Let’s Get Ready to Preserve –
An Update on Canning Research
June 3, 2013
Barbara Ingham
Paola Flores
Need Help with Tonight’s Program?
• Help Desk: 800-442-4614
• Phone in to today’s program
o Toll: 630-424-2356
o Toll Free: 855-947-8255
o Passcode: 6774570#
• Tonight’s program archived:
o www.foodsafety.wisc.edu/preservation.html
Tips for a Successful Canning Season
1) Start with a research-tested recipe. Just because a recipe is
in print, doesn’t mean it’s safe for you and your family.
2) Use up-to-date recipes. We all want to continue with those triedand-true recipes, but canning recommendations can, and do, change!
3) Start with equipment in good working order. Test
equipment before use. Be sure to test dial canners!
4) Assemble jars, lids and other equipment. Use jars, lids and
other equipment designed for home food preservation.
5) Leave your creativity behind. Follow an up-to-date, tested
recipe.
Resources for You!
Extension recipes are designed to help you prepare safe,
high quality foods for family and friends.
• UW-Extension www.foodsafety.wisc.edu
• National Center for Home Food Preservation
www.uga.edu/nchfp
o How do I….Can? Freeze? Pickle?
• University of Georgia publications
o So Easy to Preserve (Book and Video)
o www.setp.uga.edu
• Ball Canning www.freshpreserving.com
URL: www.uga.edu/nchfp
Univ. of Georgia:
So Easy to Preserve
Flavored Vinegars
Jellied Products without Sugar
How do I? ….. Can, Pickle, Dry
Getting Started…Recipes
• Use ONLY up-to-date, research-tested recipes!
Current canning instructions date from 1994
• Don’t (necessarily) do what Mom said (or did)!
o Add ACID to tomato products when canning
o Avoid using ALUM in pickling
o Use LIME with care when making pickles
o Be sure to include a heat-processing step as part of
each home canning recipe.
• No tested recipe….no problem. Prepare the
recipe and store refrigerated or frozen.
7
Getting Started…Canners
Boiling Water Canners
• Use for naturally high acid foods
(most fruits) or acidified foods
(pickles, salsa)
• A rack is needed to lift jars off the
bottom
• Use with a tight-fitting lid
• Processes food at 212°F
8
Getting Started…Canners
Pressure Canners
• Use for low acid foods (meat,
vegetables)
• Dial gauge – checked every
year for accuracy!
• Weighted gauge – inspect for
proper function
• Fitted with a rack
• Processes food at 240°-250°F
9
How do we know which canning
method to use?
What is the pH (acidity) of the food?
below
pH 4.6
above
HIGH Acid
Boiling Water Canning
Fruits, Pickles, Salsa
LOW Acid
Pressure Canning
Meat, Vegetables
10
What if…..
For high acid foods you didn’t have
to:
•Wait for all that water to boil?
•Use so much water?
•Take so much time to process food?
Introducing….The Atmospheric
Steam Canner
Lack of research means that Extension does not currently support the use
of atmospheric steam canners.
Atmospheric Steam Canning
Paola Flores Verdad Ixta
About Paola
• 1ST year Food Science M.S. student
• Graduated from Purdue University
• B.S. in Food Science
• Getting married in December! 
Canning
• What is it?
– Preserving food either at home or commercially
• Why is it important?
– Preserving the harvest – extending shelf life
– Catering to special dietary needs
– Growing consumer trend
• What research has already been done?
– Boiling water canners & pressure canners
(USDA Complete Guide to Home Canning, 2009)
nchfp.uga.edu/publications/publications_usda.html
pH, Heat, and Safe Home-Canned
Foods
• Acid or Acidified Foods
– Heat is required to destroy target pathogens and vegetative cells of
spoilage organisms
– High acid (pH <4.6) ensures that spores of Clostridium botulinum will
not germinate
– E. coli O157:H7 is the target pathogen in thermal steps
– Yeasts & Fungi or heat resistant enzymes are also of interest as they
pertain to food spoilage
• Pasteurization (heating):
– Removes air entrapped in product and in headspace, allowing a
vacuum seal to form on cooling
– Helps to ensure that a strong hermetic (air-tight) seal forms
Research is key for safe homepreserved food
• Use of an up-to-date, research tested recipe is key for home
canners. Sources of information:
– National Center for Home Food Preservation
www.uga.edu/nchfp/
– Ball Canning www.freshpreserving.com
– Extension bulletins www.foodsafety.wisc.edu/preservation.html
• And a whole lot of untested, sometimes ‘scary’ information
posted to the web that is not tested
–
–
–
–
–
Canning fish in the dishwasher
Using a washing machine to clean cucumbers prior to pickling
Oven canning of meat
Filling salsa into jars, applying lids, and putting on shelf
Filling hot jam into jars, sealing and inverting
Steam Canners
• What are they?
• How are they assumed to work?
– Heat transferred from steam through jar and into food
• Why are they growing in popularity?
• What foods could be safely canned in a steam canner?
– Processing times have not been adequately researched to allow
Extension educators to recommend use of these canners.
Research Timeline
Spring/Summer 2013
• Goal: To establish, under varying conditions, heating patterns in an
atmospheric steam canner (ASC) and compare those to patterns in
a boiling water canner (BWC)
– Establish come-up time for each canner, i.e. when do we ‘start the clock’?
– Determine the time for the cold spot in the center of a jar to reach a
predetermined temperature in an ASC and BWC.
Fall 2013
•
Goal: Using inoculated pack studies, to verify processing times for ASC
(atmospheric steam canner) as compared to established processing times
for BWC (boiling water canner)
Inoculate with E. coli O157:H7, Salmonella spp., Listeria monocytogenes
Spring 2014
–
• Goal: Determine if a re-configured BWC can be used as an ASC
• Goal: Updating of national outreach materials to include ASC
recommendations, where appropriate
Methods & Procedures ASC
– Hot (~180˚F) or Room Temp (~75˚F) tomato juice
– Quarts (7), Pints (8), Half Pints (8)
– Start with room temperature environment
& heated jars
– 4 thermocouples at varying depths
– Measured come up time and venting time
1
Vent hole
2 3
4
Vent hole
Example Data Graph
7 Quart Jars Room Temp Juice (ASC)
250
Temperature (degrees F)
200
Canner at RT
7 Quart jars filled with RT juice
added
Full Steam
First Steam Column
150
1
2
3
100
4
50
Time for the canner to
reach the processing
temperature: ~18 minutes
0
0:00:00
0:02:53
0:05:46
0:08:38
0:11:31
0:14:24
Time
0:17:17
0:20:10
0:23:02
0:25:55
0:28:48
Results to Date
• Heating patterns depend on jar placement and quantity
• Generally:
–
–
–
–
Smaller jars will take less time
Smaller quantities will take less time
Higher temperatures will take less time
Statistics are showing that process is not highly variable when
comparing similar environmental factors
• Many variables (for us and consumers) :
•
•
•
•
•
•
Stove
Room
Thermocouple variability
Visual cues & matching with concrete data
Jar placement
Amount of jars
Calculations
• Compare area under curve to analyze differences between
runs 250
Temperature (degrees F)
200
150
1
2
100
3
4
50
0
0:00:00
0:07:12
0:14:24
0:21:36
0:28:48
Time
Calculate Thermal Process Lethality.
Process lethality can be compared across runs to determine how
to adjust tested recipes for use in an Atmospheric Steam Canner.
Future Research
– Processing time:
• Time period that given jar size should be held at a set
processing temperature in order to achieve the required
thermal destruction of microorganisms likely present in
slowest heating point of container.
– 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
• Convection (liquid food) = ¾ inch from bottom
• Convection & Conduction (liquid & solid) = center of jar
Thermocouple inserted into coldest spot within jar
Expected Outcomes
• Determine what adjustments need to be made to
Boiling Water Canning instructions so they can be
safely used for Atmospheric Steam Canners.
– Research results sent out for review Fall 2013
– Results published ~Spring 2014
• Write consumer guide to steam canning
– Provide consumers simple instructions for safe steam
canning of high-acid foods
Research project results will be
posted to:
www.foodsafety.wisc.edu
The “Bottom Line”
Assuring safety in Atmospheric Steam Canners:
• Use ONLY for fruits and acidified vegetables
• Use ONLY with tested recipes
• Use the correct amount of water & approved
equipment
• Time once a full column of steam is emitted (8-10”)
• Keep canner steaming the entire time
• Process for the full time required
And next …in our Lunch & Learn
series
June 17, 2013
12 noon – 1 pm
Making Jams & Jellies
Preserve the taste of perfectly ripe fruit in homemade jams
and jellies and consider new gift ideas in jellied fruit and
vegetable products.
Archives will be posted to:
www.foodsafety.wisc.edu
Questions & Comments