I don't have time to refresh myself on Storable, but IIRC it dumps the data to text. A BLOB is a Binary Large OBject -- if you are storing text, and not binary data, then a TEXT element is probably better.

However, you should be able to use a BLOB, but check to make sure your encoding is the same on the way in and on the way out. MySQL can "cast" the encoding for a client depending on how it is configured.