There are articles which say that up to 60% of sushi is mislabeled. I believe the current verification is DNA based, but I would bet a good fish monger could tell most of the time just by looking. Image quality/consistency would probably be a huge impediment for mobile devices, but otherwise it seems like a pretty standard image classification problem.

I saw some papers in Computers and Electronics in Agriculture journal published during 2012-2013. This is an state-of-the-art technology attracting some researchers to develop APPs for Aro-Food sector. Since it is new in Agro-Food technology, I suggest to search for documents with similar applications in industry.