When I am oven canning dry beans I get moisture in the top of the jars. I've put them back in the oven for more time up to 10 hours and I still get a small bit of moisture in the top of the jars once they seal.
Oven Canning Dry Beans:
The oven canning method has been in place for quite some time now. This method is for canning dried beans, flour, oats and nuts.
What they don't tell you is this: Oven canning will actually decrease the shelf life of food by 50%. Did you happen to realize that the key enemies of long-term food preservation are heat, air, light, and bugs. The safest way to can and store any dry foods such as oats, flour, and beans is by using mylar bags, food-saver bags or even food grade buckets. You will store these items in one of the above safe storage bags or bucks and use food-grade diatomaceous earth and sprinkle some in the storage bag.
The reason you have moisture in the top of your canning jars is because you used water around the lip of the car so the lids would seal. The moisture has entered into the jar and now it is trapped in there. No matter how long you keep these in the oven the moisture will not leave. Furthermore, the longer you keep heating up the beans in the jar, the less nutrients are left in the beans.
Personally, I would recommend not using this method to try and store your dry foods. It isn't safe and heating up the foods in the jar is destroying the nutrients in the foods.
Please try a safer method of preserving your food. Use one of the safe food storage bags and seal your food in them. It is much healthier for you and your family.
This is not a safe method of canning. Dry heat is not the same as moist heat. The jars are not being heated evenly and that is why you are getting moisture.
The problem is moisture in your beans. If you have moisture in your jars put back in the oven, but wait 7 hours. Keep humidity down in the house. Do not use dishwasher, washer or dryer, It causes humidity. So make sure your house is free of humidity.
Then, vacuum seal them.
I have dry canned my beans, rice and noodles this was for years. I used to have problems with moisture. What I do is bake at 200 degrees for 1 hour, then I turn off the oven (and light) and leave the jars in there until they are completely cool.