Why do people insist on using outdated recipes for canning?

It's amazing to me that when people talk about canning foods often times you will hear "We've always done it that way" or "That's the recipe my grandmother used."  or  "Nobody has died yet."  All of those statements may be true but why do recipes change over time as more research is done?

Well, there are several factors that could be involved.  For instance, "We've always done it that way" or "That's the recipe my grandmother used" could have worked because back when our grandmothers were a lot younger the vinegar that was sold was often stronger than the 5% acidity that is commonly bought today.  And think about heirloom vegetables.  So many people planting gardens want heirloom vegetables because the ones you get now have been modified.  Did you get that? The ones now have been modified.  That means something about the make up of those vegetables is different than the ones we used to get.
So it boils down to this, as the things we use in our recipes change so should the recipes.

It's just that simple. If you want to can everything from apples to zucchini nobody will know if you used your grandmother's recipe or a currently approved one.  What they are going to care about is how good it tastes. And if you really, really, really love your grandmother's recipe contact your county extension office and have them check it over.  It might still be okay. But if there are any subtle changes that need to be made to make it a safe recipe they can help you make the change.

Keep your recipes safe.  It would be a super bummer for someone who used to say "Nobody has died yet" to have to stop saying that.  It's not worth the risk.