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.