The USDA in the past has sometimes seemed very subtle in what it “approved” and “didn’t approve” of.
Granted, all the recipes in its “Complete Guide” are of course things it “approves of.”
But they don’t even use those words, “approve” and “disapprove.”
In USDA canning lingo, “has not been recommended” equals “recommended against.”
Lately, through the National Center for Home Food Preservation (NCHFP), explicit advice is starting to come through more clearly.
This page will try to track some of that advice.
Explicit Recommendations For
1. Keep beets hot while canning
The USDA Complete Guide (2015, page 4-9) has you parboil beets, then “Cool, remove skins, and trim off stems and roots.” Debate went on in the blogosphere about that instruction, with some people interpreting it to mean that you should let the beets get quite cold.
The NCHFP weighed in in 2015 in a post on their blog to settle the matter:
Beets should be hot when packed into jars for pressure canning, not cool and not cold. After parboiling them to get the skins off, let them cool only enough so that you can bear to touch them to peel them. But do not chill the beets otherwise; the canning recommendation presumes reasonably warm beets going into the jar.”  Christian, Kasey. Plain or pickled, they make great treats. What are they? Yes, they’re Beets! Preserving Food at Home blog. 18 February 2015. Accessed March 2015 at https://preservingfoodathome.com/2015/02/18/plain-or-pickled-they-make-great-treats-what-are-they-yes-theyre-beets/
The instruction was also clarified within 2 months on the NCHFP’s version of the USDA’s directions:
Cool just enough to handle without burning yourself, then remove skins, and trim off stems and roots.”  https://nchfp.uga.edu/how/can_04/beets.html
Explicit Recommendations Against
1. No pressure canning in electric countertop pressure cookers
The NCHFP has explicitly recommended against using an electric pressure cooker for canning, even if the manufacturer says you can.  Christian, Kasey. Can I Can in a Multi-Cooker? Preserving Food at Home blog. 25 November 2014. Accessed March 2015 at https://preservingfoodathome.com/2014/11/25/can-i-can-in-a-multi-cooker/
2. No using pressure cookers as pressure canners
“In the late 1980s the USDA published its recommendation to not use pressure saucepans (small cookers) for home canning.” National Center for Home Food Preservation. Burning Issue: Canning in Pressure Cookers. 7 November 2006. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/pressurecookers.html
3. No adding just any vegetable to the USDA “choice” soup recipe
The NCHFP offers a “choice” soup recipe, where you have a lot of leeway on the ingredients you can choose to use with the main proviso that half the volume of the jar be liquid. They have since explicitly come out to emphasize the line in the direction that says that you can only, however, choose ingredients that “already have separate canning recommendations.”
The procedure for canning soup says ‘Each vegetable should be selected, washed, prepared and cooked as you would for canning a ‘hot pack’ according to USDA directions’, which means that there must be a canning recommendation for each added ingredient. As examples, for this reason we cannot recommend adding cabbage nor cured meats like cured ham to canned soup.”  Christian, Kasey. Simply Soup. Preserving Food at Home blog. 5 March 2015. Accessed March 2015 at https://preservingfoodathome.com/2015/03/05/simply-soup/
So this means no cabbage, no celery, no cauliflower, no zucchini, etc used in that recipe as an ingredient.
Onion can be used, because it has a tested canning procedure in So Easy to Preserve (2014, page 92.)
And to be clear, celery can be used in tested fixed soup recipes from reputable sources that call from it, such as Ball’s Vegetable Soup because they have specifically tested for it. The above just applies to the USDA free-wheelin’ soup recipe.
See here for full details about the soup.
4. No home canning of cured meats
For a full discussion, see: Home canning cured meats.
5. No home canning of dairy products
This includes adding any dairy as an ingredient to something you are canning. See: Canning Controversies: No to Home Canning Dairy Products.
References [ + ]
|1.||↑||Christian, Kasey. Plain or pickled, they make great treats. What are they? Yes, they’re Beets! Preserving Food at Home blog. 18 February 2015. Accessed March 2015 at https://preservingfoodathome.com/2015/02/18/plain-or-pickled-they-make-great-treats-what-are-they-yes-theyre-beets/|
|3.||↑||Christian, Kasey. Can I Can in a Multi-Cooker? Preserving Food at Home blog. 25 November 2014. Accessed March 2015 at https://preservingfoodathome.com/2014/11/25/can-i-can-in-a-multi-cooker/|
|4.||↑||National Center for Home Food Preservation. Burning Issue: Canning in Pressure Cookers. 7 November 2006. Accessed March 2015 at https://nchfp.uga.edu/publications/nchfp/factsheets/pressurecookers.html|
|5.||↑||Christian, Kasey. Simply Soup. Preserving Food at Home blog. 5 March 2015. Accessed March 2015 at https://preservingfoodathome.com/2015/03/05/simply-soup/|