why can't oven canning ever be safe?
First, I am aware that BWB and pressure canning are the only recommended methods of preserving food today. This isn't going to be a boiling green beans thread.
What I am wondering is why oven canning high acid foods is condemned as always unsafe. I understand that air is not as efficient a conductor of heat as water, so 200 degree air won't transfer heat into the food as well as 200 degree water. But why wouldn't sterilized jars, set into a water bath (say 3/4 up the jar) in a 275 oven for 4 hours, for high acid/high sugar foods only, reach a safe temperature? Is the main concern here jar breakage?