Gross??? that's why we're here..to share gross. Tastefully, of course...never apologise.
So, the segment you mean was whole?? like the crescent shaped segments? Or do you mean the outer covering of the segments?
Chew your food well. VERY well. No matter what it is. Peas and celery both have lots of fibre. Different kinds, however.
Chewing is the start of the digestion process. Little pieces take up smaller space than larger ones do.
Oranges contain fibre. The covering of the segments will never be digested..it's part of the insoluble fibre that will help take up space as it's going through the digestive tract and help the stool from becoming compacted. Think vermiculite in potted plants. Insoluble, but absorbs water so that the soil doesn't become as hard as a rock when it dries out.
I don't think you need to worry about what food looks like when it goes through....make sure you're eating enough foods that will produce stool. That will get mixed in and you won't notice it as much.
Try not to get on the what you shouln't eat. If the mandarine oranges bother you by creating discomfort or diarrhea, then maybe eat a half or a few segments throughout the day or buy them in the little cups that don't have added sugar but just fruit juice. The segments are peeled.
I believe the more you are able to eat, the different fibres you ingest....the better your colon will function.
Try to find the balance so that you're feeling OK after you eat foods. If your bms are the same as always, but you just see segments..it's no big deal. With inflammation, the colon will work a bit faster and stool/debris will go faster through than it would if it wasn't inflamed.
My take on it..
Try not to obsess about every little thing that comes out. Carrots in the toilet were just that after chewing...not even phased by the digestive process. I stuck to cooked rather than raw..much better.
Just to add...you could consider to take digestive enzymes geared toward vegetable fibre. That might help how the things look in the toilet.