Home Food Preservation: What’s New and What’s Old—and Unsafe!
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Transcript of Home Food Preservation: What’s New and What’s Old—and Unsafe!
Home Food Preservation: What’s New and What’s Old—and Unsafe!
Joye M. Bond, PhD, RDDepartment of Family Consumer ScienceMinnesota State University, Mankato
Food Preservation MethodsCanningFreezingDryingPicklingSugar concentrates
◦Jams, jellies, butters, preserves, etc.
History of USDA Publications1909—Canning Vegetables in the
HomeWWI—Can the Kaiser
WWII—Victory Gardens
Early 1950s—USDA research switched to freezing
Complete Guide to Home Freezing was drafted in 1980s, but never published
Majority of today’s processes are based on USDA research from 1944-46
Some limited research by various universities after USDA stopped
1980s—USDA/Penn State Center of Excellence◦Conducted extensive literature
review◦Evaluated tomato processes◦Fruit pie fillings◦National training for Extension
faculty◦Published Complete Guide to Home
Canning in 1988 (revised in 1989, 1994, 2009)
National Center for Home Food Processing and PreservationUniversity of Georgia—lead
institution◦Literature review◦Updating of USDA/Extension
publications◦New website:
National Center for Home Food Preservation
◦Instructional video series◦Web-based curriculum on home food
preservation◦Original applied research
Applied ResearchMicrobial issues of herbs and
spices used in home food preparation of flavored vinegars, salsas, & oils
Canning fruit with Splenda®
Development of “specialty” foods—salsas, sugar concentrates, relishes, sauces, and marinades
Why Preserve at Home?Save food from a “time of plenty”
to a “time of need”Prevent spoilage until food can
be eatenKnow what is in the foodPersonal satisfaction
How Methods Preserve FoodRefrigeration
◦Extends shelf-life by slowing growth of microorganisms and action of enzymes
Freezing◦Lowered temperature lowers the
available water (Aw)
How Methods Preserve FoodCanning fruits and tomatoes
◦Removal of O2
◦Sealed jar◦Heat (boiling water processed)◦Acidity (natural or added)
Canning vegetables and meats◦Removal of O2
◦Sealed jar◦Heat (pressure processed)
How Methods Preserve Food Sweetening & Acidifying (jams,
jellies, spreads)◦Lower (Aw)◦Removal of O2
◦Sealed jar◦Heat (boiling water processed)◦Acidity of the fruit
How Methods Preserve Food Pickling & Fermenting
◦Increased acidity—added or created◦Heat (boiling water processed)◦Removal of O2
◦Sealed jar
How Methods Preserve Food Drying
◦Lower (Aw)
Home canning is back!And botulism still does occur…
◦July 2012—Oregon, home-canned foods served at a barbecue
◦2008, 2009—Ohio and Washington, green beans
Basics of Home CanningFood in a jar is heated to a
temperature that kills microorganisms
Heat also inactivates enzymes that cause food spoilage
With jars, air is driven from the jars with heating; as jar cools, a vacuum seal is created
Vacuum SealHolds lid on jarPrevents recontamination of foodPrevents air from drying out food
Two Methods of CanningBoiling Water Canning
◦Used for acid foods
Pressure Canning◦Used for low acid foods (and some
acid foods)
Acid FoodspH≤4.6Most fruits (some exceptions,
e.g., melons)Tomatoes are borderline—specific
amounts of citric acid or lemon juice must be added before canning to acidify)
Sauerkraut
pH of Some Common Foods
Acidified FoodspH≤4.6Mixtures of acid and low acid
foods with an equilibrium pH≤4.6
Low Acid FoodspH>4.6Most vegetablesMeats, poultry, seafoodSoupsMixtures of acid and low acid
foods(e.g., spaghetti sauce—meat, vegetables, tomatoes; salsa—tomatoes, onions, peppers)
Why Two Methods?Clostridium botulinum Yeast, molds, and most bacteria
killed fairly easily at boiling temperatures (212˚F at sea level)
C. botulinum forms spores that require a higher temperature for destruction in a reasonable amount of time (usually 240˚F at sea level)
Preventing BotulismSpores won’t germinate in acid
foodsSpores killed when heated long
enough at a specific temperatureUSDA usually recommends 240˚F
at sea levelPressure canner must be used for
all low acid foods
Preventing BotulismProper preparation and process
timeCanner must be accurate and
operated correctlyAltitude adjustments need to
made as neededUse directions from a reputable
source National Center for Home Food Preservation
Beware of “granny’s method”
Methods of PackRaw pack
◦Boiling liquid is poured over the food
Methods of PackHot Pack
◦Cooked in liquid before packing; cooking liquid poured over food in jar
◦Heat in preparation kills some microbes
◦Cooking before packing changes the way food will heat while in the canner, so time might be different than raw pack
Headspace¼ -inch: jellied fruit products½ -inch: fruits, tomatoes, pickles1-1¼ -inch: low acid foods
Boiling Water CanningWater temperature is no higher
than 212˚F Process times increased for
altitudes over 1000 ft
Boiling Water CanningWater is high enough to cover
filled jars by 1-2 inches over top of jars
Filled and closed jars are placed on rack in canner to prevent breakage
Jars are processed for specific time after water comes to a boil
Boiling Water CanningAt end of process time, turn off
heat and remove lidWait 5 minutesRemove jars to a protected
surface to cool
Pressure Canner ProcessingGo to:
http://nchfp.uga.edu/multimedia/slide_shows/CanLowAcid_web08.ppt
Jars and LidsUSDA recommendations based
on 2-piece metal lid systemWash canning jars; don’t use if
nicked or scratched—keep hot until used
Prepare 2-piece canning lids and rings using manufacturer’s instructions
Filling and Closing JarsFill according to recipe
recommendationsRemove air bubblesRe-adjust headspace if necessaryWipe jar rims with clean,
dampened clothAdjust lids fingertight
National Surveys of Home Food PreservationSource of canning instructions
◦Family or friends—51%◦General cookbook—17%◦Ball Blue Book—7.5%◦Pressure canner manufacturer—
12.6%◦Internet—3%◦Magazines, newspapers—4%◦State Extension Service—3%◦Other—13%
SurveysMany people not using pressure
canning for low acid foodsLarge percentage still using
“open kettle” or “oven” methods of canning
Large percentage change recommendations to fit their needs
Recommended ResourcesNational Center for Home Food Pr
eservation | Publications HomeNational Center for Home Food Pr
eservationSo Easy to PreserveAny Land-grant University
Extension ServiceReputable manufacturer books,
pectin packages, etc.
Salsa! http://nchfp.uga.edu/publications
/uga/TomatoSalsa_web.ppt
Salsa!Mixture of low acid and acid foods
(tomatoes, onions, peppers)Hot packUse a tested recipeNeeds to be acidified to be safeDon’t increase the amount of onions
or peppers (both low acid)Can alter amounts of dried spices If you aren’t sure, freeze or refrigerate
the salsa—don’t can it
Resources◦ Adapted from Current Science and Practice in
Home Food Preservation webinar, Elizabeth L. Andress, PhD, Project Director, National Center for Home Food Processing and Preservation, The University of Georgia. August 2012.
◦ Salsa information reprinted with permission of the University of Georgia. National Center for Home Food Preservation and Simmons, H. 2008. Step-By-Step Canning of Tomato Salsa Using Slicing Tomatoes. Athens, GA: The University of Georgia, Cooperative Extension.