Home canning onion jam
I feel like I do when I go shopping for a dress and have a specific dress in mind with looking for a recipe for caramelized onion jam.
I know what I want in the end and I want to home can it so it will be shelf stable. I am a chef and Dietitian so I am super aware of the food safety concerns with home canning a low-acid food like onions. I am looking for a "rule-of-thumb" ratio of onions to acic (e.g. total amount of vinegar, lemon juice, etc) to be able to make the jam safe and shelf stable by boiling method (not pressure cooker method).
Any advice or websites out there that you all are aware of that can give me this information?
Thanks in advance,
Here's my recipe, with accurate proportions:
Spring onion and garlic jam
Yields 1 pint
9 oz peeled spring onions, shallots, and garlic with only a small part of their green stems
1 oz butter
7 oz Riesling
2 tsp lemon juice
0.25 oz powdered pectin
5.5 oz sugar
Slice the onions, shallots, and garlic very finely, then sauté with the butter in a small pan over low heat. Cook until translucent, stirring frequently — do not allow to brown, or the jam will have a tough texture.
Add the wine and lemon juice, sprinkle the pectin, and bring to a rolling boil, stirring constantly. Mix in the sugar progressively, bring back to a boil, and boil for 1 minute. Let cool for 5 minutes.
Transfer to a sterilized pint jar, seal, and process in a 200 F water bath for 15 minutes.
Let cool for about 30 minutes, then refrigerate.
I've been doing a lot of reading about canning and acids, etc. I don't have a recipe for you, but jam is less prone to botulism due to the low water content. I found this to be very educational, but doesn't address your question exactly.
Another excellent source: http://nchfp.uga.edu/how/can_07/prep_... Unfortunately, the only statement I see is that if the jam has too little acid it will be watery.
According to The Jam Lady Cookbook by Beverly Ellen schoonmaker Alfeld, food with a Ph less than 4.2 or more than 4.6 should not be canned. She states that foods with a Ph of 4.2 or lower are classified as high-acid canning, while foods with a ph of 4.6 or higher are classified as low acid canning. She suggests using a Ph meter to measure the prepared food before canning and after opening. According to the chart in the book, red onions have a Ph of 5.30-5.80, white onions are 5.40-5.80 and yellow are 5.32-5.60. She lists a Pear and Red Onion Jelly that is not a canning recipe, but refrigerated. Apparently there are other things to consider when trying to estimate Ph, like buffering capacites and molarity. I guess this means mixing high and low acid foods doesn't necessarily mean the finished product is in the middle. She doesn't give ratios of high and low acid foods. In the end, she says to use the Ph meter. You can also try freezer jam instead.
Your idea sounds yummy!