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Foam in Home Jam Making - What It Is and What To Do About It!

What To Do About the Foam on Your Jam!

Your are happily making jam, following the direction in a book or box of pectin... until it says "skim the foam, or add 1 teaspoon of butter to prevent foaming".  Foam?  Foaming?  What is it?  Does your jam have rabies?

Nope, the foam is just the result of bubbles from the boiling jam coming up through the viscous jam.  Just like a child blowing bubbles, the boiling jam produces bubbles.

Why remove it?

Well, it just doesn't taste very good.  It doesn't taste bad, but it is not the consistency most people like in jam. It certainly won't hurt you, though. It might somewhat shorten the storage life of the jam. According to Janet Hackert, Nutrition Specialist, Northwest Region at the University of Missouri Extension:

Foam contains a lot of air. In canning, the jars are not filled to the top of the jar. This gap between the lid and the food is called head space and it gives the canned food room to "breathe." The food can expand during processing and form a vacuum as the jar cools. Foam in a jar of jam increases the head space. According to the Food Safety Information Service, this is not a problem if the jam is stored in a cool place and is eaten relatively soon. The extra head space does increase the chance of the jam molding after prolonged storage though.

What can I do about the foam

Besides making a B-grade horror movies with it, You can either prevent it or remove it.

Prevent it

1 teaspoon of butter, margarine or vegetable oil, added before you heat the mixture will almost eliminate it. On the downside, some food scientists worry that the small amount of butter could cause the batch to spoil sooner. I suspect this particular group of scientists probably still live at home...

Remove it

Skimming the fom off the jamWhen I forget to add the butter (about 50% of the time), I just wait till I remove the jam from the heat, let it sit for a minute or two and then skim the foam off with a ladle.

I save the foam in a microwavable container.  See below for why!

What can I do with the foam?

When I am done making jam for the day, I usually have about 1 cup of congealed foam.  Looks a lot like a healthy lung.  That's not very appealing to most people, so....

Just pop it into a microwave for 30 to 60 seconds or so on high.  Be sure to watch it the entire time, or it may boil over.  You want to get it hot again and to boil up a bit.

 Once you remove it and it cools, it will look, act and taste like regular jam again!  Rather than attempting to put this back into a batch for canning, this is the jam I stick in the fridge to use fresh!

Blake's Easy and Illustrated Jam and Ice Cream Directions

I've got some other pages for specific types of jam, too:

Jams and jellies:

Ice Cream, Gelato and Sorbets with your own fruit


Summary - Typical Cost of Making Homemade Jam - makes 8 jars, 8 oz each**

Item Quantity Cost in 2024 Source Subtotal
Berries (strawberries) 1 gallon $8.00/gallon Pick your own $8.00
Canning jars (8 oz size), includes lids and rings 18 jars $11/dozen 8 oz jars
or $0.92/jar
Grocery stores, like Public, Kroger, Safeway and sometimes, Big Lots, local hardware stores and big box stores $10.00
Sugar 4 cups $2.00 Grocery stores, like Public, Kroger, Safeway and sometimes, Big Lots, local hardware stores and big box stores $2.00
Pectin (low sugar, dry) 1 and a third boxes * $2.00 per box Grocery stores, like Public, Kroger, Safeway and sometimes, Big Lots, local hardware stores and big box stores $2.70
Total $22.70 total
or about $1.25 per jar
* pectin use varies - blackberry jam needs very little, raspberry a little more, strawberry the most.

** - This assumes you already have the pots, pans, ladles,, and reusable equipment. Note that you can reuse the jars and reduce the cost further; just buy new lids (the rings are reusable, but the flat lids are not)!

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FAQs - Answers to Common Questions

Canning Books, Supplies and Accessories

These are my favorite essential canning tools, books and supplies. I've been using many of these for over 50 years of canning! The ones below on this page are just the sampling of. my preferred tools. but you can find much more detailed and extensive selections on the pages that are linked below.

The All New Ball Book Of Canning And Preserving: Over 350 of the Best Canned, Jammed, Pickled, and Preserved Recipes Paperback

This is THE book on canning! My grandmother used this book when I was a child.; It tells you in simple instructions how to can almost anything; complete with recipes for jam, jellies, pickles, sauces, canning vegetables, meats, etc.

If it can be canned, this book likely tells you how! Click on the link below for more information and / or to buy (no obligation to buy)The New Ball Blue Book of Canning and Preserving

Canning and Preserving for Dummies by Karen Ward

This is another popular canning book. Click here for more information, reviews, prices for Canning and Preserving For Dummies

Of course, you do not need to buy ANY canning book as I have about 500 canning, freezing, dehydrating and more recipes all online for free, just see Easy Home Canning Directions.

Home Canning Kits

I have several canners, and my favorite is the stainless steel one at right. It is easy to clean and seems like it will last forever. Mine is 10 years old and looks like new.

The black ones are the same type of standard canner that my grandmother used to make everything from applesauce to jams and jellies to tomato and spaghetti sauce.

This complete kit includes everything you need and lasts for years: the canner, jar rack, Jar grabber tongs, lid lifting wand, a plastic funnel, labels, bubble freer,  It's much cheaper than buying the items separately. It's only missing the bible of canning, the Ball Blue Book.

You will never need anything else except jars & lids (and the jars are reusable)! 

The complete list of canners is on these pages:


Pressure Canners

If you plan on canning non-acidic foods and low acid foods that are not pickled - this means: meats, seafood, soups, green beans corn, most vegetables, etc., then you ABSOLUTELY must use a Pressure Canner.

Of course, you can use a pressure canner as a water bath canner as well - just don't seal it up, so it does not pressurize. This means a Pressure Canner is a 2-in-1 device. With it, you can can almost ANYTHING.

There are also other supplies, accessories, tools and more canners, of different styles, makes and prices, click here!

Basic Canning Accessories

From left to right:

  1. Jar lifting tongs to pick up hot jars
  2. Lid lifter - to remove lids from the pot of boiling water (sterilizing )
  3. Lids- disposable - you may only use them once
  4. Ring - holds the lids on the jar until after the jars cool - then you remove them, save them and reuse them
  5. Canning Jar funnel - to fill the jars

FREE Illustrated Canning, Freezing, Jam Instructions and Recipes

Don't spend money on books. that you don't need to. Almost everything you can find in some book sold online or in a store is on my website here for free. Start with theEasy Home Canning Directions below. That is a master list of canning directions which are all based upon the Ball Bblue book, the National Center for Home Food Preservation and other reputable lab tested recipes. Almost every recipe I present in addition to being lab tested com. is in a step by step format with photos for each step and complete. explanations. that tell you how to do it, where to get the supplies and pretty much everything you need to know. In addition, there almost always in a PDF format so you can print them out and use them while you cook.

[ Easy Home Canning Directions]

[FAQs - Answers to common questions and problems]

[Recommended books about home canning, jam making, drying and preserving!]

[Free canning publications to download and print]