There's an interesting NPR Planet Money article on a related topic http://www.npr.org/blogs/money/2014/06/05/319084976/why-a-pa...

It might be difficult to track the products which change labels as ingredients change.

Another interesting idea would be to see how product lines evolve. Watch as the product line is split into two or more lines to target different types of consumers (or merged for that matter), while at the same time keeping record of ingredients and other interesting info. Sounds fun!