Leena Cooks and Cans: Caramelized Onion Jam Update

By on Nov 17, 2014 in Canning, Jam, Leena Cooks, pH of food, Savory | 0 comments

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My caramelized onion jam: still safe to water bath can, still freaking delicious.

My caramelized onion jam: still safe to water bath can, still freaking delicious.

My caramelized onion jam canning post has been the MOST commented on post on my entire site—even during times when I have had to take a break from writing. Many of you have had questions about the details (the weight of the onions, do you need to pH test to can, etc). Some of you have said it is impossible for this to be safe to waterbath can for various reasons (too much oil, disagreement on the proper pH level for water bath canning food, etc).

Since it has been three years since I posted the recipe, I decided it was a good time to write an update and combine my three previous posts on this topic (this one, this one and this one) into one. I made a small batch, tested the pH, and have made the recipe more detailed. Check it out!

So first off, there has been one MAJOR change since the last time I posted about this recipe.

My daughter.

My daughter: then and now. God bless potty training.

My daughter: then and now. God bless potty training.

She still doesn’t nap, but she also doesn’t rely on me to do everything for her anymore, which has been been awesome for my canning game. I just bust out the iPad for when I have to transfer the food into hot jars and the jars into the water bath, and it’s almost like I am kid-free again. ALMOST.

Back to the recipe: I’m going to put the new details both here and in the actual recipe, so whichever you read, you will know of the changes. I used four pounds of medium diced onions, which is usually somewhere between four and half and five pounds of whole onions. That means you should have four pound of onions once you have peeled and chopped them, not before. You definitely need a scale to make sure you have the right weight. Any deviation means it will not have the same pH.

Makes me hungry just looking at it.

Makes me hungry just looking at it.

When caramelizing my onions for the jam, I prefer to do it mostly in the oven, which is helpful for making double and triple batches of this recipe, and also leads to less time standing at the stove, stirring the onions until my arms fall off. I basically follow the method outlined in this recipe, which originates from America’s Test Kitchen, with just a few changes.

First, I switched the butter for olive oil and upped it to match the same amount as I do in my caramelized onion jam recipe when doing it on the stove, 4 tablespoons. I take one tablespoon and brush it on the insides and bottom of a heavy, large pot (my 8qt Le Creuset works nicely). Then when I add the chopped onions, I toss them in the remaining three tablespoons of oil in the pot. Whether you decide to caramelize your onions in the oven or on the stove top, DO NOT use more than 4 tablespoons of oil. Anymore and the pH of the recipe will change, making it questionably safe.

This recipe yields 1 pint and 1 half pint, or 6 quarter pints.

This recipe yields 1 pint and 1 half pint, or 6 quarter pints.

I also cut out steps 4 and 5. Step 4 calls for adding water to the onions and letting it evaporate until a brown crust forms, and I stopped doing this because the damn brown crust adheres to my Le Creuset pan something fierce and takes MANY scrubbings to remove. Plus, as you can see, my onions are still really caramelized without that step. Step 5 calls for adding balsamic vinegar and letting the onions absorb them, but since I am adding vinegar later while making the jam, I left it out.

Then I make the jam as the recipe says, and I let it cook down for around 10-15 minutes. When the jam starts to get thicker, I take it off the heat, and test a small batch for gel by putting a spoonful on a plate that was in the freezer for at least ten minutes. I put the plate back in the freezer with the jam on it, set a two minute timer, and then take the plate out and hold it on it’s side to see how much the jam moves around. If it slides around a lot, I put the pot back on the stove and cook it a little longer to try and get a stronger gel. If it doesn’t move, or moves slowly, then the gel is perfect and it is ready to can.

My pH meter and testing solutions: three and half years and still going strong.

My pH meter and testing solutions: three and half years and still going strong.

At this point, the jam is ready to be put into hot, sterilized jars and canned in a water bath (10 minutes for a quarter pint, 15 minutes for a half pint, 20 minutes for a pint). After canning, I busted out my trusty pH meter (purchased here). Back in 2011 when I first posted this recipe, I could not find a canning book that spoke about testing pH or creating your own canning recipes. Little did I know that in 2012, just a year later, the cookbook Preservation Kitchen by chef Paul Virant was published doing just that! He recommends buying a pH meter to test anything you plan on canning, and testing the jar after it has been canned. Anything that is 4.6 and above must be pressure canned, while anything 4.5 or lower is safe to water bath can.

So using his suggestions and this document that I used back in 2011, I tested the pH of my jam. Here are the steps I followed:

    1. Determine food type and prep food accordingly: homogenous (uniform consistency like salad dressing), liquid/solid mixtures (salsa, pickles), semi-solid foods (Puddings, jams, etc.), oily foods.
    2. My food was considered semi-solid, so I pureed it to a uniform paste. If liquid is needed to blend, you are supposed to use 20 parts distilled water to 100 parts food. Distilled water can be bought at a store like Walgreens or CVS, basically a store with a pharmacy. I decided that 100 parts food = 50 ml jam, 20 parts liquid= 10 ml distilled water. I ended up using 200 ml jam and 40 ml distilled water for the finished uniform paste. Note if your food is not semi-solid, you will need to consult this article to determine how to prep your food.
      200 ml of jam plus 40 ml of distilled water.

      200 ml of jam plus 40 ml of distilled water.

      My pureed jam split into two testing portions.

      My pureed jam split into two testing portions.

      3. Calibrate meter with buffer solutions according to instructions provided.

      I calibrated my pH meter with two different solutions: pH 4.01 and pH 7.01.

      I calibrated my pH meter with two different solutions: pH 4.01 and pH 7.01.

      4. Rinse sensing probe with distilled water and blot (do not rub) with lint-free tissue paper (I used paper towels).Submerge probe in sample, and after allowing one minute for meter to stabilize, record pH. (Note- my meter has a stability indicator, which helps promote a properly taken sample.)

      Testing my jam's pH.

      Testing my jam’s pH.

5. Rinse probe, blot dry (do not rub!), and test again with a new sample. Two pHs should agree within the accuracy limits of the meter.

6. Rinse probe in distilled water, blot dry, apply a few drops of storage solution, and store meter.

If you can read the pH meter in the above photo, you will see it says 3.98 pH. I received that exact measurement for both samples I tested with my meter, and since it is under 4.6 (well under), my jam is perfectly safe to water bath can if you follow my instructions exactly. Please note that when I originally tested the recipe in 2011, it was 4.07 pH.

So there you have it! Let me say it again, for those who need a reminder: this jam is safe to water bath can if you FOLLOW MY INSTRUCTIONS EXACTLY. You do not need to test the pH of this jam before canning, unless you mess with the acid in the recipe. You can add different herbs or spices without affecting the pH. According to this helpful post from Food in Jars, I would not mess with the sugar amount either, because I want my jam to have the longest shelf life possible and I want it to gel properly. You can change it, if you so wish, just don’t expect it to gel the same or last as long.

If after all of this, you still think this is an unsafe canning recipe, feel free to not make it, make it and just keep in the fridge or bitch about it in the comments below. It won’t hurt my feelings or make me change anything, mind you. But it might make you feel better 🙂

And now, the recipe:


: Leena’s Updated Caramelized Onion Jam

: A delicious sweet and savory jam that is perfect with cheese, burgers, soups, whatever you like! This recipe was inspired by this one on the blog Market Life. This recipe has been tested for pH and is safe to water bath can.

  • 4 tablespoons olive oil
  • 4 pounds of onion, large diced (measure weight after cutting)
  • 2/3 cup sugar
  • 1/3 cup balsamic vinegar (not the aged sweet stuff)
  • 1/2 cup brandy
  • 1/3 cup honey
  • 1 teaspoon salt
  • 1/2 teaspoon ground pepper

  1. Preheat oven to 400 degrees F, adjust rack to the lower middle position. Brush the inside of pot with 1 tablespoon of olive oil. Add onions, salt and remaining 3 tablespoons of olive oil, toss to coat, cover with lid and place in oven for one hour.
  2. Remove pot and stir onions, scraping the bottom and sides of the pot. Return pot to oven with lid slightly ajar for 1 ¾ hours. Remove pot after one hour to stir onions and scrap bottom and sides of pot again.
  3. After 1 and ¾ hours, remove pot from oven, remove lid and place pot on medium-high heat. Cook onions for 15-20 minutes, stirring frequently until liquid evaporates and onions brown. (You can also caramelize the onions on the stove top with the same amount of oil, but it will take much more active stirring time).
  4. Add remaining ingredients and simmer on low stirring occasionally until the jam reaches the gel point, around 10-15 minutes. To test jam, place a small plate in the freezer for at least 10 minutes. When jam starts to get thick, remove from heat and spoon a bit onto the frozen plate, and place back in freezer for 2 minutes. If the jam barely moves and looks like a proper jam, it is done. If the jam pools juice, looks loose or slides around quickly on the plate, place pot back on stove until thicker and test again.
  5. Pour hot jam into clean hot quarter pint jars and boil in a water bath for 10 min (15 minutes for half pint jars, 20 minutes for pint jars). Let cool and store in a dark place. Refrigerate any excess. Yields 1 pint and 1 half pint.
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