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Tag: Food Preservation

Canning Previously Frozen Tomatoes

Posted on by Karen Blakeslee

So you saved your tomato crop in the freezer. Can those frozen tomatoes be canned?

It is not recommended to can tomatoes that froze on the vine. This is because the acid content changes too much, while on the vine, making them unsafe for canning.

But tomatoes harvested prior to a fall freeze, then frozen, do not change in acidity. What does change is their texture and how they measure.

The best choice for canning previously frozen tomatoes is to make a well cooked product such as a stewed or crushed tomato product, or made into tomato juice or sauce.

It is not recommended to can them whole or quartered. They will pack into the jars differently, absorb moisture differently, and the heat transfers through the jars differently. This could lead to under processing and spoilage. Tomato canning recipes are based on fresh tomatoes.

Source: University of Georgia

 

Fresh Lemons vs. Bottled Lemon Juice for Canning

Posted on by Karen Blakeslee
lemon juice
Use bottled lemon juice in all canning for safest results.
Photo: Canva.com

Whether adding lemon juice to tomatoes to acidify them safely or adding lemon juice to a jelly or jam, the best and safest choice is bottled lemon juice. Here’s why.

Bottled lemon juice is standardized, or uniformly acidified, per FDA regulations. Therefore, it is consistent which provides a known level of safety for food preservation. The final acidity of a food product is critical to deter the growth of microorganisms that can cause spoilage or foodborne illness.

Fresh lemons, however, have an inconsistent acid, or pH, level. This can vary within the same variety of lemons, but also vary due to maturity, growing conditions, soil, fertilizer, rootstock, and storage conditions. While safe to eat fresh for a great meal, they are not the safe choice for food preservation.

As a reminder, when canning tomatoes, they must be acidified by using bottled lemon juice, citric acid, or vinegar with 5% acidity. Here are the choices and recommended usage levels:

  • Bottled Lemon Juice
    1 tablespoon per pint
    2 tablespoons per quart
  • Citric acid
    1/4 teaspoon per pint
    1/2 teaspoon per quart
  • Vinegar with 5% acidity
    2 tablespoons per pint
    4 tablespoons per quart

Sources: Iowa State University AnswerLine and K-State Research and Extension

 

Choosing Vinegar for Pickling and Canning

Posted on by Karen Blakeslee
vinegar
Photo: KSRE RRC

First step, read the label. Look for vinegar that is 5% acidity.

Today’s recipes, including Extension and USDA food preservation recipes, use vinegar that has 5% acidity. Not all vinegars are the same. They range from 2.5% to more than 6%. Therefore it is important to read the label or ingredient statement to verify the acidity level.

The National Center for Home Food Preservation at the University of Georgia gives these recommendations if you have used a vinegar with  less than 5% acidity.

  • If your canned food has been preserved for less than 24 hours using 4% vinegar, it is advisable to store the jars in the refrigerator to maintain the safety and quality of the product.
  • If your canned food has been preserved for more than 24 hours using 4% vinegar, it is advisable to discard the product.

 

Check Canning Lids for Defects

Posted on by Karen Blakeslee
lid defect
Uneven sealing compound
Photo: courtesy Susan Stich

Canning lids are essential for canning food. When preparing lids to use, take a look at them to be sure they are in good condition to reduce problems after canning.

Always used new lids, never reuse canning lids as the rubber seal is already indented and the lid was likely bent when removing it from the jar.

Wash new lids in hot, soapy water. That’s it! Do not boil them as that step is no longer required. Boiling the lids can lead to seal failures.

Look at the underside of the lid. Defects can happen, such as the irregular sealing compound on the lid in the picture. This can lead to seal failures. Contact the manufacturer to report the problem.

 

Jam and Jelly Problems and Solutions

Posted on by Karen Blakeslee
peach jam
Source: NCHFP
Photo: KSRE RRC

Sometimes jam and jelly recipes just don’t turn out right. So here are some problems, causes, and prevention strategies.

Learn more about other problems and solutions for jam and jelly at https://nchfp.uga.edu/how/can_07/jellyproblems.html

 

PROBLEM CAUSE PREVENTION
Too soft Overcooking fruit to extract juice Avoid overcooking as this lowers jellying capacity of pectin
Used too much water to extract juice Use recommended amount
Incorrect amounts of sugar and juice Measure correctly
Undercooking jam or jelly mixture Follow cooking times exactly
Insufficient acid Lemon juice may need to be added
Making too large of a batch Make only one recipe at a time
Moving finished jars too soon Allow finished jars to sit at least 12 hours
Insufficient time before using Some fruits take up to 2 weeks to set completely

A Caution About Preserving White Peaches

Posted on by Karen Blakeslee

It’s almost peach season and many will be preserving this summer favorite in various tasty treats.

White fleshed peaches, however, cannot be canned like yellow peaches. White peaches are low acid so traditional canning cannot be done, and that includes water bath canning and pressure canning. No research has been done for safe canning. This includes plain peaches, jam, jelly, or any other mixture.

The best option is to freeze white peaches or eat them fresh.

To preserve yellow peaches, see our Preserve it Fresh, Preserve it Safe: Peaches publication.

Source: University of Georgia

 

Preserving Melons

Posted on by Karen Blakeslee
cantaloupe
Fresh cantaloupe
Photo: USDA ARS

Melons are another summer treat! They are best eaten fresh, but there freezing them for later use is an option.

Rinse with water and scrub the rind to remove dirt, then dry. Slice the melon into cubes or use a melon baller. Place pieces on a parchment-lined baking sheet and freeze. Then place frozen melon pieces in a freezer container. Just know the texture may change during freezing.

Melons, by themselves are not suitable for canning. In fact, they are a low acid food. There are a couple options to make cantaloupe into pickles or a conserve at www.canr.msu.edu/uploads/resources/pdfs/melons_(e3250).pdf. Watermelon rind can be made into pickles also. See https://nchfp.uga.edu/how/can_06/watermelon_rind.html.

 

Why is Headspace Important in Canning?

Posted on by Karen Blakeslee
Headspace
Photo: USDA Complete Guide to Home Canning

Headspace is the space in the jar between the inside of the lid and top of the food or its liquid.  The amount of headspace needed depends on the type of food being processed.

If the jars are filled too full the contents may boil out during processing.  Solids or seeds may be caught under the sealing compound and prevent the jar from sealing.

If too much headspace is left at the top of the jar, the processing time may not be long enough to drive out all the extra air from the top of the jar.  This would mean that a tight vacuum seal may not be formed.  Also, the air left inside the jar could cause the food to discolor.

For the correct headspace for each food, check the processing directions for each specific food.

Starchy foods, such as beans or potatoes, tend to swell when heated and therefore require more headspace.

The extent of expansion during processing  it determined by the air content in the food and by the processing temperature.  Air expands more at higher temperatures.

The USDA Complete Guide to Home Canning recommends the following headspace measurements:

  • Jams and Jellies—1/4 inch
  • Fruits and tomatoes to be processed in a boiling water bath—1/2 inch
  • Low acid food to be processed in a pressure canner—1– to 1-1/4 inches

Source: USDA Complete Guide to Home Canning and National Center for Home Food Preservation

 

Freezing Food for the Fair

Posted on by Karen Blakeslee
Fair judging
Kansas State Fair, Photo: KSRE Flickr

To help save time and stress at county fairs, prepare food entries early and freeze them.  Most baked goods freeze well and can still be blue ribbon quality.  This includes cookies, yeast and quick breads, and cakes.  Here are some tips:

  • Bake the product as usual. Cool completely!  This helps prevent condensation inside the wrapping and development of ice crystals.
  • Use moisture-vapor resistant packaging. This includes freezer-safe plastic containers or bags, heavy-duty aluminum foil, and rigid containers.
  • Separate layers of cookies with wax paper or parchment paper.
  • If a cake or bread is to be frosted, freeze the product only and frost after it is thawed.
  • Make pie crusts ahead of time and freeze. Freezing whole prepared pies can cause the filling to soak into the crust.
  • Thaw all baked goods in the freezer packaging. They can be thawed at room temperature.  Remove from the freezer the night before the fair.  Once thawed, repackage into the proper packaging according to your fair rules.

Source:  Univ. of Georgia, www.uga.edu/nchfp/publications/uga/FreezingPreparedFoods.pdf

Source:  Univ. of Georgia, www.uga.edu/nchfp/publications/uga/FreezingPreparedFoods.pdf

 

Safely Preserving Tomatoes

Posted on by Karen Blakeslee
Canned tomatoes
Canned tomatoes, University of Georgia

Tomatoes are borderline in pH between acid and low acid foods, so the USDA preparation directions for these products call for acidification to allow a less severe heat treatment than would be required without it. To ensure safe acidity in whole, crushed, or juiced tomatoes, add two tablespoons of bottled lemon juice or ½ teaspoon of citric acid per quart of tomatoes. For pints, use one tablespoon bottled lemon juice or ¼ teaspoon citric acid. Add acid directly to jars before filling. Sugar may be added to offset an acid taste, if desired, but the acid cannot be decreased to taste.

No matter how you choose to can your tomatoes, all steps in preparing and cooking the foods still need to be followed for the process time(s) printed with them. The process times are very different for tomatoes packed in water compared to tomato juice or without added liquid. For many of these tomato products, there are canning options for both boiling water and pressure canning available in our directions.

Source: https://nchfp.uga.edu/tips/summer/canned_tomato_types.html

See KSRE Preserving Tomatoes for more information

 

Reference to any specific commercial products, process, service, manufacturer, or company does not constitute its endorsement or recommendation. Paid for by Kansas State University