Each museum has its own rules.
Here is what the Louvres regulations say:
It is forbidden to enter with excessive quantities of drink or food at the discretion of the agents carrying out the entry control in the reception areas.
It is forbidden to drink and eat in the spaces where works are presented. For this purpose, food and drinks must be kept stored in a closed bag. Only the consumption of plain water, away from the works is tolerated.
Controls may now be tighter.
Here is what happened two weeks ago at the Louvre in front of the Mona Lisa painting:
“A visitor simulated a disability situation to use a wheelchair and approach the work installed in a secure display case. The Louvre has applied its usual procedures for people with reduced mobility, allowing them to admire this major work of the Louvre. »
“Sitting near the work, this individual threw a pastry that he had hidden in his personal effects onto the window of the Mona Lisa. This roll had no effect on the painting, which suffered no damage. »