I have been to several QPO concerts already and people were quiet enough. Eating during some events is normal in several countries, I was in germany before, they even have "lunch seminars" where you give your talks in front of people eating...

But noisy eating, during a religious event... If anyone is aware of a culture/religion that allows that kind of stuff please say so.

And, again, this not about locals or turkish people, this is more of a general crowd behaviour.