Michigan State University Extension
Preserving Food Safely - 01600901

Glossary of Terms


Foods which contain enough acid to result in a pH of
4.6 or lower. Includes all fruits except figs; most
tomatoes; fermented and pickled vegetables; relishes; and
jams, jellies and marmalades. Acid foods may be processed
in boiling water.


The vertical elevation of a location above sea level.


The chemical name for vitamin C. Lemon juice contains
large quantities of ascorbic acid and is commonly used to
prevent browning of peeled, light-colored fruits and


A large group of one-celled microorganisms widely
distributed in nature. See MICROORGANISM.


A 6- to 8-quart lidded pot designed with a fitted
perforated basket to hold food in boiling water, or with a
fitted rack to steam foods. Useful for loosening skins on
fruits to be peeled, or for heating foods to be hot


Large standard-sized lidded kettle with jar rack,
designed for heat-processing 7 quarts or 8 to 9 pints in
boiling water.


An illness caused by eating toxin produced by growth
of CLOSTRIDIUM BOTULINUM bacteria in moist, low-acid food,
containing less than 2 percent oxygen and stored between
40 degrees and 120 degrees Fahrenheit. Proper heat
processing destroys this bacterium in canned food. Freezer
temperatures inhibit its growth in frozen food. Low
moisture controls its growth in dried food. High oxygen
controls its growth in fresh foods.


A method of preserving food in air-tight
vacuum-containers and heat processing sufficiently to
enable storing the food at normal home temperatures.


Also called pickling salt. It is regular table salt
without the anti-caking or iodine additives.


A form of acid that can be added to canned foods. It
increases the acidity of low-acid foods and may improve
the flavor.


Vegetables, some tomatoes, figs, all meats, fish,
seafoods and some dairy foods are low acid. To control all
risks of botulism; jars of these foods must be (l) heat
processed in a pressure canner, or (2) acidified to a pH
of 4.6 or lower before processing in boiling water.


Canning procedure in which jars are filled with raw
food. "Raw pack" is the preferred term for describing this
practice. "Cold pack" is often used incorrectly to refer
to foods that are open-kettle canned or jars that are
heat-processed in boiling water.


Proteins in food which accelerate many flavor, color,
texture and nutritional changes, especially when food is
cut, sliced, crushed, bruised and exposed to air. Proper
blanching or hot packing practices destroy enzymes and
improve food quality.


Removal of air from within and around food and from
jars and canners. Blanching exhausts air from live food
tissues. Exhausting or venting of pressure canners is
necessary to prevent a risk of botulism in low-acid canned


Changes in food caused by intentional growth of
bacteria, yeast or mold. Native bacteria ferments natural
sugars to lactic acid, a major flavoring and preservative
in sauerkraut and in naturally fermented dills. Alcohol,
vinegar, and some dairy products are also fermented foods.


The unfilled space above food or liquid in jars.
Allows for food expansion as jars are heated, and for
forming vacuums as jars cool.


Treatment of jars with sufficient heat to enable
storing food at normal home temperatures.


An absolutely airtight container seal which prevents
reentry of air or microorganisms into packaged foods.


Heating of raw food in boiling water or steam and
filling it hot into jars.


Foods which contain very little acid and have a pH
above 4.6. The acidity in these foods is insufficient to
prevent the growth of the bacterium CLOSTRIDIUM BOTULINUM.

Vegetables, some tomatoes, figs, all meats, fish,
seafoods and some dairy foods are low acid. To control all
risks of botulism; jars of these foods must be (l) heat
processed in a pressure canner, or (2) acidified to a pH
of 4.6 or lower before processing in boiling water.


Independent organisms of microscopic size, including
bacteria, yeast and mold. When alive in a suitable
environment, they grow rapidly and may divide or reproduce
every 10 to 30 minutes. Therefore, they reach high
populations very quickly. Undesirable microorganisms
cause disease and food spoilage. Microorganisms are
sometimes intentionally added to ferment foods, make
antibiotics and for other reasons.


A fungus-type microorganism whose growth on food is
usually visible and colorful. Molds may grow on many
foods, including acid foods like jams and jellies and
canned fruits. Recommended heat processing and sealing
practices prevent their growth on these foods.


Toxins produced by the growth of some molds on foods.


Food is supposedly adequately heat processed in a
covered kettle, and then filled hot and sealed in sterile
jars. Foods canned this way have low vacuums or too much
air which permits rapid loss of quality in foods.
Moreover, these foods often spoil because they become
recontaminated while the jars are being filled.


Heating of a specific food enough to destroy the most
heat-resistant pathogenic or disease-causing microorganism
known to be associated with that food.

pH -

A measure of acidity or alkalinity. Values range from
0 to l4. A food is neutral when its pH is 7.0: lower
values are increasingly more acid; higher values are
increasingly more alkaline.


The practice of adding enough vinegar or lemon juice
to a low-acid food to lower its pH to 4.6 or lower.
Properly pickled foods may be safely heat processed in
boiling water.


A specifically designed metal kettle with a lockable
lid used for heat processing low-acid food. These canners
have jar racks, one or more safety devices, systems for
exhausting air, and a way to measure or control pressure.

Canners with 20-21 quart capacity are common. The
typical volume of canner that can be used is 16 quart
capacity, which will contain 7 quart jars. Use of pressure
saucepans with less than 16 quart capacities IS NOT


The practice of filling jars with raw, unheated
food. Acceptable for canning low-acid foods, but allows
more rapid quality losses in acid foods heat processed in
boiling water.


A closeable fabric bag used to extract spice flavors
in pickling solution.


Form of canned food, such as whole, sliced, piece,
juice or sauce. The term may also be used to reveal
whether food is filled raw or hot into jars.


The state of negative pressure. Reflects how
thoroughly air is removed from within a jar of processed
food--the higher the vacuum, the less air left in the jar.

A group of microorganisms which reproduce by
budding. They are used in fermenting some foods and in
leavening breads.
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