1. FOOD PRESERVATION: CANNING BASICS

2. Preserving Food Main home food preservation methods Canning Freezing
Drying
Choice of method depends upon
Safe guidelines
Product characteristics
To maintain safety and quality
Microorganisms
Enzymes
CHOICE OF METHOD DEPENDS UPON:
1. Safe guidelines for particular food item: If there are no canning recommendations for a particular food item, another option is to freeze
2. Product characteristics: Basil has a lot of water and does not freeze well, another option is to dry
THE PURPOSE OF PRESERVATION IS TO MAINTAIN SAFETY AND QUALITY OF FOOD.
To prevent spoilage, caused by microorganisms (mold, yeast, and bacteria).
Molds – some produce toxins; discuss mold shoots spreading into food, dispersion of toxins, and relationship to moisture content. Molds eat the natural acid present in the food, therefore causing a decrease in acidity (increase in pH). In home canned products, this could mean that the high acid products could become low acid and support the risk of botulism or other bacterial spoilage.
Yeasts – cause fermentation or spoilage by consuming organic compounds in food. Sometime you want fermentation, such as when making sauerkraut or when pickling by fermentation, sometimes you do not want fermentation (i.e. in applesauce). When pickling by fermentation, yeasts and microoganisms breakdown the carbohydrates, thereby increasing acidity (decreasing pH).
Bacteria –some cause spoilage, some produce toxins, and some are pathogens that cause foodborne illness.
To stop enzymatic activity. Enzymes are naturally present in food and their activity can lead to deterioration of food quality. Enzymes promote chemical reactions, such as ripening. These reactions will continue in food after harvest.

3. How Preservation Methods Work
Freezing reduces the temperature
Drying removes moisture
Canning applies heat
FREEZING: (1) Stops the growth of microorganisms; it does not sterilize foods or destroy the spoilage causing organisms. A few organisms may die, but once thawed to a warmer temperature these organisms can quickly multiply. (2) Chemical changes affect the quality in frozen foods. One major chemical reaction is oxidation. (3) Enzymes are naturally present in foods and their activity can lead to the deterioration of food quality. Enzymes promote chemical reactions, such as ripening. Freezing only slows the enzyme activity that takes place in foods. It does not stop these reactions which continue after harvest.
DRYING: Removes moisture from the food so bacteria, yeast, and mold cannot grow and spoil the food. Drying also slows down the action of enzymes, but does not inactivate them.
CANNING: is the process in which foods are placed in cans and heated to a temperature that destroys microorganisms and inactivates enzymes.

4. Principles of Canning
Heat processing at specified temperature for a specified time
Destroy organisms
Inactivate enzymes
Oxygen driven out
A Vacuum is formed upon cooling
Prevent recontamination

5. Home Canning Basics Recommend research-based recipes: USDA
Land grant universities
Ball® Blue Book (dated 1989 or later)
Time, temperature, product volume scientifically tested
If recipe not followed correctly
Poor quality product
Food poisoning
Death
Canned food is only as good as the fresh product you start with. When canning, select high quality, unblemished foods and prepare them by following tested directions from reputable sources such as USDA, your state’s Cooperative Extension Service, So Easy To Preserve or the Ball Blue Book of Canning, Freezing and Dehydration. It is very important to follow directions exactly. In canning, food is placed in a canning or Mason-type jar, not just any jar. These have been made to specifically stand up to the heat processes used in canning and can be used over and over without breaking. The jars are sealed using a 2-piece lid system which consists of a flat lid and a ring band. The jars are heated to a temperature that destroys microorganisms in the food. The heat also inactivates enzymes. Enzymes are natural chemicals in the food that can cause changes in color, flavor and texture of the product over time. During the heat processing, air is driven from the jar. As the jar cools, a vacuum seal is formed. This combination of events preserves the food. 5 5

6. Two Approved Methods of Canning Foods At Home
Boiling Water Bath (212°F)
Acidic foods (pH ≤ 4.6)
Addition of acidic ingredients
Pressure Canning (240°F)
Low-acid foods (pH ≥ 4.6)
Mixtures of acid and low-acid foods
There are two approved methods for canning foods at home. These are:
Boiling water canning: Boiling water canning is used for canning acid foods. At sea level, water boils at 212°F. As altitude increases, water boils at lower temperatures. Since lower temperatures would be less effective in killing bacteria, processing time would have to be increased as altitude increases.
Pressure canning: Pressure canning is only safe method for canning low acid canned foods. When canned under pressure, temperatures higher than the boiling point of water can be reached. These higher temperatures like 240°F are necessary to destroy spores of bacteria that cause botulism, a very deadly type of food poisoning, as well as spores of bacteria that cause spoilage. 6

7. pH = Acidity Acidity measurement = pH scale 0 – 14
Low pH values = high acidity
Different bacteria, different acid tolerance
Bacteria grow between pH 4.6 and 9.0
Bacteria thrive between pH 6.0 and 7.5
Vinegar
The term, “pH,” is a measurement of the acid level in a food. pH is measured on a scale from 1 to 14. The closer the pH value is to one, the more acid the food contains. A pH of 7 is neutral. 7 7 7

8. Can be safely heat processed in boiling water
Acidic Foods
pH < 4.6
Fruits
Tomatoes, figs, pears are borderline – require acidification
Fermented foods (sauerkraut, pickles) – yeasts breakdown carbohydrates, ↑ acidity
“Acid” foods have a pH less than or equal to Acid foods include most all fruits. However, tomatoes, figs and Asian pears are borderline and specific amounts of bottled lemon juice or citric acid must be added to them before canning to ensure safety of the recommended process. Acid foods also include sauerkraut and naturally fermented foods that are preserved by natural acids produced during the fermentation process and foods to which large amounts of acid (usually in the form of vinegar) are added. An example would be pickles.
PICKLING: the product has increased acidity to make it difficult for microbial growth.
Brined or fermented pickles go through a curing process in a salt water brine. If the product is fermented, lactic acid produced during the fermentation process helps preserve the product. In brined products that are cured, but not fermented, vinegar is added to help preserve the product. Use commercially bottled vinegars (5% acidity). Do not use homemade vinegar or vinegar of unknown acidity. Do not alter salt concentration in fermented pickles or sauerkraut. Proper fermentation depends on correct proportions of salt and other ingredients.
Quick process pickles are covered with boiling hot vinegar, spices, and seasonings. Sometimes the product is brined for several hours.
Fruit pickles are prepared from whole or sliced fruits and simmered in a spicy, sweet-sour syrup made of vinegar or lemon juice.
Relishes are made from chopped fruits and vegetables cooked to desired consistency in a spicy vinegar solution.
JAMS AND JELLIES: added sugar binds water making it difficult for microbial growth. Pectin combines with the added sugar and natural or added acid to form a gel. Pectin is highest in just ripe fruits and decreases as fruit becomes fully ripe. Commercial pectins are available in both powdered and liquid forms (they are not interchangeable in recipes). Special pectins are available to use for making jellied products with no added sugar or with less sugar than regular recipes. Do not get good gels at pH <4.6.
1. Jellies are made by cooking fruit juice with sugar
2. Jams are made by cooking crushed or chopped fruits with sugar.
3. Preserves are small, whole fruits or uniformly sized pieces in a thick slightly gelled sugar syrup.
4. Conserves are made by combining fruits with a consistency like jam.
5. Marmalades are soft fruit jellies containing small pieces or slices of fruit or fruit peel suspended in the jelly. They usually include citrus.
6. Fruit butters are made by cooking fruit pulp with sugar to a thick, spreadable consistency. Spices are often added.
7. Honeys and syrups are made by cooking fruit juice or pulp with sugar until thickened. Product is pourable.
Can be safely heat processed in boiling water 8 8

9. Must be heat processed in a pressure canner
Low-Acid Foods
pH > 4.6
Vegetables
Meats, poultry, seafood
Soups, stews
Mixtures of acid and low acid foods (spaghetti sauce – meat, vegetables and tomatoes)
Foods are considered to be low acid foods if they have a pH greater than This category includes vegetables, meats, poultry, seafood, soups and other mixtures of both acid and low acid ingredients. An example of such a mixture would be spaghetti sauce with tomatoes, meat and vegetables.
Must be heat processed in a pressure canner 9 9

10. Acidity measurement = pH scale 0 – 14
Low pH values = high acidity
Different bacteria, different acid tolerance; Bacteria grow between pH 4.6 and 9.0; Bacteria thrive between pH 6.0 and 7.5
Pathogens: pH
Yeasts: pH < 5.0
Molds: neutral pH, but tolerate acidic 10

11. Clostridium botulinum
Why Two Methods?
Clostridium botulinum
Commonly found in soil and marine sediment
Two forms
Vegetative cells
Spore
Vegetative cells killed at 212oF
Spores destroyed at 240oF
If do not destroy spores, they will germinate into vegetative cells when conditions become favorable and produce toxin
C. Botulinum spores are extremely common in soil and marine sediment, and therefore commonly found on the surfaces of fruits, vegetables, and seafood. The spore stage is formed when the bacteria are in an unfavorable environment; it is a protective stage that keeps the cell dormant but allows it to survive. When conditions become favorable, spores germinate into vegetative cells. Active vegetative cells are able to colonize and produce the deadly botulinum toxin. 11

12. Botulism Poisoning Favorable conditions for C. botulinum grothw:
Low oxygen
Low acidity (pH >4.6)
Moisture
Temperature
The botulinum toxin, one of deadliest known, causes botulism food poisoning.
C. Botulinum spores cannot germinate and then produce the toxin in pH levels of 4.6 or below.
Food can contain toxin without showing signs.
Symptoms usually appear within 12 to 72 hours:
Digestive upset (in some cases)
Blurred, double vision
Difficulty swallowing, speaking and breathing
Possible death from suffocation
10-35% mortality rate
Antitoxin is available, but there is slow recovery. Permanent nerve damage possible.
germinates
growth
(multiplies)
bacterium
spore
waste materials and toxins 12

13. Botulism Foodborne Illness
Symptoms appear within 12 to 72 hours:
Nausea, vomiting, weakness, dizziness
Blurred, double vision
Difficulty swallowing, speaking and breathing
Possible death from suffocation
When consumed by humans, the neurotoxin produced by vegetative cells binds to nerve endings that join muscles, preventing muscles from contracting. Symptoms begin with nausea, vomiting, weakness, and dizziness. Next are neurological symptoms such as blurry vision, difficulty speaking and swallowing, lack of muscle coordination. Eventually the diaphragm and chest muscles become affected, which prevents breathing and results in death from asphyxia. Quick medical attention and injection of the antitoxin can stop the illness, but rarely reverse nerve damage. Also, the antitoxin cannot always be used due to serious side effects. 13

14. Botulism Foodborne Illness
Potentially fatal
Permanent nerve damage
Food can contain toxin without showing signs of contamination
Improperly home canned vegetables remain the leading cause 14

15. Foodborne Botulism Outbreaks in US
116 reported outbreaks from a
75 (91%) caused by home-prepared foods
33 (44%) home-canned foods
Home canned vegetables significant causea
Preserving low acid food improperly
Modifying instructions
Low awareness of risk of botulism
a Journal of Food Protection, Vo. 74, No. 12, 2011, Pages

16. 16

17. Preventing Botulism Follow the recipe- NO MODIFICATIONS!
Several factors affect heat penetration
Jar
Food
Cold-spot
Slowest heating area of the jar
Determines process time
Use recommended canners
Heat-up and cool-down times in pressure canner are counted toward “sterilization”
DO NOT RUSH!!!
Several factors affect heat penetration
Jar: Shape and size of jar
Food:
Solid to liquid ratio
Protein, sugar, fat, added thickeners
Size, shape and texture of food pieces
Cold-spot
Slowest heating area of the jar
Determines process time
Each food has its own processing time
Use recommended canners: Heat-up and cool-down times in pressure canners are counted toward “sterilizing” the contents of the jar. Do not rush!!! 17

18.        
EQUIPMENT 18

19. Equipment - Jars and Lids
Don’t use if chipped
Keep hot
Processing <10 min. = must be sterilized
Lids
ALWAYS use new flat lids
Lid has a sealing compound filled channel
Keep hot until used
Threaded screw band 19

20. Vacuum Seal Heat-processed and cooled
Pressure outside of jar > inside jar
Pushes lid down
Sealing compound conforms to rim
Creates air tight seal
Prevents recontamination of the food
Failure to adequately heat-process
= seal failure, food spoilage, health risks
The vacuum seal is what keeps the lid on the jar during storage. It prevents the product from becoming recontaminated, and it keeps the food from drying out. 20

21. Packing Methods – Raw/Cold Pack
Raw, unheated food
Boiling liquid poured over the food
Tightly pack fruits and most vegetables because that will shrink during processing
Loosely pack starchy vegetables that will expand during processing
The method of packing the jars also plays an important role in heat transfer through the product. In a raw pack, raw food is placed directly in the jars. Then hot, boiling liquid is poured over the contents. Pack firmly, but do not crush. Free the bubbles or trapped air between the pieces of food. Obtain proper headspace. Wipe the jar rims. Add lids, adjust ring bands and process. 21

22. Packing Methods – Hot Pack
Put hot food and boiling liquid into jars
Pack fairly loosely because shrinking already occurred
Make sure enough cooking liquid covers the food
Preferred method for most foods
The preferred method of pack for most foods is the hot pack. In a hot pack, foods are cooked in liquid before packing. Then the cooking liquid is poured over the food in the jar. The advantages of this method are that fewer jars are needed, there is less floating of the food because air has cooked out of it, the color and flavor are better retained, and the foods are easier to pack in the jars because they are more pliable. Always follow directions for the specific type of pack called for.
[Activity: Have jars of food canned by hot pack method and same food canned using a raw pack. Ask the audience which method they think was used for each jar and why. Raw packs usually have more floating food than hot packs.]
Note: If directions say only hot pack then hot pack! 22

23. Headspace Empty space Allows food to expand
Allow for good vacuums to be formed
When filling the jars, it is important not to overfill. We call the space at the top of the jar, between the top of the food and the bottom of the lid, the headspace. Check the directions for the correct amount of headspace called for in a recipe. For jelly, it is usually ¼ inch. For acid foods like fruits, tomatoes and pickles, it is ½ inch. For low acid foods like vegetables, meats and mixtures of acid and low acid foods, it is usually one inch. 23

24. Headspace TOO LITTLE = PREVENT SEALING TOO MUCH = AIR IN JAR
= FOOD DISCOLOR
What happens if you do not leave the correct headspace?
If there is too little, food may bubble out or run over during processing. Then deposits on the rim may keep the jar from sealing properly. If there is too much headspace, the food at the top of the jar is likely to discolor during storage, and the jar may not seal because all of the air was not forced out. 24

25. Air Bubbles Rise during processing = Too much headspace
= Prevent sealing
To prevent air bubbles
Run a plastic or rubber knife-like
utensil around the edges of the jar
Gently shift the food
More liquid may need to be added to ensure proper headspace

26. Boiling Water Bath Canner
Water: 1-2 inches MUST cover the jars
Place ALL jars in canner
Start timer when water returns to a boil
Cover
DO NOT DISTURB jars for hours
For Boiling Water Bath:
Place rack in the canner. The rack allows the boiling water to circulate around the jars.
Fill the canner with enough water so that 1-2 inches of water covers the jars when they are placed in the canner. If less water covers the jars, will not get sterilization!
Place jars in canner, keep jars straight up , do not tilt.
Add more boiling water if needed to have 1-2 inches over the top of the jars
When the processing time has completed, turn off burner and remove lid
Leave jars in canner for 5 minutes
When it is time to remove the jars from the canner, careful not to tilt, place them on a thick clean towel, plastic/wooden cutting board, or cake rack to cool.
Do not sit the jars directly on a cool surface
DO NOT DISTURB jars for hours 26

27. Pressure Canning Water: 2-3 inches Place jars in canner
Heat the pressure canner until steam comes out of the vent tube
Allow steam to vent for 10 min.
Process times are for a pure steam environment
USDA instructs to vent ALL pressure canners
DO NOT DISTURB jars for hours
If pressure drops anytime during the process, bring the canner back up to required pressure and start timing the process over, from the beginning
Heat the pressure canner until steam comes out of the vent tube. As water boils, the “empty” space becomes a mixture of steam and air
Allow steam to vent for 10 min.to eliminate the air so processing takes place in a pure steam environment
Drop in pressure during processing
Decrease sterilizing value of the process
Under processing
Foodborne illness or spoilage
Large and/or quick variations in pressure may cause loss of liquid from jars
If pressure drops anytime during the process, bring the canner back up to required pressure and start timing the process over, from the beginning 27 27

28. Pressure Canners vs. Cookers
NOT INTERCHANGEABLE!
Canners MUST hold at least 4 quart-size jars
Cookers have less metal, smaller diameter, and use less water
= shorter processing time
= reduced heat
= under processed product
= risk of botulism!
National Center for Home Food Preservation
Preserving Food: Using Pressure Canners
Not interchangeable! Cannot convert processes intended for use with regular pressure canners to ensure safety when canning in other types of equipment.
A pressure canner pot MUST hold at least 4 quart-size jars to be considered a pressure canner for the USDA published processes
The time it takes the pressure cooker to come up to processing pressure and the time it takes the canner to cool down to 0 pounds of pressure at the end of the process will be less than for the standard pressure canner. This total time (to come up to pressure and cool down to 0 pressure) are part of the total processing heat used to establish USDA process times for safety. 28

29. Dial Gauge - Indicates pressure inside the canner
Must be checked for accuracy
Has dead- or counter-weight to close open vent for pressurizing
Pressure is increased or decreased by adjusting burner heat
Weighted Gauge - Weights regulate pressure inside the canner – 5, 10, 15 lb.
Open vent is where the weights fit
Steam, exhausted during processing, causes the weights to rock or jiggle
Does not require testing for accuracy, but replace the weights if they become damaged
How Does a Pressure Canner Work:
↑ pressure = ↑ boiling point of water = superheated water above the normal boiling point of water
Trapped steam increases the internal pressure and temperature
Steam circulates around the jars
Heat is transferred by conduction
Food in center of jar must reach 240°F
Discuss how much water to add to each type of canner
Discuss when to start timing the heat process
Discuss what to do when removing jars from canners – do not disturb for hours 29

30. Pressure Canners Features
Dial Gauge
Indicates pressure inside the canner
Must be checked for accuracy
Has dead- or counter-weight to close open vent for pressurizing
Adjust heat to maintain pressure 30 30

31. Pressure Canners Features
Weighted Gauge
Weights regulate pressure inside the canner – 5, 10, 15 lb.
Open vent is where the weights fit
Steam, exhausted during processing, causes the weights to rock or jiggle
Does not require testing for accuracy, but replace the weights if they become damaged 31 31

32. Storing Home Canned Food
Label and date
Store without ring bands
Store in cool, dark, dry place
Refrigerate unsealed jars
Avoid temperature extremes
For best quality, use within a year
If the jars are not sealed, you can reprocess the food if everything else was done correctly and if you catch it within 24 hours. You have to start over and basically go through the whole process as if you were starting from scratch and use a new lid. If you do not wish to reprocess, you can either refrigerate the food and use it quickly or you can freeze it for longer storage.
If the jars sealed properly, store the food in a cool, dry, dark place. Avoid storing them where they are near heat pipes or in areas where they will be exposed to temperature extremes.
For best quality, use home canned foods with one year. 32

33. Information Staff, Agricultural Research Service, USDA.
Disclaimer:
Trade and brand names are used only for information. The University of Rhode Island does not guarantee nor warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable.
Document Use:
Adapted with permission of the University of Georgia. Harrison, J.A Canning Foods at Home – The Basics (slides). Athens, GA: The University of Georgia, Cooperative Extension.
So Easy to Preserve, 5th Edition, 2006, University of Georgia Cooperative Extension Service
Adapted with permission of the University of Georgia. Andress, E.L Freezing fruits and vegetables at home (slides). Athens, GA: The University of Georgia, Cooperative Extension Service.
Adapted with permission of the University of Illinois. Finck, J Drying Foods (slides). Springfield, IL: The University of Illinois, Extension.
Ball® Complete Book of Home Preserving, Ed. J. Kingry and L. Devine, Robert Rose Inc.
Photography Credits
Elizabeth Andress and Elaine D’Sa, National Center for Home Food Preservation, University of Georgia.
Information Staff, Agricultural Research Service, USDA.
North Caroline State University 33