Excel 2007 : Converting "mm min ss s" time format to "hh:mm:ss"

Hi,
Hope you guys can help.

I have the following data:

18 min 56 s

15 min 52 s

14 min 50 s

Is there a way to convert it to:

00:18:56

00:15:52

00:14:50

?

Thanks!
David