This is a question I went down a rabbit hole on too, so here is what finally made it click for me.
Most of the confusion comes from lumping two very different compounds together:
1) The cyanogenic glycosides (the "toxin") are concentrated in the seeds, stems and leaves, not really in the juice itself. They start breaking down with fairly gentle heat, and straining the seeds and stems out does most of the work before heat even matters. So a strained syrup, or a tincture made from strained juice with no crushed seeds, is already in low-risk territory.
2) The anthocyanins and other antiviral compounds (the stuff you actually want) are the heat-sensitive part. These are what degrade with prolonged, high heat: a hard rolling boil, or pressure-canning for 45 minutes, will cost you a real chunk of potency. But they hold up fine to a gentle simmer.
So the sweet spot most people land on is a low simmer kept below a boil (around 180F / 85C is plenty) for 30-45 minutes with the lid on. That is hot enough to settle the toxicity question and gentle enough to keep most of the good stuff intact. Steam-juicing and water-bath canning both push past that, so they trade some potency for convenience and shelf life. Not wrong, just a trade-off worth knowing about.
Two things that matter more than people expect:
- Add the honey after the juice has cooled below about 110F, not while it is hot. Otherwise you cook the honey's own enzymes and benefits right out of it.
- If you want maximum potency for storage, freeze the finished concentrate in small portions and thaw as needed, rather than canning. You lose almost nothing that way.
And on the tincture question specifically: an alcohol tincture from strained juice (seeds left out) actually preserves those heat-sensitive compounds better than any cooked prep, which is why a lot of herbalists consider it the strongest remedy of the bunch. Grinding the seeds into it is really the only part I would steer clear of.
