AnswerLine • Iowa State University Extension and Outreach

Elevation? Does It Matter?

February 6, 2024 Marlene Geiger 1 Comment

While residents of most midwestern states usually don’t think about their elevation, elevation affects all aspects of food preparation–cooking, baking, canning, jams and jellies, and candy making. As elevation rises, air pressure falls and water boils at lower temperatures making recipe adjustments necessary.

Pan of boiling water on stovetop — Boiling water at 1014 Ft of elevation – Photo: mrgeiger

Elevation and Everyday Cooking and Baking

When it comes to everyday cooking and baking, there are few noticeable effects of elevation until one reaches 3,000 feet. Higher elevations present several challenges when preparing some foods. At higher elevations, leavened products using yeast, baking powder/soda, egg whites, or steam rise more rapidly, may collapse, and may not be fully cooked. Because water boils at a lower temperature at higher elevations, foods that are prepared by boiling or simmering will cook at a lower temperature, and it will take longer. High elevation areas are also prone to low humidity, which can cause the moisture in foods to evaporate more quickly during cooking. At elevations above 3,000 feet, preparation of food may require changes in time, temperature or recipe. For those that find themselves at higher elevations, Colorado State University and New Mexico State University have excellent tips and guidelines for successful baking and cooking.

Elevation and Canning Safety

Because water boils at 212°F at sea level and decreases about 1°F for each 500-ft increase in elevation, adjustments must be made when canning foods at home to ensure home-canned foods are processed safely. The amount of time that jars are held at a certain temperature during canning is important to producing a safe product. Processing times for most recipes are based on elevations of 0-1,000 feet unless stated otherwise. When elevations are above 1,000 feet, extra time is added for food processed in a water-bath canner. For food processed in a pressure canner, extra pressure is added. Both adjustments are needed to get to their respective safe processing temperatures for high acid and low acid foods.

USDA and National Center For Home Food Preservation (NCHFP) recipes include a table for proper processing based on elevation to insure sufficient time and temperature have been reached for a safe, shelf-stable product. In the NCHFP table for Crushed Tomatoes, note that time is increased in 5 minute increments as elevation increases for boiling water canning and pounds of pressure is increased for pressure canning. (Crushed tomatoes are one example of a food that can be processed by either boiling-water bath or pressure.)

While time is adjusted for water-bath canning, pressure regulation differs by the type of pressure canning equipment used—dial- or weighted-gauge canner.

Elevation and Sugar Concentrations

Elevation is also a factor in candy making and the gelling of jams and jellies when pectin is not used. At higher altitudes, atmospheric pressure is less so water boils at lower temperatures and evaporates more quickly. Syrups become concentrated and reach the gel point at a lower temperature. The concentration of sugar required to form a gel is in the range of 60 to 65 percent which occurs at 217 and 220 degrees F, respectively, at sea level. As elevation increases, the gelling point decreases by 2 degrees per 1,000 feet. When elevation is not taken into consideration, overcooked jam is the result as too much water has boiled away leaving a sugar concentration that is too high, leaving a jam that is gummy, dark in color or tough. The same is true for candy making. For each 1,000 feet above sea level, reduce the temperature in the recipe by 2 degrees F to prevent overcooking. Colorado State University provides a High Elevation Candy Making (Sugar Solution) Adjustment chart for various kinds of candy mixtures.

Find and Know Your Elevation

Elevation matters in all aspects of food preparation. It is especially important for the safety of home canned products beginning at elevations above 1,000 feet. Before beginning the canning process or making sugar concentrations, find your elevation using one of these sources to insure proper processing of canned products and prevent overcooking of jams and candies:

Visit a web page about your town or city.
Use an online tool such as What is my elevation?
Use a smartphone app such as My Elevation.
Refer to an elevation map for your state showing approximate elevations such as this one by Iowa State University Extension and Outreach from the Preserve the Taste of Summer series.

To learn more about elevation, watch this YouTube video by UNL Extension Food & Fitness.

To learn more about safe water-bath or pressure canning practices, watch these videos produced by South Dakota State University:

Marlene Geiger

I am a graduate of the University of Nebraska-Lincoln with a BS in Home Economics Education and Extension and from Colorado State University with a MS in Textiles and Clothing. I enjoy spending time with family and friends, gardening, quilting, cooking, sewing, and sharing knowledge and experience with others.

March 1, 2024

Equipment, Food Preparation, Food Preservation, Food Safety candy making, canning, Elevation, jam and jelly making

1 Comment

Start a Canning and Preserving Notebook/Journal

October 24, 2023 Marlene Geiger 1 Comment

With gardens and orchards coming to their seasonal ends, food preservation is wrapping up. Now is the time to make a note of it! Better yet, start a preserving notebook if you do not already have one to get ready and organized for coming seasons.

Cover of a preserving notebook — Cover of Preserving Notebook – Photo: mrgeiger

A few years ago, I had the brilliant idea to start a notebook of safe canning recipes so that I did not have to look them up or remember where they came from when I was ready to preserve. Since that time, that notebook has become my go-to for all things food preservation and includes recipes, tips, notes, answers to questions, quantities made and used, dates made or put into storage, new equipment to check out, and more–anything that I need to jog my memory. I only wish that I had started my notebook and journal many years ago; it would have saved me so much time, saved me from making mistakes, kept me organized, prevented food waste, and made sharing and preserving so much easier and more efficient. It would also be a wonderful history of my canning and preserving life.

The notebook, a 3-ring binder, started with recipes copied or printed from reliable sources for all of the usual things—tomatoes, green beans, fruit juice, strawberry jam, salsa, etc. As time has gone on, more recipes have been added, expanding the kinds of things preserved as well as helpful information including updated methods. Another valuable part of my notebook is the annual journal listing the foods preserved, how much, when, recipe, etc. At first, it was just a piece of notebook paper with columns. Since then I have made a page using Excel on my computer that can be printed each year and penciled in as preservation takes place.

The best time to start a notebook or journal is NOW while you may still have memories of what you did in the past season and prepare for a new canning or preserving season. Besides making preservation more efficient, it can also be a way to be creative making it your own like a scrapbook. If you are not crafty, there are ready-made and even handcrafted personalized canning and preserving journals available to purchase. Most of these are available on various online sites.

Preserve what you have learned or have done. Keep track of all your canning and preserving projects for future seasons and perhaps posterity! You’ll be glad you did!

Marlene Geiger

April 2, 2024

Adult Learning, Consumer Management, Food Preservation canning, history, notebook, preserving

1 Comment

Thickeners for Home Canning

August 16, 2022 Marlene Geiger 24 Comments

Home canned fruit pie fillings make it easy to prepare delicious pies and desserts all year long. Since 2015 the USDA and the National Center for Home Food Preservation has recommended Clearjel® (cook type, not instant) as the thickening agent for some home canned fruit pie fillings. There is not a safe substitute for Clearjel® when canning pie filling.

Two quart jars of canned apple pie filling.

Clearjel® is a flavorless, modified cornstarch that doesn’t break down through the canning and baking process. It can withstand a variety of pH levels and allows for adequate heat penetration during processing to render a shelf-safe product. Clearjel® differs from other thickeners such as regular cornstarch, flour, and tapioca which thicken with heat, become dense, clump, break down with additional cooking, and do not allow for adequate heat penetration during processing. Without heat penetrating throughout the jar, yeast, mold, or other harmful bacteria can form. Clearjel® only thickens a small amount with heat; thereby, reducing the density and heat penetration issues during processing. Heat is able to penetrate the contents of the jar completely and safely. The filling thickens in the jar after the jars are removed from the canner and the food cools. Clearjel® does not break down over multiple heatings as other thickeners might. In home-canned pie fillings, it easily survives the three heatings of preparation, processing, and eventual baking.

To use, follow directions in Fruit Pie Fillings for Home Canning by Washington State University. Care should be taken to not exceed the specified amount of thickener to avoid jelling, oozing*, or inadequate heat penetration.

The shelf-life of Clearjel® in canned foods is excellent. Canned products retain a smooth texture with no liquid separation, weeping, or curdling during storage. Like most home canned foods, pie fillings should be used within a year for best quality.

Clearjel® is not designed for freezing as it breaks down through freezing and thawing. Instant Clearjel® is freezer stable yet tolerates baking temperatures. It thickens without cooking and begins to swell as soon as it is added to liquid gradually increasing in thickness during heating. Although not modified food starches, arrowroot and tapioca starch can also be used to thicken products for freezing yielding satisfactory freeze-thaw results. Do not use Instant Clearjel® in canned pie fillings.

While Clearjel® is widely used commercially, its manufacturer, Ingredion, has not made it easily available to consumers. Therefore, it behooves one to think ahead. It is generally sold in bulk and is available only through a few supply outlets; it is not currently available in traditional grocery stores. Look for it at online sources, Amish groceries, or bakery supply stores. If Clearjel® is not available at the time of preserving, pie filling can be made without and thickened at the time of use with any suitable starch. There are about 3 cups of Clearjel® in a pound.

At the present time, the USDA, the National Center for Home Food Preservation, and most University Extensions, including Iowa State University Extension and Outreach and Minnesota Extension, stand by Clearjel® as the only recommended starch for four pie fillings– apple, blueberry, cherry, and peach pie fillings; there have been no broadening of recommendations from the USDA or NCHFP for other uses. However, some University Extensions have expanded the use of Clearjel® with tested canning applications or alternative products. Food scientists at Oregon State University Extension have added a Blackberry Pie Filling option to the list of approved USDA pie filling recipes by following the USDA cherry recipe with blackberry as a substitute. Washington State University Extension has added recipes for making jams with Clearjel®.

PermaFlo®, ThermFlo® and Thick Gel™ are commercial equivalents that have been accepted as alternatives for Clearjel® by some University Extensions. Penn State prefers ThermFlo® as an alternative for its “added advantage of holding up well during storage if canned goods are stored in a cold basement. This stability factor allows it to be used in frozen pie fillings.” ThermFlo® is also made by Ingredion. Utah State Extension recognizes Thick Gel™ as an alternative for Clearjel®. Thick Gel™ is made and marketed by Cornaby’s, a Utah based company, which sells directly to consumers. It advertises itself as gluten-free and non-GMO. (Per the Ingredion website, Clearjel® is also gluten-free.) PermaFlo® was not found to be mentioned by any particular University Extension; it is a product of Tate & Lyle International.

As always, to ensure a safe product, use a tested canning recipe without alteration and follow the latest guidelines; the National Center for Home Food Preservation, USDA Complete Guide to Home Canning, and So Easy to Preserve are trusted sources. If other recipes or products are used, check with the manufacturer or recipe source regarding use and product safety.

Marlene Geiger

April 2, 2024

Food Preservation canning, Clearjel, pie filling, Thickeners

24 Comments

Plum Preserves

September 5, 2013 Beth Marrs 2 Comments

I have been trying to recreate the Damson Plum Preserves from my childhood. When I spotted Italian Prune Plums in our local grocery store I knew I had to try them in jam. Using the recipe below, I prepared the jam and put it into my freezer for later use. I will be making this jam every year! Though I used this jam as a freezer recipe it can also be processed in a boiling water bath – 5 minutes for 1000 ft in elevation and under and 10 minutes for 1000 ft. in elevation and over.

Plum Preserves Yield: 8 cups

2 quarts chopped plums(about 4 pounds)
6 cups sugar
1 1/2 cups water
1/4 cup lemon juice

Combine all ingredients. Bring slowly to a boil, stirring occasionally until sugar dissolves. Cook rapidly to jelly point, about 20 minutes. Process in a boiling water bath.

Beth Marrs

I graduated from Iowa State University with a degree in Adult Home Economics Education. I love to cook and entertain and spend time with my family.

January 19, 2016

Food Preservation canning, jam, plums, preserves, recipe

2 Comments

Canning tomatoes

August 22, 2013 Liz Meimann 4 Comments

If you are starting to run out of room in the freezer you may want to think about canning some tomatoes this summer. Once you have acidified the tomatoes, it is safe to process them in a boiling water bath canner. You need 1 tablespoon of bottled lemon juice per pint and 2 tablespoons per quart of tomato product. These same amounts of acid are required regardless of the tomato product you are canning-unless you are making salsa. Salsas have different requirements and you should always use a tested recipe to make them.

There are several different methods you can use to can tomatoes once you have skinned them.

Crush and cook them tomatoes; this method will prevent separation in the finished product.
Leave the tomatoes whole or halve them and pack them in water.
Leave the tomatoes whole or halve them and pack them in tomato juice.
Pack whole tomatoes into a jar, pressing them until all the space between the tomatoes is filled with juice.

These methods have slightly different processing times and can be processed in either the boiling water bath canner or in a pressure canner. Remember that the tomatoes must be acidified to produce a safe product no matter which type of canner you choose.

We also have tested recipes available for stewed tomatoes, tomato juice, tomato sauce, tomato paste, tomato catsup, barbeque sauce, chili sauce, hot sauce, and spaghetti sauce.

Enjoy the taste of your garden tomatoes long into the winter.

Liz Meimann

I received both my undergraduate and graduate degrees in Food Science at Iowa State University. I love to quilt, sew, cook, and bake. I spent many years gardening, canning, and preserving food for my family when my children were at home.

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January 15, 2016

Food Preservation acidification, canning, salsa, tested recipes, tomatoes

4 Comments

Floating fruit

August 15, 2013 Beth Marrs

We have had several people ask about why the fruit that they are canning floats in the jars. Floating fruit doesn’t affect the taste or the safety of the fruit just the appearance. There are several reasons why this may happen.

To limit the floating fruit:

Can fruit using a hot pack where the fruit is heated before adding to the jar. This is especially true for peaches and pears.
Use light or medium syrup instead of heavy syrup.
Pack the fruit as closely as possible without crushing it in the jars. Heating drives the oxygen from the tissues of the fruit so if the jars are loosely packed the fruit will tend to float.
Be sure to use the correct time and processing method for the fruit you are preserving. Over processing destroys the cell structure and makes the fruit lighter.

If you have a question about processing times and methods for the fruit you want to preserve give us a call at AnswerLine!

Beth Marrs

I graduated from Iowa State University with a degree in Adult Home Economics Education. I love to cook and entertain and spend time with my family.

January 15, 2016

Food Preservation canning, floating fruit, preserving fruit

Canning Peaches

August 12, 2013 Liz Meimann 4 Comments

I grew up in St. Louis, MO during the 1960’s. St. Louis had a Farmer’s Market on the south side of town that my family visited during the growing season. The fruit I most enjoyed during those visits was peaches. When we got home from the market my father and I would stand at the kitchen sink eating peaches so juicy that their juices dripped down our arms and ran off our elbows. After we ate all the fresh peaches our stomachs would hold, my mother would can them. That taste of summer during the long, cold winter months was a real treat!

Selecting, Preparing and Canning Fruit

Peaches-Halved or Sliced

Quantity: An average of 17½ pounds is needed per canner load of 7 quarts; an average of 11 pounds is needed per canner load of 9 pints. A bushel weighs 48 pounds and yields 16 to 24 quarts – an average of 2½ pounds per quart.

Quality: Choose ripe, mature fruit of ideal quality for eating fresh or cooking.

Please read Using Pressure Canners and Using Boiling Water Canners before beginning. If this is your first time canning, it is recommended that you read Principles of Home Canning.

Procedure: Dip fruit in boiling water for 30 to 60 seconds until skins loosen. Dip quickly in cold water and slip off skins. Cut in half, remove pits and slice if desired. To prevent darkening, keep peeled fruit in ascorbic acid solution. Prepare and boil a very light, light, or medium syrup or pack peaches in water, apple juice, or white grape juice. Raw packs make poor quality peaches.

Hot pack – In a large saucepan place drained fruit in syrup, water, or juice and bring to boil. Fill jars with hot fruit and cooking liquid, leaving ½-inch headspace. Place halves in layers, cut side down.

Raw pack – Fill jars with raw fruit, cut side down, and add hot water, juice, or syrup, leaving ½-inch headspace.

Adjust lids and process.

Processing directions for canning peaches in a boiling-water canner are given in Table 1.

Processing directions for canning peaches in a dial- or weighted-gauge canner are given in Table 2 and Table 3.

Table 1. Recommended process time for Peaches, halved or sliced in a boiling-water canner.
–		Process Time at Altitudes of
Style of Pack	Jar Size	0 – 1,000 ft	1,001 – 3,000 ft	3,001 – 6,000 ft	Above 6,000 ft
Hot	Pints Quarts	20 min 25	25 30	30 35	35 40
Raw	Pints Quarts	25 30	30 35	35 40	40 45

Table 2. Process Times for Peaches (Halved or Sliced) in a Dial-Gauge Pressure Canner.
			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time (Min)	0 – 2,000 ft	2,001 – 4,000 ft	4,001 – 6,000 ft	6,001 – 8,000 ft
Hot and Raw	Pints or Quarts	10	6	7	8	9

Table 3. Process Times for Peaches (Halved or Sliced) in a Weighted-Gauge Pressure Canner.
			Canner Pressure (PSI) at Altitudes of
Style of Pack	Jar Size	Process Time (Min)	0 – 1,000 ft	Above 1,000 ft
Hot and Raw	Pints or Quarts	10	5	10

This document was adapted from the “Complete Guide to Home Canning,” Agriculture Information Bulletin No. 539, USDA, revised 2009. Reviewed November 2009.

Liz Meimann

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January 19, 2016

Food Preservation ascorbic acid, canning, fruit, peaches, syrups, tested recipe

4 Comments

Always use safe, tested recipes when canning salsa

August 8, 2013 Liz Meimann 2 Comments

Just about this time every summer we start getting calls about salsa. Salsa is one of those foods that brings out the creative side of people. It is not uncommon to get questions about how long to process the salsa recipe they just created, or the salsa recipe they got from a friend. Our answer is always the same. It is important to use a tested recipe when canning homemade salsa. The ratio of low acid vegetables (tomatoes, peppers, onion, and garlic) to acid (lemon juice, lime juice, or vinegar) has not been calculated in a non-tested recipe. Tested recipes contain enough acid to prevent the growth of the botulism bacteria and provide a safe product that can be enjoyed straight from the canning jar. Non-tested recipes may be safe but there is no real way to know that in advance of eating the salsa. The risk of botulism poisoning is not known but the result of the illness can be death or prolonged illness. NO salsa is worth that risk.

You can safely freeze any salsa recipe you can devise so we advise callers to freeze salsa recipes of their own creation instead of canning. We have a number of tested salsa recipes and we are happy to share them with you. Contact us at AnswerLine for these recipes.

Liz Meimann

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January 15, 2016

Food Preservation, Food Safety canning, salsa, tested recipes, tomatoes

2 Comments

Salsa

August 5, 2013 Liz Meimann

This time of year it seems that everyone has a favorite recipe for salsa. Salsa is a fun and easy product to make. Salsas are combinations of acidic and low acid vegetables. The onions, peppers, and garlic are low acid foods. Producing a safe product that can be home canned means you must add enough of the right type of acid to prevent the growth of botulism bacteria. The best way to ensure a safe salsa is to carefully follow a tested recipe. You can find tested recipes in several places. The USDA canning guide, the National Center for Home Food Preservation, and Extension publications like Preserve the Taste of Summer.

Here are a few helpful tips to remember:

Use high quality tomatoes, peppers, onions, and garlic. Canning won’t improve the quality of the ingredients.
Remember not to increase the total volume of peppers. You can substitute one variety of pepper for another—to make a hotter or milder salsa.
Use the acid listed in the recipe; bottled lemon juice, vinegar with 5% acidity, or lime juice.
Spices may be adjusted to taste flavoring. It is really the only safe ingredient to change in a tested recipe.
Using a tested recipe allows you to process a safe salsa in a boiling water bath canner. If you choose to use a recipe of your own, remember that you can safely freeze that salsa, but you cannot home can it.
Don’t thicken salsa before canning. As you open jars of your salsa, you can thicken it or pour off excess liquid.

Liz Meimann

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January 15, 2016

Food Preservation canning, salsa, tested recipes, tomatoes

Pickled beets

July 29, 2013 Liz Meimann

I never grown beets in my garden but I’ve always enjoyed them. It’s too late to plant any this summer but I think I’ll try to find some room for them in my garden next summer.

Canning pickled beets:

Choose either small baby beets, which can be pickled whole or use beets no larger than 2 ½ inch in diameter. These will make the best pickled beets.

Beets must be cooked before pickling. Trim the beet top leaving one inch of stem and the root; this will prevent bleeding and maintain a nice bright red beet color. Cook the beets in boiling water until tender. Remember to drain the beets and toss the cooking water. After cooling beets, trim the stems, remove the roots, and slip the skins. Baby beets can be pickled whole; larger beets should be sliced into uniform slices. Visit the National Center for Home Food Preservation for the rest of the recipe.

Since these beets are pickled, they can safely be processed in a boiling water bath canner.

Process times at Altitudes of
Style of pack	Jar size	0-1000 ft	1001-3000 ft	3001-6000 ft	Above 6000 ft
Hot	Pints or Quarts	30 min	35 min	40 min	45 min

Here is a link to other tested pickled vegetable recipes from the National Center for Home Food Preservation.

Liz Meimann

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January 15, 2016

Food Preservation beets, canning, pickling, processing times, vegetable pickles

Tag: canning

Elevation? Does It Matter?

Marlene Geiger

Start a Canning and Preserving Notebook/Journal

Marlene Geiger

Thickeners for Home Canning

Marlene Geiger

Plum Preserves

Beth Marrs

Canning tomatoes

Liz Meimann

Floating fruit

Beth Marrs

Canning Peaches

Liz Meimann

Always use safe, tested recipes when canning salsa

Liz Meimann

Salsa

Liz Meimann

Pickled beets

Liz Meimann

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