Let’s Get Ready to Preserve –An Update on Canning Research

June 3, 2013Barbara Ingham

Paola Flores

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• Tonight’s program archived:owww.foodsafety.wisc.edu/preservation.html

Tips for a Successful Canning Season1) 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 tried-and-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/nchfpoHow do I….Can? Freeze? Pickle?

• University of Georgia publicationsoSo Easy to Preserve (Book and Video)owww.setp.uga.edu

• Ball Canning www.freshpreserving.com

How do I? ….. Can, Pickle, Dry

Univ. of Georgia:So Easy to PreserveFlavored Vinegars Jellied Products without Sugar

URL: www.uga.edu/nchfp

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)!

oAdd ACID to tomato products when canningoAvoid using ALUM in picklingoUse LIME with care when making pickleso 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.

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Getting Started…CannersBoiling 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

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Getting Started…CannersPressure 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

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How do we know which canning method to use?

What is the pH (acidity) of the food?below pH 4.6 above

Boiling Water Canning Fruits, Pickles, Salsa

Pressure CanningMeat, Vegetables

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HIGH Acid LOW Acid

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 CanningPaola 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 home-preserved 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 TimelineSpring/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 monocytogenesSpring 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 2 3 4

Vent holeVent hole

Time for the canner to reach the processing temperature: ~18 minutes

Example Data Graph

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

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, 201312 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