Subject: Why do carbohydrates supplements require a certain time to begin working?

I am doing a Senior Project at my school and in order to help prove my 
hypothesis I need to find out why carbohydrate supplements like PowerGel, GU, 
and ClifShot are recommended to be taken 30-45 mintues before exercise.  From 
my last response from Steve Denham in Animal Agriculture he said that with 
disaccharides it takes maybe ten minutes.  If this is true why don't the back 
of the packets reccomend that they are taken ten minutes before exercise begins.
Thank you

Re: Why do carbohydrates supplements require a certain time to begin working?