Wednesday, May 27, 2015

Foam and Two Types of Strawberry Jam

It is nearing the end of strawberry season here, and we picked up what we will probably be our last berries on Monday.  We have been getting a gallon or so a week to eat fresh and to make jam.  We also pureed a gallon and a half and made fruit leather in my new dehydrator (more on that later).  

When it comes to strawberry jam, I am a bit of a purist.  I like flavors in other jams like cardamom pear, gingered peach, and apple pie jam, but when it comes to strawberry I just want to taste strawberry.  I have gone the strawberry vanilla jam route without added pectin before, and even though it was good, the longer cooked jam and the vanilla took away some of the fresh taste that I love about strawberry jam.  So, I go the purchased pectin, classic recipe route when it comes to strawberry, and I am perfectly happy with that.   Over the years I have learned to preserve what we like best and what we will eat because ultimately (even though it may be fun), that's the point.  

I did decide to make some strawberry freezer jam this year though.  Freezer jam is not cooked, and therefore, it retains all of its bright, fresh flavor.  I froze the jam in pint containers, and it is delicious.  I wish I had added a little more pectin though because my berries were pretty ripe that day, and they prevented my freezer jam from setting up as much as I would have liked.  It is still spreadable, but could have been a little thicker.  I am thinking it will be just as delicious over yogurt as it will be on toast.  

All in all I put up 11 half-pints of canned strawberry jam and 5 pints of strawberry freezer jam.  

While I am posting about strawberry jam, I wanted to address the foam on jam issue.  If you have ever made cooked jam, you have most likely experienced a thick layer of foam on top as the jam cooks.  The directions in recipes will tell you that you can prevent some of this foam from forming by adding a little butter to the jam as it cooks.  I never do this, but that leaves me with foam to skim off.  

Foam on jam just after removing the pot from the heat

There are several reasons you want to skim the foam from jam, and even though I know some people who don't bother, I think good jam making practice says otherwise. First of all, as the jam cooks and air bubbles up forming the foam on top, the foam takes on a different appearance, consistency, and texture from the rest of the jam.  It is still tasty, but it is light and airy, not like jam.  It creates color variations in the finished jam if added in, and you will be able to visibly tell that you left it in.  This may not matter so much if you are just using the jam yourself, but if you plan to give it as a gift, enter it in a fair, etc. it will just be better aesthetically without it.  

Second, canning experts like those at the Missouri Cooperative Extension bring up a potential safety reason to remove foam.  They say that since the foam is made mostly of air, if you add the foam into the jar you are essentially increasing the head space in the jar.  This could lead to improper seals or jams that mold more easily.  While I don't think you will ever get sick from jam with foam (unless you eat visibly moldy jam), it could mean that your jam will not last as long, and let's face it, no one wants that.  So, when faced with foam, remove it by skimming a large, clean spoon lightly along the surface of the jam once the heat is removed.  Place the foam in a bowl and repeat until most of the foam has been removed.  The foam can then be eaten on toast or refrigerated for a few days while the rest of the jam is canned. 

Foam on jam after sitting for a minute or so-  you can see the difference in color between the lighter red foam and darker red jam and berries. 

I personally find that strawberry jam produces more foam than most other types of jam.  I'm not sure why this is the case, but I find I do more skimming with strawberry than any other.  If you make freezer jam, you may see a little foam at first (like in my pictures at the top), but that foam is different from foam on cooked jam. It will dissipate as the jam sets over that 30 minute period.   

Strawberry season is such a fleeting season here.  We look forward to it all year, and it is gone before we know it.  Preserving some in the form of jams, leathers, and even freezing them ensures we have the taste of strawberries year round, and for that, and I am grateful.  

picture from previous 2013 post on Strawberry Jam

For the canned Strawberry Jam recipe and directions, visit my page from a few years ago.  I use the same one.  I did, however, make 11 jars this year, so I adjusted my ingredients for a 10 jar batch (you don't want to do more than this at one time as it can prevent the jam from setting up).  If you wish to make 10 jars, follow the same procedures as on my previous post, but use the following quantities instead.  For 10 jars, you will use 6 2/3 cups crushed strawberries, 7 1/2 tablespoons pectin, and 8 1/3 cups sugar.  

Strawberry Freezer Jam- makes 6 half-pints (or 3 pints)

5 cups crushed strawberries
2 cups sugar
6 Tbsp Instant Pectin (for freezer jam)

In a large bowl, stir sugar and pectin together.  Add crushed strawberries and stir 3 minutes.  Ladle into freezer containers and allow to sit at room temperature 30 minutes.  Freeze or enjoy fresh.   


  1. Hum...I wonder where you are....strawberry season lasts a long time here in SF. As for the foam, I always put a bit of butter in the jam and that really helps. I skim off the foam i do get but it isn't a loy. Your jam jars look beautiful and I know you will be enjoying it when it is dark and cold!

  2. Pamela, I am in the Piedmont region of NC. Our strawberry season (at least where I am) started early April and runs into the very beginning of June, but after that, it is usually difficult to get them locally. We are getting ready to move into blueberries and blackberries.

    As for the butter, I always tell myself I'm going to add it when I make strawberry jam, and I never do for some reason. I need to do it, though, because it does make it a little easier.

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  5. Thank you for your great article and the explanation about the foam you get on the top of the jam when its cooking. I've always been unsure what to do about it, so I'll just skim it off in future. I didn't know you got even more foam with strawberry jam so I'll make sure I'm ready for it!

    Faith Thomas @ The Berry Farm