It’s winter so I find myself eating more soups and stews. They can be so good on a cold day.
But IMO celery tastes horrible and only subtracts from the flavor of soup by covering up other flavors. Why is it such a common ingredient? Do people actually like enjoy or is it serving some other purpose?
(Yes I avoid it in other foods too. Not to go off topic but water chestnuts are a fantastic substitute if you like the crunch. Try them instead of celery next time you make stuffing.)
Commercial pectin products often come from processed apple skins, and some other fruits but mostly from the skins anyway, so you’re spot on
No idea if peppers will replicate the stock texture of celery but I imagine it can’t matter too much. You probably have to be extremely sensitive and test a lot of samples to tell the difference for that kind of subtle texture
I personally like celery so I don’t share your problem but I rely more on boiled potatoes anyway in my soups/stews for the starch as a mild thickener. I also love potatoes (:
Edit: here’s a source I used https://pickyourown.org/pectin_levels_in_fruit.php