I recently made a batch of snack sticks which required fermentation. Each day I would cut about three inches off a snack stick and remove the mince to test. Being impatient, I did this frequently.
At first, I could simply squeeze the mince out of the casings however the longer they rested and fermented the tougher this became and after a day I had to slice the stick and scrape the mince out of the casing. On the second day I was unable to get all the mince out of the casing since about 2 mm had adhered like glue to the casing.
I don't know if this would explain why people have trouble with collagen casings but it did appear to me that if you have proper myosin extraction the mince will adhere to a collagen casing very well if given the time. So I wonder if the problem might be explained by impatience and poor myosin extraction.
Here is a photo and if you look at the top line where the casing is cut you can see an area which has essentially bonded to the casing and would require a knife to remove.
![Image](https://i.imgur.com/ZhUcevjl.jpg)