Monday, September 5, 2011

Defeating the Killer Tomato

     No, this isn't a review of the campy horror films so if that's what you're looking for, sorry to disappoint. This is a post about canning tomatoes, or in my case, trying to can tomatoes.

No this hilarious picture is not mine, credit belongs elsewhere
I'm just not sure where

     Why the title? Tomatoes and their salsas, sauces and relishes are probably the most common of home canned products. Many people take a real risk because they are thought of as high acid. They may taste acidic but they straddle the line of the 4.6 pH level needed to process things safely in a boiling water bath canner.

     What does that mean? Improperly canned, there is a risk of botulism. Now the odds of contracting botulism are low, but they are also potentially lethal. Not really something I am prepared to risk.

     I have things I can that have vinegar in sufficient amounts to lower the pH into the safe zone, ketchup and chili sauce. I've never, and still don't, have any concerns about their safety. I do however make tomato butter, the recipe source was reliable, and it is combined with a truly high acid source, apples. I've made it and enjoyed it for years, but after some reading...............

     Here is where things start to go down hill, at least for me. I need to understand the why behind what I'm doing for it to stick. Because of that, I tend to do an annoying amount of research and questioning before I start something, forewarned is forearmed. As I was researching canning with a pressure canner, I came across things which have made me question what I thought I knew.

     The first thing I did was read the instructions that came with my new pressure canner. Check, I understand how it works. I searched the internet on pressure canners and canning. Check again, sources agree, no problem. Now it is time to get the recipes. WTF happened here. No check, wildly different ingredients, preparations, procedures, cooking times etc. Back to the drawing board.

     I decided I needed to understand just what the conditions were that provided the growth of the botulism toxins, among other things, that can spoil all of your hard work. Along with that came ways to destroy, delay or reduce the above. If I understood this, I could make informed decisions about the recipes I had seen or perhaps adapt the ones that were a little on the shaky side of safe.

     That went well. There is a lot of solid science out there about food borne pathogens. There is also a lot about what affects their growth or kills them. It is pretty straight forward. Lots of information on how what you are canning can affect them, product density, combinations of ingredients, all the good stuff. Finally, an incredible amount published on the difference between doing it at home and how it is done commercially, irradiation, anti-microbials, higher pressure and heat that home canners can't duplicate. I've got this now.

     Back to the recipes. The first thing to do is make sure your source is a good one. Next, make sure it is current. Food safety recommendations change all the time so you have to keep up. Check and check again.
I use the National Centre for Home Food Preservation and the Canadian Food Inspection Agency. They are the two of the best sources for current information and I have yet to find an instance where they don't agree.

     I decided to use recipes from only one trusted source. I read all of the recommended supplements then started comparing recipes to the information I had. The only place they don't agree is in the processing of tomatoes. What is up with that?

     Most of the recipes require tomatoes to be acidified for pressure or boiling water canning. Preparations are the same, obviously processing times are different but why acidify for pressure canning. I thought the high heat was sufficient. Where is my understanding going wrong? Pressure canning meat or low acid vegetables requires no acidification, why are tomatoes the exception?

     I did say most, there was a recipe for paste that added low acid peppers, cooked for ever then processed in a water bath canner for a long time. No acidification, no pressure canning instructions? This one caught my eye because it is almost exactly like my tomato butter recipe, same cooking and processing time and roughly the same proportions of ingredients. Why is this one safe?

     A sauce recipe that didn't require acidification didn't have water bath instuctions only pressure canning. This actually does make sense to me as it is how I understand the process to work. But if that is the case, why acidify the other preparations for pressure canning?

     I understand this is over simplifying things, you can't really compare. There are so many factors that affect the outcome, it would be impossible to cover every scenario. Is the acidification an added precaution? I can live with that explanation, it makes sense, but it bothers me that I don't know.

      Why wouldn't that be in the instructions? That's easy, people would skip that step. We are notoriously bad at following instructions, even ones designed for our safety.

     At the end of the day, I have to take it on faith that these agencies know their stuff. I do use the guidelines even if I can't make sense out of them 100% of the time. If they seem overly cautious is that a bad thing? Not for me. (but seriously, if you do actually know the answer let me know, it drives me crazy not knowing, LOL.)

    Take care and can safely, keep those killer tomatoes at bay.

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