Monday, September 10, 2012

Canning Tomato Salsa

Tomatoes, tomatoes and more tomatoes!  It's definitely that time of year.

In addition to BLT's, tomato soup, fresh salsa, and bruschetta, I've used our tomatoes for frozen tomato soup stock (juice), canned diced tomatoes, and frozen tomatoes.  But my favourite tomato preserve is tomato salsa.  Opening one of those jars in the middle of winter is like a little taste of heaven.

I'm not going to lie - canning salsa (or tomatoes for that matter) is time consuming work.  The issue with canning tomatoes is that the level of acid in them varies and often it is too low in order for them to be processed like other fruits which are typically considered high acid foods.  And, with salsa, we often add more low aid veggies like onions, peppers and herbs.  High moisture, low acid, low salt and low oxygen environments are ideal for the growth of Clostridium botulinum, the bacteria that causes botulism (read more here). 

As a result, to can tomatoes or salsa safely, we need to ensure that there is enough acid in our canned goods to make conditions unsatisfactory for Clostridium botulinum, that we're vigilant about following safe water bath canning procedures and that we process them for the recommended time.  When canning tomatoes, the recommendation for acid is adding 2 tbsp of lemon juice or vinegar (5% acid) for every litre or quart jar or 1 tbsp for every 500ml or pint sized jar.  When canning salsa follow a recipe that comes from a credible source where the proportions of acid to non-acid foods have been measured and tested.  I turn to the National Centre for Home Food Preservation.

Here's a step by step look at how I made my salsa.
score washed tomatoes with an x on the bottom
place in boiling water for 60 seconds
remove from boiling water and immediately put in ice water for peel to come off easily
peel tomatoes
for thick salsa, remove the seeds and liquid from the tomatoes
chop and mix all ingredients in a large pot
simmer for 30 minutes
fill hot jars leaving 1/2 inch headspace, seal and process pint (500ml) jars for 15 minutes

Remove from canner and allow to cool on counter for 24 hours.  Check seal.  Enjoy any that did not seal properly right away and tuck the rest away for a delicious winter treat.
Of course, you can always freeze your tomatoes and avoid all this trouble.  But, if you're freezer is full - go for it!

No comments: