that ranges
from 0 to 14. Most foods considered “acidic”
have a pH less than 7.0. Foods with a pH less
than 4.6 do not normally support the growth of
disease-causing bacteria. Most bacteria prefer
a neutral environment near a pH of 7.0, but can
grow in a range of 4.6 to 9.0. Milk, meat and
fish are in this range.
Let’s Talk Science
POTENTIALLY HAZARDOUS
FOODS
Which food would have a lower water activity,
fresh chicken or frozen chicken? The answer is fresh
chicken with water activity at about .98. The water
activity of frozen chicken is zero. Even though
both are about 60% water by volume, the water
in the frozen chicken is not available to bacteria
for growth. Freezing slows
the growth of bacteria
to preserve food for long
periods.
What is a potentially hazardous food?
What Do You Think?
pf2

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Download Understanding Potentially Hazardous Foods: Proteins, Carbohydrates, Water, and Acidity and more Study notes Bacteriology in PDF only on Docsity!

A potentially hazardous food is a food that is natural or man made and is in a form capable of supporting the rapid and progressive growth of infectious and toxin-producing microorganisms. These foods typically have: ¾ High protein or carbohydrate content ¾ High moisture content ¾ Low acidity

PROTEIN AND CARBOHYDRATE

Protein is a nutrient necessary for a variety of processes in the human body. Like humans, bacteria need protein to grow and multiply. Meat, poultry, fish, seafood, eggs, beans, peas, nuts and dairy foods have a high protein content. Carbohydrate is a nutrient primarily responsible for providing energy to all cells of the body. Bacteria also need carbohydrate for energy. Bread and other grain foods, dairy foods, fruits and vegetables can have a high carbohydrate content.

WATER

Bacteria need a percentage of moisture or “water by volume” in a food for growth. There must be enough available water to support growth. This is expressed as water activity (a measure of water bound to food that is not available for bacteria growth). Water activity is measured on a scale from 0-1.0. Disease causing bacteria grown in foods that have a water activity higher than .85.

ACIDITY

The acidity of foods is expressed as pH. The pH of a food is measured on a scale that ranges from 0 to 14. Most foods considered “acidic” have a pH less than 7.0. Foods with a pH less than 4.6 do not normally support the growth of disease-causing bacteria. Most bacteria prefer a neutral environment near a pH of 7.0, but can grow in a range of 4.6 to 9.0. Milk, meat and fish are in this range.

Let’s Talk Science

POTENTIALLY HAZARDOUS

FOODS

Which food would have a lower water activity,

fresh chicken or frozen chicken? The answer is fresh

chicken with water activity at about .98. The water

activity of frozen chicken is zero. Even though

both are about 60% water by volume, the water

in the frozen chicken is not available to bacteria

for growth. Freezing slows

the growth of bacteria

to preserve food for long

periods.

What is a potentially hazardous food?

What Do You Think?

Many bacteria grow in a temperature range between 40 and 140^0 F. Under ideal conditions, bacterial cells can double in number every 15 to 30 minutes. Some double more quickly. Bacteria are single-celled microorganims that reproduce by binary fission. In this process, the cell divides into two identical daughter cells with identical DNA to the parent cell. Each daughter cell divides into two more cells. Over the course of just 7 hours, it is possible that one bacterium, such as Escherichia coli, could generate over two million bacteria! Exactly how many can make you sick depends on the kind of bacteria. For some, it only takes a few cells to cause foodborne illness. Examples of Potentially Hazardous Foods Time and Temperature

Meats

Poultry

Eggs

Fish

Shellfish

Dairy products

Cooked vegetables

Cooked rice

Cooked pasta

Cooked cereal

Cooked beans, peas and

lentils

Cut fruits and vegetables

Raw seed sprouts

Cooked soybean products

(such as Tofu)

Garlic-in oil or other

vegetable-in-oil mixtures

(unless they have been

treated to prevent

growth of Clostridium

botulinum )

The term “potentially hazardous foods” is used by the Food and Drug Adminsitration in the FDA Food Code. The Food Code is a model law that helps government entities, such as health departments, regulate retail and food service industries to protect the health of consumers. The principles of time and temperature also apply to foods you handle at home. It is important that you do not leave potentially hazardous foods at room temperature for more than two hours, or no more than one hour if the temperature is above 90^0 F. Keep Hot Foods Hot and Cold Foods Cold Prepared by: Janie Burney, PhD, RD, Professor, Family and Consumer Sciences