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Sep 5, 2009 11:28 PM

Jam Making: A Food Safety Q


My mother in law was just over from Germany. She is a great jam maker and has an envious pantry of things she has grown and preserved herself. So, I had her teach me how to make jam while she was here. She washed the jars very, very well, but there was no sterilizing of the jars in boiling water. I had always thought that was a necessary step. Please advise.

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  1. As long as the processing time is 10 minutes or more (typical for 1/2 pint jars and larger) you do not need to sterilize the jars before hand, as they will be sterilized in the canning process. If you process for less time, you do need to sterilize.

    7 Replies
    1. re: dct

      What do you think of sterilizing by washing and then putting the jars/lids in a 200 degree oven for half an hour? I read about this method in one place, and have been using it as it's simpler for me in a small kitchen than to boil them etc. But, I finally got the Ball book, and it doesn't not appear to approve of this method. Thanks.

      1. re: MMRuth

        I use this method. It'll kill most of the bacteria and mould spores and yeast. Water just conducts the heat faster than air.

        1. re: MMRuth

          My mother taught me to do this.. it's much less dangerous to your health than messing around with pots of boiling water!

          1. re: Kajikit

            And it takes up less counter space.

          2. re: MMRuth

            I have to admit that I've never processed anything less than 10 minutes, so I've never really looked at sterilizing, except for the occasional single jar for preserved lemons or something. My question about all methods of sterilization is how can the object remain sterile once you remove it from the water, oven, or dishwasher?

            1. re: dct

              Yes, I've wondered about that too. I take the jars etc. out of the oven one by one as I fill them.

              1. re: MMRuth

                I put mine in a 200F oven. And take them out one by one as I fill them. It's going to remain sterile because the jar is 200F and doesn't cool down to a liveable temperature right away. Even if some nasty gets on it, it won't live.

        2. I always just run the jars through the dishwasher on the hot cycle as I'm prepping the fruit. I've never boiled the jars -- too hot! :)

          1. My husband's grandmother doesn't boil the tomato jars or process them in water- she just puts boiling tomatoes in very clean jars with boiled lids and goes with it. So far, so good- but I'm still boiling mine.

            1. What do you mean about 'processing time'? Is that how long it takes to pour hot jam into the jars and to seal them up?

              5 Replies
              1. re: relizabeth

                That is the amount of time the jars are in the hot water.

                1. re: relizabeth

                  There's a difference between UK and Cdn instructions for jam and US instructions. In the US (at least on the pectin brands I was looking at online), the instructions are to process the jars in a water bath after filling. The recipes in the Certo package (most common pectin here in Cda) say hot jars, hot jam, hot lids, fill and seal. No water bath.

                  1. re: relizabeth

                    I've been making jam for thirty years and never got a "bad batch." (everyone's still alive and kicking, too. ;-) Long ago I decided that the most reliable method of sterilizing the jars--given cat hair in the air, hands that might not be entirely clean, fruit that was a bit dirty or something, etc., etc, --was to just go ahead and process them all. For half pints, I do 10 minutes; 15 for pints. It's not particularly dangerous as long as you have the right tools: I have a special metal rack that goes in my canning kettle, that holds 7 jars, and the handles convert to bails that hold the jars ABOVE the water, by clinging to the sides of the kettle--thus you aren't reaching directly into the hot water to retrieve the jars. IN addition, I use a pair of special canning tongs, that grip the jars' necks tightly, so that I don't risk spacing out and dipping my fingers in the water while pulling out each individual jar.

                    Just wait for the canning water to cool completely before carrying the kettle to the sink to pour it off, and you should be fine and dandy!

                    1. re: Beckyleach

                      The OP's follow up question about processing time leads me to believe she was taught the open kettle canning method. This was used for high acid foods such as pickles & high sugar foods like jams & jellies. This is when the jars are filled & sealed & not processed in a hot water bath or pressure canner.

                      This is no longer considered a safe method. In the past, homes were not as warm, canned goods were usually kept in cellars & they were eaten by spring. They were basically refrigerated. (If you don't want to process, you can still make freezer jam & refrigerator pickles.)

                      Also to Coconuts, todays tomatoes are not as acidic & it is recommended that they be pressure canned, rather than hot water bath. They definitely should not be canned using the open kettle method, no matter how well you sterilize your jars.

                      As long as you use the appropriate processing method for what you're canning, you don't need to sterilize your jars. They DO need to be hot however to avoid breaking when adding the hot contents. Using the oven, boiling water or dishwasher all work.


                      1. re: tullius

                        "As long as you use the appropriate processing method for what you're canning, you don't need to sterilize your jars."

                        This is true if the jars are going to be BWB'd or pressure canned 10 minutes or longer. Anything with a shorter processing time, the jars should still be sterilized. Simply drop them into your boiling water bath or steaming pressure canner to sterilize while you're cooking up your recipe. By the time your recipe is ready your jars should be too. No point wasting more energy on ovens and dishwashers for your jars when you've already got water boiling in your canner.

                        Straight tomato recipes like whole, diced, or crushed tomatoes can be waterbath processed with the addition of 2 tablespoons of commercial bottled lemon juice (for acidic consistency) to quarts and 1 tablespoon per pint. Add the lemon juice to your jars before packing the tomatoes and adding boiling liquid. Sauces that have added low acid ingredients (like spaghetti sauce) should be pressure canned because, in addition to the acid content of tomatoes varying, every time you add a low acid food (like bell peppers, onions, or garlic) to the tomatoes you bring the acid level that much lower with each addition. A good rule of thumb is to process a sauce for the same amount of time as the longest pressure canning time for the individual ingredients.