Transcript Canning - University of Rhode Island

HOME CANNING
THE BASICS
MARTHA SMITH PATNOAD, CP-FS
CE FOOD SAFETY EDUCATION SPECIALIST
DEPT OF NUTRITION AND FOOD SCIENCES
UNIVERSITY OF RHODE ISLAND
401-874-2960
[email protected]
8/10
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Two Approved Methods of
Canning Foods At Home
1)
Boiling Water Canning (212°F)
Acid foods, ie- tomatoes, pickles,
relishes, salsas, jams and jellies
2)
Pressure Canning (at least
240°F)
• Low acid foods
• Mixtures of acid and low acid
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foods )
Why Two Methods?

Depends upon the food item

Acid vs Low Acid
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Why Two Methods?
Clostridium botulinum

Yeasts, molds and most bacteria are
destroyed at boiling temperatures
(212oF).

C. botulinum forms spores that require
higher temperatures for destruction in
a reasonable period of time
(usually 240oF).
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Botulism Foodborne Illness

The botulinum toxin, one of deadliest
known, causes botulism food
poisoning.

1 mg can kill 655 tons of mice.

Food can contain toxin without
showing signs.

Antitoxin is available, but there is
slow recovery. Permanent nerve
damage is possible.
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Botulism Foodborne Illness

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

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Botulism Poisoning

To germinate and produce toxin, the
spores need the following conditions:
 Anaerobic ( no air)
 Low acid (pH > 4.6)
 40oF to 120oF
 Relatively high moisture
spore
(germinates)
bacterium
growth
(multiplies)
waste materials and toxins
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Preventing Botulism
 Home
Canned Foods
Spores won’t germinate in acid foods
(pH < 4.6).
 Spores are killed when heated long
enough at a specific temperature.
 USDA usually recommends 240oF
canned low-acid foods.
 Pressure canner MUST be used for
all low-acid foods.

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Preventing Botulism, cont.
 Food
must be properly prepared
and processed for the correct time
 Pressure canner accurate and
operated correctly
 Foods checked when opening jars
 Foods should be boiled for at least
10 minutes before serving
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Preventing Botulism, cont.

Follow the recipe- NO MODIFICATIONS
The following slow down heat penetration:
 Extra sugar or fat
 Oversize food pieces
 Added thickeners

Use recommended canners
Heat-up and cool-down times in pressure
canners are counted toward “sterilizing” the
contents of the jar. Don’t rush!!!
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HOME CANNING :
THE PROCESSES
Home Canning Basics
FOODS CAN BE DIVIDED INTO TWO
CATOGORIES:
1. ACID
2. LOW ACID
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Acid Foods

Generally all fruits

Tomatoes (specific
amounts of citric acid or
bottled lemon juice are
added to acidify)

Sauerkraut

Foods to which large
amounts of acid are
added (pickles,
relishes, salsas)
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Low Acid Foods
Generally all vegetables
 Meats
 Poultry
 Seafood
 Soups
 Mixtures of acid and low acid foods
(spaghetti sauce – meat, vegetables and
tomatoes)

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Acidity
Acidity measurement = pH
 Low pH values = high amount
of acidity
 Bacteria can grow between
pH 4.6 and pH 9.0
 Bacteria grows best
between pH 6.0 and
pH 7.5

Vinegar
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Acidity
Alkaline
Acid
0 1.0 2.0 3.0
14.0
4.0
4.6
Commercial Orange
Mayonnaise Juice
Apples
Limes
Pickles
Vinegar
5.0 6.0 6.4
7.0
Distilled
Water
Chicken
Beef, Milk
Veal Corn
Pork
Carrots,
Pumpkins
Sweet Potatoes
Cheddar Cheese
8.0
8.5 9.0
10.0
11.0
12.0
13.0
Egg White
Soda
Crackers
 Acidity levels affect
bacterial growth
 Different bacteria,
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different acid tolerance
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Home Canning Basics
•
Use only recipes/directions and DO NOT
MODIFY from: USDA/ Cooperative Extension,
National Center for Home Food Preservation
(www.homefoodpreservation.com), Ball Blue
Book, So Easy To Preserve.
•
Always use current methods and information.
NEVER USE “granny’s method.”
•
Use only high/ quality food/ fresh produce.
•
Food must be properly prepared and processed
the correct amount of time.
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Home Canning Basics
•
Food is placed in a canning jar with a 2-piece lid and is
heated to a temperature that destroys microorganisms.
•
Pressure canner must be accurate and operated correctly.
•
Heat also inactivates enzymes that can cause changes in
color, flavor and texture.
•
Air is driven from the jar during heating.
•
As the jar cools, a vacuum seal is formed.
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Home Canning Basics
Processing Time
* Each food has its own processing
time.
Follow directions carefully!
* Time differs with size of jar.
* Too Little

Spoilage
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How Canning Process Times
Are Determined
•
Foods are prepared by a specific
procedure.
• The length of time it takes to
adequately heat the coldest spot in the
jar is determined.
• Size of the jar, size of the food,
consistency of the canning liquid, etc.
all have an effect on how heat
penetrates through the product.
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EQUIPMENT
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Jars and Lids
•
Wash canning jars; don’t use if nicked
or scratched – keep hot until used
•
•
ALWAYS use new flat lids
Follow package
instructions
to prepare 2-piece lids
and ring bands
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Home Canning Basics
Vacuum Seal
•
•
•
Holds the lid on the jar.
Prevents recontamination of the
food.
Prevents air from drying out the
food.
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Testing for Seals
•
Listen for “pop”
•
Lid curved inward, won’t move
when pressed
* Clear ringing sound when tapped
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Packing Methods
Raw/Cold Pack


Use fo foods that lose their shape when
cooked
Raw food put into jars

Boiling hot liquid is poured over the
food

Pack firmly, don’t crush
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Hot Pack







Preferred method for most foods.
Food is cooked in liquid before
packing
Cooking liquid poured over food in
jar
Fewer jars needed
Less floating
Better color and flavor
Easier to pack, foods pliable
Note: If directions say only
hot pack then hot pack!
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Headspace
•
Is the space in the jar between the
inside of the lid and the top of the
food or it’s liquid
• Check directions for the correct
headspace
* Usually:
 1/4” jellied fruit products
 1/2” fruits, tomatoes and pickles
 1” to 1-1/4” low acid foods
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Headspace
* Too little
Food may bubble out during
processing
 Deposit on rim may prevent sealing

* Too much
Food at the top is likely to discolor.
 Jar may not seal properly, as all the
air may not be forced from jar during
processing

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Pressure Canning
Low Acid Foods
pH greater than 4.6






Meats
Poultry
Seafood
Generally all vegetables
Soups
Mixed canned foods
(low acid + acid)
 However, if pH < 4.6 =
acidified foods
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Pressure Canners vs. Cookers

To be considered a pressure canner
for USDA processes, the canner
must be big enough to hold at least
4 quart-size jars

Pressure cookers/saucepans with
smaller volume capacities are not
recommended for use in canning

Enough heat may not be delivered
during pressurizing and the cool-down
period in smaller pressure
cookers/saucepans
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Pressure Canner Features

Flat rack in bottom

Pressure regulator or indicator

Dial or weighted gauge

Vent pipe (port) for pressurizing

Safety valves or overpressure plugs

Safety locks when pressurized

Flexible gasket in lid
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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

Pressure is increased or decreased by
adjusting burner heat.
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Pressure Canners Features

Weighted Gauge

Regulates pressure inside the canner

Open vent is the same one that
pressure regulator fits

Will continue to allow some air to be
released from canner during process

Can’t be tested for accuracy
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 Weighted

Gauges cont’d
One piece


Fitting for 5, 10 or 15 pounds
Do not use dead- or counter-weight from
dial gauge canner or pressure cooker.
• Mirro: “jiggles” 3 to 4 times per minute.

Three piece

Number of pieces used determines 5, 10
or 15 pounds
• Presto: rocks gently throughout entire process.
• Mirro: “jiggles” 3 to 4 times per minute.
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Pressure Canner
How it Works
 Steam
inside the pressurized
canner circulates around the jar
 Transfers
 Food
heat by conduction
in center of jar much reach
240°F
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Pressure Canner Processing

Use 1 inch headspace in jars.


A few products use 1-1/4”
Have 2” to 3” of water simmering or hot in
canner.


Hot packed jars – simmering water, 180 F
Raw packed jars – warm to hot water, 140 F

Place jars on rack in canner.

Put lid on canner with weight
off or petcock open.
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Venting the Canner

Also called “exhausting” the canner.

As the water boils in the canner, the “empty”
space becomes a mixture of steam and air.

The temperature of a steam/air mixture is
lower than the temperature of pure steam.

Venting eliminates (“exhausts”) the air so
processing takes place in a pure steam
environment.
 Process times are intended only for a pure
steam environment.
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Venting the Canner, cont.

Some manufacturers of weighted gauge
canners say venting is not necessary.

USDA instructs to vent ALL pressure
canners.
 The one difference in “following
manufacturer’s directions” if not included
there.

Without proper venting, up to 30% of the
sterilizing value of a 20-minute process may
be lost.
 At 10 pounds.
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Venting the Canner, cont.

Steam must flow freely from the open vent port in the
lid for 10 minutes prior to pressurizing.
 After putting filled jars in the pressure canner, fasten
the lid in place.

Leave the ventport open.
• Pipe where weighted gauge or dead weight will
go.

Turn the heat on high.

When water boils, steam will start to come out of
open vent.

Wait until there is a constant, strong funnel of steam,
then start timing 10 minutes.

At the end of the 10 minutes, place weight in place to
start the processing for the time sprecified in the 44
directions.
Loss of Pressure

Drop in pressure during processing means
the sterilizing value of the process will be
decreased.
 Underprocessing.

Foodborne illness (botulism) and/or spoilage
could result.

If pressure drops below target anytime
during the process time, bring the canner
back up to pressure and start timing the
process over, from the beginning.
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Fluctuating Pressure

Large and/or quick variations in pressure
during processing may cause loss of
liquid from jars.

If the variation is a drop in pressure after
process has begun, it also means the
process must be started over.
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Opening the Pressure Canner

Turn off the heat at end of process and let
jars cool in canner until pressure is 0
(Dial gauge should read zero)

Wait 10 minutes to remove the canner lid.

When the canner lid is opened, tilt it so the
steam is pushed away from your face.

The steam, water and jars in the canner will
still be very hot, even bubbling or boiling.
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Hot Water Bath
Canning
Tomato-Pepper Salsa
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Prepare the Canner
• The canner must have a
rack in the bottom
• Fill the about half full of
water, and begin heating
• There must be enough
water so the filled jars
will be covered with 1 to
2 inches of water
• The temperature should
be about 180°F when it
is time to add your filled
jars
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Prepare the Tomatoes
•
•
•
•
•
Wash tomatoes. Make an “x”-shaped slit in
the skin at the base of each tomato.
Dip washed tomatoes into boiling water for
30-60 seconds until skins just begin to split.
Then dip immediately into cold water.
Slip the skins off the tomatoes and core
them.
Chop the tomatoes into small pieces.
Measure out the required amount.
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Prepare peppers
 Caution:
Wear plastic or rubber gloves and do not touch
your face while handling or cutting hot peppers. Wash
hands thoroughly before touching your face or eyes.
Wash the peppers well.
Cut the peppers
lengthwise. Remove the stems and white
membranes. Remove seeds; the more seeds
you remove, the milder the salsa will be.
Chop the peppers into small pieces. Measure
out the required amount.
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Prepare onions and garlic
Remove the outer skin.
Wash the onion and
garlic cloves well.
Cut away any tough stem or root end parts.
Chop the onions into small pieces. Use a
garlic press to finely mince the garlic (or chop
very small by hand).
Measure out the required amount of each.
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•
•
•
•
Cook Salsa Mixture
Canned salsa is a hot pack.
1. Combine all the measured prepared
vegetables in a large saucepan with the vinegar
and seasonings.
2. Bring to a boil, stirring frequently.
3. Reduce the heat and simmer for 20 minutes,
stirring occasionally.
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Fill Jars: Part 1
•
•
•
•
1. Pour the hot salsa
mixture into clean, hot
canning jars.
2. Use a ladle and a
funnel to avoid getting
salsa on the sealing
surface (and prevent a
big mess!)
3. Leave ½”HEADSPACE
4. Liquid should cover
the salsa mixture
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Fill Jars: Part 2
• 5.
Remove air bubbles and adjust headspace
if needed, leaving ½” empty. Use a plastic
knife or special bubble remover tool. Do not
use metal knives or spoons.
• 6. Wipe the rims (top surface) of the jars with a
dampened clean paper towel, to make sure no
food or liquid is on them. This could interfere
with sealing.
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Place Lids on Jars
1.
Remove the pretreated lids from the warm
water
2. Apply the lids to the tops of the jars.
3.
Tighten the ring bands over the lids until
“fingertip-tight” and snug. DO NOT over
tighten and cut through the warm gasket.
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Place Jars in Canner
Water Temperature should be about
180°F (simmering)
Carefully add the jars to the canner,
using a jar lifter.
Keep
jars straight up; do not tilt.
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Processing
 After all the jars are in the canner, make sure the
water is 1 to 2 inches over the tops of the jars.
Place the lid on the canner.
Turn the heat on high and
bring the water in the canner
to a full boil over the jars.
After the water is fully
boiling, process the jars for
the required process time.
The water must never stop
boiling. If it does, return the
water to a boil and start timing
the process again.
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Removing Jars
Turn off the burner.
Remove the lid, turning away from you to avoid getting steam
in your face Leave the jars in the canner for 5 minutes.
Using the jar lifter, remove the jars from the canner, not tilting
Place on a thick clean towel, or plastic or wooden cutting board
to cool. Do not sit the jars directly on a cool surface.
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Cooling Jars
If jar seals properly, the lid will be curved
inward and there will be a clear ringing sound
when tapped.
Let jars sit undisturbed while they are
cooling (between 12-24 hours).
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Storing Home Canned Food
 Remove ring bands from sealed jars
 Gently wash the lid area and
threads of the jar removing
any food or liquid residues
 Rinse and dry; label
and date

Store without ring bands in
a cool, dark, dry place
 Refrigerate unsealed jars
 Avoid temperature extremes
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Disclaimer and Credits
Disclaimer:
 Trade and brand names are used only for information. The
Cooperative Extension Service, University of Georgia College of
Agricultural & Environmental Sciences and College of Family &
Consumer Sciences, and the U.S. Department of Agriculture do
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:
 Permission is granted to reproduce these materials in whole or
in part for educational purposes only (not for profit beyond the
cost of reproduction) provided the author and the University of
Georgia receive acknowledgment and this notice is included:
 Reprinted (or Adapted) with permission of the University of
Georgia. Andress, E.L. 2003. Freezing fruits and vegetables at
home (slides). Athens, GA: The University of Georgia,
Cooperative Extension Service.


This material is based upon work supported by the Cooperative
State Research, Education, and Extension Service, U.S. Department
64
of Agriculture, under Agreement No. 00-51110-9762.
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
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