No estimate of how much food is wasted is precise, but the EPA says that 14% of landfill waste is food scraps. Waste of food packaging (contrasted with food scraps) is hard to classify, but one can assume that much of the plastic and glass in a landfill is food packaging and together they constitute 17% of landfill waste.
Food packaging is a tough area to make reductions in waste because it is part of a big process food processing and distribution. Without packaging food distribution would be wasteful indeed, and most packaging does help to preserve the food.
However, one idea to redesign food packaging caught attention because it is a novel way to think about the problem. Design packages you can eat, being done by Prof. David Edwards. He calls them WikiCells. How eating the package will affect nutrition, and whether eating the packages will do anything to reduce overeating are a few of the questions that additionally beg for research. But Edwards has illustrated how to view a problem very differently.