Transcript Salt as a Food Preservative

Unit
Food Science
Problem Area
Processing Animal Products
Lesson
Salt as a Food Preservative
Student Learning Objectives
1. Describe the uses of salt as a food
preservative and explain why salt is an
effective food preservative.
2. Discuss the relationship between
moisture content in meat products and
microbial activity.
Terms
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Aerobic
Bacteria
Condensation
Dehydration
Food spoilage
Mold
Plasmolysis
Proteolytic enzyme
Spores
Terminal treatment
Yeast
What are the uses of salt as a food preservative and why
is salt an
effective food preservative?
 A. Chemical preservatives, such as salt, are
used when terminal treatment (thermal
processing, freezing, drying, fermentation, or
refrigeration) is not a suitable preservation
method. Chemical preservatives are also used
to reduce the intensity (amount needed) of a
terminal treatment.
 B. Salt enhances flavor and improves keeping quality. Salt inhibits
microbial growth by causing dehydration, removal of water from a
molecule by the action of heat or a dehydrating agent. Most
microbes and bacteria require moisture to survive. Salt also
preserves food by:
 1. Reducing water available to microorganisms.
 2. Increasing osmotic pressure created in the aqueous
environment surrounding the microbial cell. The increase in
osmotic pressure causes plasmolysis, a partial
dehydration where the protoplast of a cell shrinks away from
the wall following water loss due to exposure of a solution of
higher osmotic pressure.
 3. Reducing the solubility of oxygen in water.
 4. Sensitizing cells to carbon dioxide.
 5. Interfering with the action of proteolytic enzymes,
enzymes that catalyze the breakdown of proteins into
simpler substances.
What is the relationship between moisture content in
meat products and microbial activity?
 Moisture content in meat products has a direct
relationship to microbial activity.
 A. Food deterioration is a broad term that
includes reduction in nutritional safety or
aesthetic appeal. Food spoilage is the
deterioration of a food product due to
microorganisms, enzymes, environment (heat
and cold), light and other radiation, oxygen,
moisture (or lack of it), industrial contaminants,
macroorganisms, and time.
 B. Microorganisms such as bacteria, yeast, and
molds, that are on or in food products are frequently
a major cause of food spoilage. Bacteria are
microscopic, relatively simple microorganisms that
have a primitive nucleus. Yeast is a collective name
for those fungi which possess a vegetative body
(thallus) consisting of simple individual cells.
 Mold is any type of various wooly fungus growths.
Microorganisms are found in the soil, water, air, and
on the exterior of nearly everything that is not
sterilized. Microorganisms are usually not found
within living tissue.
 C. Bacterial spores, an asexual, reproductive body
that is resistant to unfavorable environ-mental
conditions and produces a new vegetative individual
when the environment is favorable, are far more
resistant to adverse conditions and most processing
methods than mold or yeast spores. Sterilization
methods are aimed at these highly resistant
bacterial spores.
 D. When food is contaminated, several types of
microorganisms are present together to produce
acid, gas, putrification, or discoloration. Putrid odors
are produced when microorganisms digest proteins.
 E. Bacteria, yeasts, and molds prefer warm,
moist conditions. Some bacteria and all molds
require oxygen for growth and survival, a
condition known as aerobic. Most foodassociated bacteria multiply best at
temperatures between 16 and 38 degrees C.
 The slightest amount of condensation, liquid
forming from a vapor, on the surface of food can
become a hot spot for the rapid multiplication of
bacteria or growth of mold. Moisture trapped in
packaging containers supports the growth of
microorganisms.
Review/Summary
What are the uses of salt as a food
preservative and why is salt an effective
food preservative?
What is the relationship between moisture
content in meat products and microbial
activity?