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Tomatoes & Acidity (LONG)

Posted by vtguitargirl Z4/5 VT (My Page) on
Tue, Aug 14, 07 at 16:45

Sorry folks, but this one is long!

An experienced local gardener who also cans her tomatoes told me that many of the newer tomato varieties are less acidic than the old varieties. Yet I remember reading on this forum that tomato varieties have more or less the same acidity.

Recently I read this from a tomato recipe forum:
A Note On Canning Safety: Tomatoes, because of their acid content, have in past years been considered safe to can in a boiling-water bath. However, in recent years hybridizers have developed "sub-acid" varieties that may be on the borderline of acid content where the safe canning of tomatoes or their juice is concerned. to be on the safe side, taste the juice before canning it. If it lacks tartness, be sure to add enough lemon juice to re-create the characteristic pleasant tomato sharpness.

So, what's the deal? Has tomato acidity and/or flavor changed over the years? Do people add lemon juice to their canning recipe now just to be on the safe side? Were folks risking their health canning tomatoes without lemon juice years ago?

Follow-Up Postings:

RE: Tomatoes & Acidity (LONG)

Hi vtguitargirl,

Tomato acidity can vary with variety, soil, and growing conditions, but the vast vast majority are below the 4.6 pH level considered safe for BWB canning. The experts and/or those with liability for their statements recommend adding lemon juice or vinegar just to be absolutely sure.

For what it's worth, I have put up around 1,000 pints of salsa over the past 30+ years using a boiling water bath and no acid boosters as I do not want the taste of lemon or vinegar in my salsa. And this recipe contains a fair amount of low acid veggies such as onions, hot peppers, and garlic. I have grown dozens of tomato varieties over the period and never had a spoiled jar of any kind. Of course I sterilized everything that came in contact with the food, and processed for 45 minutes.

I believe most experts, which I am not, would advise adding an acid booster, but they would also say to stick with proven recipes, and I would say mine is proven after all these years. Personally I find the risk acceptably low but you may not.

Two years ago I bought an All American pressure canner to speed the processing, so now I process all jars of salsa at 10 pounds of pressure for 15 minutes. To my knowledge, acid boosters are not needed with pressure processing.


RE: Tomatoes & Acidity (LONG)

Has tomato acidity and/or flavor changed over the years?

Some of the "new" hybrid taste less acidic but based on all my reading that is supposedly due to the increased sugar content rather than actual lower acidity.

But I do agree with Tom that ph can differ because of all the factors he listed. So yes, for that reason, I add the 1-2 T of lemon juice to any of my canned tomato products that will be BWB but not to those that require pressure cooking. Personally I don't find that small amount alters the taste in any way.

Found this list of the less acidic varieties and linked to the Univ. MN article if you are interested.

"Researchers at USDA and at the University of Minnesota have found that most underripe to ripe, cooked tomatoes have a pH below 4.6. Unfortunately, a few varieties may have a pH above or close to 4.6. These include Ace, Ace 55VF, Beefmaster Hybrid, Big Early Hybrid, Big Girl, Big Set, Burpee VF Hybrid, Cal Ace, Delicious, Fireball, Garden State, Royal Chico, and San Marzano. Some of these are grown for commercial purposes and are not found in home gardens. However, safely canning these varieties requires additional acid for water bath processing or a pressure canning process similar to low acid vegetables."

Home Canning Tomatoes


RE: Tomatoes & Acidity (LONG)

I use citric acid which affects the flavor even less. Available with canning supplies at Agway. I've made it to old age by being safe rather than sorry!

RE: Tomatoes & Acidity (LONG)

I asked my DH, who does all our canning, to start canning with a pressure canner, but he says he would rather do the hot-pack method. He is very very careful to make sure everything is well-sanitized and the tomatoes are boiling when he puts them into the hot jars. And we do re-boil the contents when we open them, so hopefully we will be OK.

RE: Tomatoes & Acidity (LONG)

This is a big pic from an Excel file but there's a lot of popular heirloom varieties on the chart, as well as some lesser knowns & OP's, see the last column showing pH.

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