I read a book about food cultures of three immigrant groups who all immigrated around the same time: Jews, Italians, and Irish. The biggest change was in America meat was much cheaper and more available, while all three groups had meat rarely or for special occasions back home, so what we think of as traditional food for the three groups is not actually what they ate on a day to day basis before they immigrated.

The very interesting thing about the Irish though was for the other two groups there was an elite they had looked up to, and so when they came to America they copied the kinds of foods those people had eaten. In Ireland the elite were the Protestants, and very hated, so they didn't have a model of food to follow. Instead of developing a strong food culture like the Italians and the Jews, the Irish developed a strong drinking culture.

I'm sorry I can't remember the title or the author of the book, and I don't know how to find it out again.