Recently, I've started seeing people wanting to pressure can items that really shouldn't be pressure canned. Everything from tomatoes to jams to pickles!
Let's start over with the basics.
Waterbath canning processes are used for high acid content foods. Tomato products like basic sauce, diced, salsas are high acid. Jams, Jellies and Fruit Butters are high acid. Pickles are of course high acid from all the vinegar. Waterbathing gets your jars and product to 212 degrees Fahrenheit (sea level boiling point). This is enough to kill most germs and quite a few vitamins. The only thing germ-wise still remaining MIGHT be Clostridium Botulinum. (The germ that causes botulism illness.) The Big B won't survive in a high-acid environment. Waterbathing is considered safe for all these type items.
Pressure canning builds steam inside the canner that elevates the temperature of the jars and product to 240 degrees Fahrenheit (sea level). That is enough oomph to kill off the Big B. Pressure canning is used for low acid foods that cannot keep the Big B from growing because their low acid content is friendly to it. Now your food is truly sterilized. Ever heard of an autoclave? That is how the hospitals sterilize surgery equipment to use on humans. You've basically just done this to your food and jars using your pressure canner. There are some vitamins that will survive this, but not many.
NOW, you get into the discussions about all the different types of canning. Folks across the pond don't readily have access to pressure canners like the US does. Many of the Amish and Mennonite communities waterbath everything as well. There are many folks that cannot currently afford the cost of a pressure canner and waterbath works for them. Then you have the folks that are brave enough to open kettle can, steam can, or even oven can.
I personally will waterbath low acid foods that already have a bbq style sauce on them like BBQ Pork, Taco Meat, Sloppy Joes; I have found in the pressure canner that the sauces scorch and the end product isn't very tasty. Otherwise, I choose to pressure can all low acid foods. You won't find me trying to pressure can items that don't need it.
I don't know if folks have gotten it into their heads that pressure canning is "better" for you since it "kills everything" or what. Or maybe folks think they have spent this money for this canner that it needs to be used for absolutely everything. Or they only wanted to buy one type of canner, maybe? Pressure canning processes are not the be all, end all.
You can waterbath can in most any tall stock pot. You can use a kitchen towel for a bottom rack in a pinch. I've used old canning jar rings for a rack before. You don't have to purchase a specific "canner" to use this process. Old granite ware canners can be found for cheap on marketplace too. You just have to have enough height in the "canner" for water to get to a rolling boil and stay that way an inch over the top of your tallest jar. I routinely waterbath can small jars (pints and half pints) in my pressure canners. (The p.c. aren't tall enough to w.b. quarts.) They heat up quick and I can run batches through fast.
Timing is the kicker in any canning process; pressure or waterbath. The reason folks get so worked up about how long to process items is because the heat around the jars has to be high enough and kept there long enough to penetrate to the center of the product inside the jar. Even if the product is broth, it is still a bit thicker than plain water and you need to maintain that 240 degrees inside the pressure canner to get to the center of the fancy water inside the jar.
When waterbathing, you don't start timing until the water gets to a rolling boil; that hard angry boil that will spill over the top of the pot if you're not careful. When pressure canning, you don't start timing until the gauge shows the 10 lbs (sea level) or the weight starts dancing. The start of the time means that your canner, water and jars are hot, but the length of time is what gets the heat to the center of the product. That is why beans and meats are 90 minutes inside the pressure canner; those are pretty dense. It makes no difference if your item is raw packed, hot packed or started off cold. You don't start timing until you get to these certain points and you time accurately to make sure you've killed the germs.
There is a big myth that the "new" tomato varieties have the acidity bred out of them. The flavors have changed but the acidity is still there. I've read in a couple newer books that "they" are recommending pressure canning tomatoes and that just blows my mind. Along with a healthy dose of frustration. Why do "they" think we need to kill everything inside our food, including the good stuff? There has been just as much breeding done to apple varieties and "they" haven't started recommending that you pressure can those yet, have they? Correct me if I'm wrong.
Fructose is a type of sugar found naturally in our fruits and veggies. Fructose starts to caramelize at 230 degrees Fahrenheit. (Thank you, Science of Cooking!) That is 10 degrees BELOW the temperature you're reaching inside the pressure canner. Why do you want to burn your food?
I know fear mongering is a big part of it and I see scores of people online that are so scared of processing their own food that they clasp to the "rules" like a religion. AND like religion, they want to press those rules right over onto everyone else. If you understand what is happening to your food inside the jars and then inside the canners, you will become more comfortable with the entire process and be able to see around all the "recommendations".
The whole point of home canning your food is to have healthy, wholesome food on the shelf that you know what is in it. It can save alot of money as well because you can buy bulk items and break them down into usable sizes.
Home canning also provides a non-electrical source of long term food preservation. Foods like meats and potatoes wouldn't stay good for very long without electricity; UNLESS it's safely packed inside a jar and sealed. You have years before the food could go bad. I've seen 40 year old jars of green beans that looked as fresh as the day they were packed. That is a big longer than my personal threshold of edibility, but I am still using tomatoes from 2012 and green beans from 2017 that I personally did not can. (I purchased a pantry from a grandpa that was moving to the nursing home.)
Give some thought to how much good stuff in your food that you want to kill along with the germs before you pull out the pressure canner to seal pickles....