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How to Can Tomatoes Safely

Safe canning recipes include lemon juice. 

with Sharon Peterson

If you are learning how to can tomatoes, I highly suggest checking out some of the latest methods suggested. 

Canning tomatoes has been traditionally considered safe using the water bath canning method. However, acidity levels have changed and are now very close to the safety borderline of acidity. The standard recommendation is to add acidity to tomatoes to make them safe.  

There is much debate about this recommendation.  Just remember there are no canning police.   There is no one to come and ensure you are using the latest methods.  YOU are responsible for YOUR health and the health of your family. 

How to Can Tomatoes: There’s a lot of misinformation with regard to safe and best practices out there. Learn how to properly can tomatoes so they are safe and don’t cause illness at

How to can tomatoes with lemon juice. 

It's actually very simple.  Give tomato products a dose of bottled lemon juice. 1T per pint/ 2T per quart. This will raise the acid level and make it safe for a boiling water bath.  No questions, no doubts.  

Confusing information?  Yes. 

Please note-  ALL official recommendations I've read suggest using acidification juice when you are waterbath canning tomatoes. So, if using a waterbath, I also suggest that you use lemon juice. 

I have seen differing recommendations from different extension websites regarding canning tomatoes in a pressure canner.  Some extension websites recommend lemon juice even when pressure canning.... some don't.

I called my extension here in Colorado to verify what I read.  (see quote below) The person I talked with confirmed that lemon juice is often recommended for all canning by some extensions.  However the Colorado State website states that if you are using a pressure canner acidification is not needed.

I included quotes from both sources a bit down on this page plus links to the websites so you can check it out. 

How I used to can tomatoes... and what I now do.  

I used to leave out lemon juice when I used a pressure canner.   However, lemon juice or other acidification certainly won't hurt anything, plus it adds an extra level of protection.  I've never tasted a difference.  Thus I've decided to go ahead and add the acidification whenever I am canning tomatoes... waterbath OR pressure canner.  This is what is recommended by most extensions.  You have to decide for yourself. 

Please if you don't agree or understand this recommendation contact your extension office. They should be willing to discuss it with you. I can only report what is recommended.

You need to make you own decision as to whether you want to include the lemon juice in your pressure canner or not.

Remember - If you add vegetables you must always use a pressure canner.  Adding acid to these types of recipes won't change the fact that the added veggies must be pressure canned.  Examples would be stewed tomatoes or tomato based vegetable soup, spaghetti sauce.

How to can tomatoes - Quoted from the NCHFP website

 Caution: Do not can tomatoes from dead or frost-killed vines. Green tomatoes are more acidic than ripened fruit and can be canned safely with any of the following recommendations.

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.

How to can tomatoes  - Quoted from the Colorado State Extension Service.

Although tomatoes are considered a high-acid food (pH below 4.6), certain conditions and varieties can produce tomatoes and tomato products with pH values above 4.6. When this happens, the product must be canned in a pressure canner as a low-acid product or acidified to a pH of 4.6 or lower with lemon juice or citric acid.

Research has found several conditions that can reduce the acidity of tomatoes. These include decay or damage caused by bruises, cracks, blossom end rot or insects, and overripening. Tomatoes grown in the shade, ripened in shorter hours of daylight, or ripened off the vine tend to be lower in acidity than those ripened in direct sunlight on the vine. Also, tomatoes attached to dead vines at harvest are considerably less acidic than tomatoes harvested from healthy vines. Decayed and damaged tomatoes and those harvested from frost-killed or dead vines should not be home canned.

To ensure safe acidity in whole, crushed or juiced tomatoes, add lemon juice or citric acid when processing in a boiling water bath. Add 2 tablespoons of bottled lemon juice or 1/2 teaspoon of citric acid per quart of tomatoes. For pints, use 1 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 the taste, if desired. Four tablespoons of a 5 percent acidity vinegar per quart can be used instead of lemon juice or citric acid. However, vinegar may cause undesirable flavor changes.

From my inbox:
How to Can tomatoes. Pressure Canning tomatoes... the old way?

Here is a question I received in my inbox.  It is in regards to pressure canning tomatoes with methods taught by relatives who have been doing things the "old" way for many years.  This is always a hard situation.  You don't want to offend your well meaning friend or relative... but, I don't suggest you just go along with them either.  

Dear Sharon.

I love your site! My mother-in-law, who is 85 has been canning all her life. --- This is the first year ever they have not had a garden. I have been buying fresh produce and taking it to her this summer.

She has taught me how to can tomatoes and green beans in a pressure canner. I have a couple of questions for you.

She has been canning tomatoes in pints for ever, processing at 5lbs for 10 mins, their elevation is about 1400 ft above sea level -

Our home is about 1200 ft above sea level, I have done 21 pts everything is sealed and everything is beautiful. - the question is: are they safe? should i reprocess them? most were done this weekend. Maybe I am just reading too many opinions, we have been eating them this way for years.

Thanks so much for your time - GREAT SITE!!!!

~ Bobby, VA

Bobby,   Thanks so much for you positive comments on my site. You made my day! 

As far as your MIL canning procedures. Five pounds is not enough pressure, and 10 minutes is not long enough.  New testing has changed what is recommended.  Tomatoes need to be pressure canned for longer than your MIL suggests.  Here are full directions.  Canning Tomatoes 

You said you have been eating them that way for years with no problems... so I can understand wondering what all the fuss is about.    This is one of those personal decisions. I can only suggest sticking with the current recommendations. You may have seen this already but, I wrote about unsafe or outdated canning methodsYou could also check with your local extension service

Again I want to thank you for your excitement over my site. I have enjoyed building it and am glad some are finding it useful.  You are a sweetie for bringing your MIL fresh produce. I'll bet she misses having a garden and appreciates your thoughtfulness too.


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