Glossary of Terms

Michigan State University Extension
Preserving Food Safely - 01600901

Glossary of Terms

ACID FOODS -                                                

     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.                                           

ALTITUDE -                                                  

     The vertical elevation of a location above sea level.  

ASCORBIC ACID -                                             

     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        

BACTERIA -                                                  

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

BLANCHER -                                                  

     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         

BOILING-WATER CANNER -                                      

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

BOTULISM -                                                  

     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.                         

CANNING -                                                   

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

CANNING SALT -                                              

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

CITRIC ACID -                                               

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

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.         

COLD PACK -                                                 

     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.                            

ENZYMES -                                                   

     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.                                       

EXHAUSTING -                                                

     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  

FERMENTATION -                                              

     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.  

HEADSPACE -                                                 

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

HEAT PROCESSING -                                           

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

HERMETIC SEAL -                                             

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

HOT PACK -                                                  

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

LOW-ACID FOODS -                                            

     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.         

MICROORGANISMS -                                            

     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.                          

MOLD -                                                      

     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.              

MYCOTOXINS -                                                

     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.             

PASTEURIZATION -                                            

     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.                                 

PICKLING -                                                  

     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.                                              

PRESSURE CANNER -                                           

     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         

RAW PACK -                                                  

     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.                                              

SPICE BAG -                                                 

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

STYLE OR PACK -                                             

     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.                

VACUUM -                                                    

     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.  

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