PRESTO precise 02144 Digital Pressure Canner Instruction Manual
- June 4, 2024
- PRESTO precise
Table of Contents
Easy, confident, and
sustainable home canning.
Canning
BASICS
Current terminology and instruction for safe, confident home canning.
Canning Introduction
The key to successful canning is to understand the acidity and spoilage factor
of the food you wish to can, as well as the acceptable canning methods to
process those foods. Invisible microorganisms exist naturally on fruits,
vegetables, meat, poultry, and seafood. Yet they are not a problem unless food
is left to sit for extended periods of time, causing food spoilage. This is
nature’s way of telling us when food is no longer fit to eat.
There are four basic agents of food spoilage— enzymes, mold, yeast, and
bacteria. banning will interrupt the natural spoilage cycle so food can be
preserved safely.
Molds, yeast, and enzymes are destroyed at temperatures below 212°F, the
temperature at which water boils (except in mountainous regions). Therefore,
boiling water canning is sufficient to destroy those agents.
Bacteria, however, are not as easily destroyed. The bacterium Clostridium
botulinum produces a spore that makes a poisonous toxin hich causes botulism.
This spore is not destroyed at 212°F. In addition, this bacterium thrives on
low-acid foods in the absence of air. Therefore, for a safe food product, low-
acid foods need to be processed at 240°F, a temperature only achieved with
pressure canning. As jars of food cool after processing (by either the boiling
water method or pressure canning method), a vacuum is formed sealing food
within and preventing any new micro-organisms from entering and spoiling the
food.
Determining the Correct Canning Method
The level of acidity in the food being canned determines which method of
canning is required, either boiling water canning or pressure canning. For the
purpose of home canning, foods are categorized as low acid and high acid.
Low acid: Foods that are low acid have a pH value higher than 4.6 and
include vegetables, meats, poultry, and seafood. Low-acid foods must only be
processed using the
pressure canning method.
High acid: Foods that are high acid have a pH value of 4.6 or less and
include fruits, jams, jellies, properly pickled vegetables, and properly
acidified tomatoes. Most fruits are naturally high in acid. Pickles and
tomatoes, which are not high acid, are made high acid with the addition of
vinegar, lemon juice, or lime juice. High-acid foods can be safely processed
using the boiling water method.
Tomatoes and fruits can be safely processed using either the boiling water
method or the pressure canning method. However, always follow the processing
method stated in the research-tested recipe.
Current stovetop Presto ® Pressure Canners and the Presto Precise ® Digital
Pressure Canner function as both a pressure canner and a boiling water canner
providing complete versatility and easy storage.
Preplanning
Prior to the canning season, thoroughly examine your pressure canner. Whether
you have a new canner or a trusted old canner, it’s important to do a trial
run with water to ensure it is functioning acceptably. As a general rule,
replace the sealing ring and overpressure plug at least every three years. If
your canner has a dial gauge, we recommend having it tested at your county
extension office or with the manufacturer to ensure its proper operation.
Finding a problem with a full load of vegetables in the canner can be
disheartening.
Selecting a Recipe
To produce home canned food that is safe for storage at room temperature, it
is necessary to use a tested canning recipe. Recipes that have been handed
down through the years or those found on the web are oftentimes unreliable and
usually do not include scientifically tested processing procedures that are
vital to a successful and safe canning project. Canning information published
prior to 1994 may be incorrect and could pose a serious health risk. A tested
canning recipe has been evaluated to determine the accurate processing method
(boiling water canning or pressure canning) as well as the preparation
instructions and processing time. Do NOT can leftovers; it is not safe.
Always choose recipes from a reliable resource, such as the National Center
for Home Food Preservation (nchfp.uga.edu), your local Cooperative Extension
Service, the GoPresto.com website or by calling
National Presto Industries, Inc. at
800-877-0441.
Assembling Supplies
Assemble all ingredients, supplies, and equipment needed for your canning project. Carefully read, understand, and follow the recipe and canning instructions as directed. Do ot substitute or omit ingredients.
Selecting Jars
Glass home canning jars, sometimes referred to as Mason jars, are the only
jars recommended for safe home canning. They are available in standard sizes
(half-pint, pint, and quart jars) and will withstand the heat of a pressure
canner, time after time.
Note: Half-gallon jars are recommended only for canning clear juices,
such as grape and apple. Glass home canning jars offer a deep neck and wide
sealing surface to assure a tight seal. Always visually examine canning jars
for nicks or cracks. Recycle or discard any damaged jars. Do not use jars from
commercially prepared foods because they were made for single-use only. Always
use the jar size and exact processing procedures indicated in the research-
tested processing recipe.
Cleaning Jars for Canning
Jars should be thoroughly washed in hot, sudsy water. Do not use wire brushes,
abrasive materials, or cleansers because they may damage the glass. Rinse jars
completely with hot water. To help prevent jar breakage, allow jars to stand
in very hot water prior to filling them with food. A dishwasher may also be
used. Wash and dry jars using a regular cycle. When cycle is complete, remove
one jar at a time, keeping the rest of the jars heated until needed.
Jars do not need to be sterilized unless the food placed in them will be
processed less than 10 minutes using the boiling water method, such as jams
and jellies. To sterilize the jars, boil them for 10 minutes. If you live at
an altitude of 1,000 feet or more, boil an additional minute for each
1,000foot increase in altitude. If you wish, rather than sterilizing jars, the
processing time can be increased to 10 minutes for those jams and jellies that
have a processing time of 5 minutes. The additional processing time is not
harmful to most gels. Keep in mind that if your altitude is above 1,000 feet
the processing time needs adjustment.
Canning Lids and Bands
The two-piece vacuum lid is the recommended closure for home canning. It
consists of a flat metal lid with a sealing compound on the outer edge and a
separate metal screw band that secures the lid during processing. The bands
can be used repeatedly if they remain in good condition; however, new lids
must be used each time. Always prepare lids and bands according to the
manufacturer’s instructions.
Avoid closures such as zinc caps and glass lids that require a jar rubber.
These closures do not provide a proper method to determine if the seal is
safe. Also, avoid commercial one-piece caps even if they have a rubber-like
gasket because they are intended for one-time use only.
Selecting and Preparing Food
Select only produce that is at its peak quality. Produce that is overripe or
damaged will not be a good canned product. Always follow exact preparation
instructions such as feeling, slicing, or chopping. Altering the recipe may
affect the heat penetration of the food which when canned may result in
underprocessing.
There are two methods of packing food into jars: raw packing and hot packing.
Recipes will indicate a packing method that is best for the food being canned.
In some cases, both raw and hot packs are indicated. If given a choice, the
hot pack method yields better color and flavor, especially when foods are
canned using the boiling water method.
Raw Pack: Unheated food is put directly into the jars and then covered
with boiling water, juice, or syrup. When raw packing meat, poultry, fish, and
seafood, do not cover them with liquid. Most food should be packed tightly in
jars because it will shrink during processing. However, corn, lima beans,
peas, and potatoes expand during processing and should be packed loosely. Raw
meat, as well, should not be packed tightly. Always refer to the recipe for
specific pack instructions.
Hot Pack: Food is heated to boiling or cooked according to the recipe
before being packed into jars. The food is then covered with boiling liquid.
Foods that are hot-packed should be put into the jars loosely because
shrinkage will not occur during processing. Precooking the food allows it to
conform to the jar better for a tighter, more efficient fit and prevents food
from floating up in the jar during processing.
Preparing Filled Jars for Canning
Measuring Headspace
All recipes will indicate the amount of headspace necessary for the food being
canned. Headspace is the air space between the top of the food or its liquid
and the lid. Leaving too much headspace can result in underprocessing because
it may take too long to release the air from 
the jar. Leaving too little headspace will trap food between the jar and the
lid and may result in an inadequate seal. As a general rule, allow ½-inch
headspace for fruits and tomatoes, 1-inch for vegetables, meats, and seafood,
and 1¼-inch for poultry.
Removing air bubbles, Preparing jar rims, and Adjusting lids
After food has been packed in jars, work quickly to remove air bubbles that
have become trapped between pieces of food by moving a clean, nonmetallic
spatula around the jar between the food and the side of the jar. The use of
metal utensils can damage canning jars and should be avoided. Immediately wipe
jar rims with a clean, damp cloth to remove any residue. Place flat lid on the
rim of jar making sure sealing compound is touching the glass. Position a band
over the lid and screw it onto the jar just until resistance is met. Not too
tight, as air must release from the jars during processing and cooling. When
all the air is released, a vacuum is formed and the lid seals.
Processing
Process food according to the research-tested canning recipe which will
provide information on the processing method to use, boiling water method or
pressure canning method. It will also state the processing time for the
boiling water method or the processing pressure and time for the pressure
canning method.
Cooling and Storing Jars of Food
Cooling Jars
Carefully open the cover. Using a jar lifter, remove jars from the canner
lifting them straight up, being careful not to tilt them. Place jars on a dry
towel on the countertop away from drafts leaving 1 to 2 inches of space
between jars to allow for even cooling. Do not invert jars or cover them with
a cloth. Allow jars to cool naturally and completely. Let jars cool for 12 to
24 hours before checking the seals. It is important to test the seals to be
sure a vacuum has been formed. Press down on the center of the lid. If it is
concave or stays down when pressed, the jar is properly vacuum sealed.
Storing Canned Food
Remove bands. Wipe off any food residue from lids and jars. Do not replace
bands as they may rust and become difficult to remove. Date and label jars
before storing. Store canned food in a cool (between 50° and 70°F), dark, and
dry place to maintain optimum eating quality for up to one year. Storing food
near a heat source or with exposure to sunlight can cause a loss of food
quality in just weeks or a few months.
Detecting Spoilage
If up-to-date instructions and processing times and pressures are followed
carefully, spoilage is uncommon. However, it is still recommended to check for
signs of spoilage before tasting any canned food. Check for a broken seal,
gassiness when opening, mold, sliminess, cloudiness, or unpleasant odors. If
any of these signs are present, discard the good. As a safeguard against using
canned low-acid and tomato products which may be affected with spoilage that
is not readily detected, boil food for 10 minutes for altitudes up to,000 feet
above sea level. Extend the boiling time by 1 minute for each 1,000-foot
increase in altitude. Many times odors that cannot be detected in the cold
product will become vident by this method. If, after boiling, food does not
smell or look right, discard it without tasting it.
For more canning information
and recipes for your Presto® Pressure Canner, visit
GoPresto.com
National Presto Industries, Inc.
3925 North Hastings Way, Eau Claire, WI 54703
©2022 National Presto Industries, Inc. ADW19-5825D