What is the underlying representation of BLOB data when I export it?
If you use mysqldump, you can specify the hexadecimal format for BLOB data

mysqldump -u... -p... --hex-blob --all-databases ...


Here is the help on hex-blob in mysqldump

$ mysqldump --help | grep -A 1 "blob" | head -2
  --hex-blob          Dump binary strings (BINARY, VARBINARY, BLOB) in
                      hexadecimal format.