Acidity and canning tomatoes
When hot water bath canning,
it's important to pay attention to
everything that goes in the jar. Sweeteners like honey and sugar
can be added with impunity, but including basil and onions in a tomato
sauce will raise the pH so much that you'd have to pressure can.
To stay on the safe side, look for proven recipes or simply can pure
fruits or tomatoes.
While I'm on the topic
of acidity, I should mention that the acidity
levels of tomatoes may sometimes be too low for hot water bath canning
unless you add a bit of bottled (not fresh) lemon juice or citric
acid. The magic cutoff point is 4.6 --- tomatoes with a pH at or
above this pH are not safe to hot water bath can on their own.
Proven tomatoes that definitely need lemon juice added include:
Depending on who you talk to,
San Marzano tomatoes may or may not be safe.
Varieties that
definitely have a pH low enough to allow you to hot
water bath can them without adding any lemon juice or citric acid
include:
However, to make the decision
even more complex, a high acid tomato variety may
produce low acid tomatoes if the fruits are overripe, bruised, cracked,
affected by blossom end rot, or nibbled by insects. In addition,
tomatoes ripened off the vine, in the fall when days are shorter, in
the
shade, or on dead vines can all have a pH too high to allow hot water
bath canning without added lemon juice. To play it safe, you
might as well add the lemon juice recommended in most modern recipes (2
tablespoons per quart of crushed tomatoes.)
To read more, check out Weekend
Homesteader: September
on Amazon (or email anna@kitenet.net and ask for your free pdf
copy.) Thank you to everyone who has already given the ebook a
try, and I would
be eternally grateful to anyone who takes the time to leave a review!
Or explore more posts by date or by subject.
About us: Anna Hess and Mark Hamilton spent over a decade living self-sufficiently in the mountains of Virginia before moving north to start over from scratch in the foothills of Ohio. They've experimented with permaculture, no-till gardening, trailersteading, home-based microbusinesses and much more, writing about their adventures in both blogs and books.
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Please forgive me, but I'm confused. I honestly know nothing about canning (though I'd like to learn), but your comment has me confused...
"While I'm on the topic of acidity, I should mention that the acidity levels of tomatoes may sometimes be too high for hot water bath canning unless you add a bit of bottled (not fresh) lemon juice or citric acid."
So, you cure the problem on high acidity in tomatoes for canning by.... adding more acid?