More on canning butternut squash: choosing from two different recommendations

Yesterday I made myself super happy by putting up 7 quarts of butternut squash. I followed the USDA's method, while cross-referencing with the instructions given in the Bernardin Complete Book of Home Preserving. And I noticed a minor difference between the two, a difference that is hopefully not as wildly shocking and controversial as the sudden, inexplicable, unbelievable announcement from Ball that you don't actually need to heat up your canning lids before applying them to your jars.

To can winter squash, you peel the vegetable, scoop out the seeds, and chop the flesh into 1-inch chunks. You drop the chunks into a stockpot, cover them with water, bring the pot to a boil, and gently cook the chunks for a couple of minutes. Then you use a slotted spoon to fill your jars and finally top off the jars with liquid, leaving 1 inch headspace.

But what liquid?! There's where USDA and Bernardin differ. USDA (2009) says to simply use the liquid that the squash cooked in. But Bernardin (2012) says to use fresh boiling water! What to do?

If you use the cooking liquid, then you'll be retaining more nutrients, particularly beta-carotene, in your jar. Now, it's not that the pre-pack cooking leaches all the beta-carotene out of the squash, since it does keep its bright orange color and the liquid is only very pale orange. But why not seek to maximize your nutrition here?

Is it a matter of hard water? If the cooking liquid started as hard water, will that give an off-taste after canning and long-term storage, which you would avoid by using fresh hard water instead? That doesn't seem to make sense. Am I missing something else instead? I don't think I am, and I don't think the issue is hard water.

So maybe it's a matter of lowering the density of the liquid in the jar, thereby reducing the risk that heat may not penetrate to the center of the product. The question could be whether the particles of squash suspended in the cooking liquid dangerously increase the packing liquid's density. But if that is the rationale, I don't agree that there's truly a risk here. The squash cubes themselves will be more dense than any liquid surrounding them. Although the jars do end up with with some shredded bits of squash in them, it's nowhere near the amount and density of particles that you'd have in jars packed with purée, which you cannot home-can because of the heat penetration problem.

In the end, I'll have to respectfully disagree with the Bernardin instructions there. I suspect that their concern is the density of the packing liquid. But I can reduce that risk by being careful not to overcook the chunks of squash before I pack them (so that they don't deteriorate into purée in the jar). And I like to try to keep as much nutrition in the jars as possible. Throwing out the cooking liquid -- that is, unless I use it as a soup base outside of the canning project -- would really be a waste.

Are the shredded squash particles in the jar on the left what Bernardin is concerned about? I think that it makes for an unattractive jar, but that there isn't enough of it to dangerously increase the density of the packing liquid here.

And P.S.: Thanks, Mom, for the birthday present of the Bernardin book!