nope, if they're pressured canned the high temp takes care of the botulism risk

Ball's directions follow those of the USDA/National Center for Home Food preservation (note the third paragraph:

"Acidification: To ensure safe acidity in whole, crushed, or juiced tomatoes, add two tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, use one tablespoon bottled lemon juice or 1/4 teaspoon citric acid. Acid can be added directly to the jars before filling with product. Add sugar to offset acid taste, if desired. Four tablespoons of a 5 percent acidity vinegar per quart may be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.

Recommendation: Use of a pressure canner will result in higher quality and more nutritious canned tomato products. If your pressure canner cannot be operated above 15 PSI, select a process time at a lower pressure.

If a procedure from the USDA Complete Guide to Home Canning for canning tomatoes offers both boiling water and pressure canning options, all steps in the preparation ("Procedure") are still required even if the pressure processing option is chosen. This includes acidification. The boiling water and pressure alternatives are equal processes with different time/temperature combinations calculated for these products."

You still must add the bottled lemon juice or citric acid when canning tomatoes. Perhaps you can freeze your tomatoes instead. Even commercial canned tomatoes use citric acid in them if you check the labels in the store.
Personally, I don't notice the added acid. Funny how we are all different in detecting it. I add a bit of sugar to my tomato dishes anyway, so maybe that is why I don't notice it.

The problem is that the processing time for the PC is predicated on the assumption that the tomatoes are acidified. The advantage of the PC is better quality (texture) and reduced time. If the tomatoes were not acidified the processing time would have to be increased, but as no recent testing has been done for that, we have no idea how much additional time would be required. (Not to mention the loss of improved quality from the shorter time.)

I suppose you could go without acidifying the tomatoes (I'm not recommending this, just saying what could be done.) if you were willing to boil the tomatoes for 10 minutes before use (plus 1 minute per 1000 feet). That would kill any possible active botulism toxin (but it wouldn't kill the spores).

I think we tend to underrate the potential of canned tomatoes to present serious health risks. We forget that while it's true most tomatoes are sufficiently acid not to need additional acidification, it doesn't take much to shift that balance. Not just the variety but condition of vines, reduction in exposure to daylight, degree of ripeness when picked, can all take tomatoes over the line into low-acid territory.

Carol

The University of Minnesota web site indicates two methods. The USDA and the Minnesota methods. USDA uses acid and Minnesota does not if certain conditions are met.

***It is important to be certain that the tomatoes used following these methods are underripe to ripe and not soft, overripe, decayed, one of the listed high pH varieties, or those of uncertain acid content***

In addition they recommend for either process ***For added safety, boil products 10-15 minutes before serving. The heat will destroy any botulism-causing toxins that may still exist despite the precautions taken.***

Zeuspaul

Here is a link that might be useful: Canning Tomatoes

zeuspaul ... looked up that site... very interesting. Particularly if you grow your own tomatoes and can avoid the known low acid varities. I wonder, though, how one can find out the pH of varieties that have come along since this data was reviewed and I presume updated in 2000. Wonder if there's a pH list by named variety?

Very difficilt to know what varieties are low acid, as it can also depend on the soil conditions, fertilizer used, as well as the type. Low acid breeds of tomatoes are not really going to be actually low in acid unless the soil they are grown in is also a high pH, and fertilizers used have very low acid content. A good example is the infamouse Vidalia onion. It grows only in a region of the country where sulfur levels in the soil are extremely low. If it were grown in a soil higher in natural sulfur it would be much less sweet. Tomatoes can vary in pH from 4 to almost 8, and potassium levels are also a factor in determining the taste.

As was mentioned, there is no guarantee that your tomatoes grown in your soil will have the same ph level as those grown by someone else.
When there are independent studies like that as in Minnesota, the USDA or Univerisity of Georgia/National Center For Home Food Preservation, the University of Georgia is considered the leading authority.
I asked this question a while back about the difference and was told this : "They ( University of Georgia) are the test site for all the USDA-tested recipes and therefore have the most reliable information."

Something as minor as picking tomatoes and then ripening on the back porch can result in increased pH. There just are too many variables to assume that a variety listed as "high-acid" will always be that way when harvested and processed.

Everyone on this Forum has a different threshhold for degree of risk. Only you can decide how you want to approach this issue.

Carol