Hi, Thanks for using HCM.
Usually if you have taken whole part of plastic, it will be excreted in feces and need not to be any problem. But rarely it can cause obstruction if not moved in alimentary canal or it can cause ulcer if any sharp edges.
Since it has dissolved in food, If not excreted and constant irritation persist in lumen then there may other problem like intestinal spasm
, loose stool
etc. Don't worry now as normal tendency is to remove unwanted substances and get examined if any problem/symptom arises. Then you may require endoscopy
Hope I answered your question. Consult your doctor for further examination and management.
Feel free to ask me if you have any further queries.
Wish you good health. Take care.