Hello. As long as your pressure canner is in proper working condition --- gasket in good condition, if dial gauge - checked for accuracy (annually before start canning); if weighed gauge - vent pipe clean, using an approved process with correct amount of water (typically 2 to 3 inches) unless the process calls for more, you should be good. While processing make sure no steam leaks or excessive dripping as that would be an indicator that the canner isn't properly closed and could lead to water loss. Hope this helps and thank you for using Ask Extension.

I processed eight pints of collards greens. I had brought the canner up to pressure but ran out of time so I turned it off, did my errands (gone for about four hours). Then restarted processing. let the canner cool on its own. Removed the lid, left the jars in the canner for maybe an hour. Then removed and continued cooling at room temperature. There were bubbles in the jars. Also the water in the canner was discolored so I figure siphoning happened. Then I opened one jar and tasted. The food had a nasty flavor. Is this flat sour? How long does flat sour take to develop?

On a different note, all but one of the materials I've read say you need LOTS of collards to start. I harvester 14lbs plus 2lbs of turnip greens from the store for the recipe I followed. I had to wilt just to manage the quantity. The eight jars I filled used only about 1/4 of the wilted greens. What the heck! Now I have to do something with the rest of my beautiful garden fresh collards, now wilted and taking up huge space in the frig. Suggestions?

Patricia, So sorry you had issues. Well, first, your greens were over-processed. It takes time to bring up to pressure and then to stop for four hours, the greens are still cooking. Then when you returned, you processed which would have been another 70 minutes for pints and that, just the process time, not including bringing up to pressure and the dropping back to zero. So definitely over-cooked. Since water discolored, probably did have some siphoning and that could have been due to stopping and then restarting.

As to flat sour, it occurs when jars are left in the canner too long or product not cooled properly which definitely could have occurred with what you did. There are different types of bacterial, and there are some that can survive the canning process and can lead to flat sour. Based on what you did, this probably occurred. You must follow approved, science based processes. Extension always recommend tested recipes and a good source is the National Center for Home Food Preservation. If you do not find a recipe on that site for the product you are interested in, it probably means it doesn't exist. YouTube and Pinterest are not recommended sites.

As to the amounts of product needed, NCHFP recommends about what you had. So not sure of the discrepancy except maybe the recipe you were using if it wasn't NCHFP. If it was, I have no idea. Next recommendation would be to freeze the rest. Hope this helps and thanks for using Ask Extension.

Thank you so much for confirming my after the fact analysis. I made another. Batch today, but haven't tasted it yet. Had some siphoning again, though much less. And yes, I'm going to cook the remainder using my favorite recipe and freeze.