Structural determination of carbohydrates(sucrose) I recently came across a question in which we have to find out the number of moles of $\ce{HIO4}$(Periodic acid) which are required for cleavage of $\ce{C-C}$ bonds in sucrose. 

I went to https://en.m.wikibooks.org/wiki/Structural_Biochemistry/Carbohydrates/Carbohydrate_Structure_Elucidation_through_Periodic_Acid_Cleavage . But this article is rather incomplete and doesnot answer the question. In general what are the things to be kept in mind in order to find out the number of moles of periodic acid required for the structural determination of carbohydrates. Any ideas?  Thanks.
First of all, lets be familiar with what per-iodic acid does to organic compounds.

It selects the carbon-carbon bonds that have either an -OH group, a =O(carbonyl) group or if it is the functional group carbon of a carboxylic acid. Both the carbons of the C-C bond must satisfy this condition. Here are some examples of the selection points of per-iodic acid:


Now that per-iodic acid has chosen the center, it cleaves the C-C bond and adds an -OH at each carbon. For every C-C bond, one per-iodic acid molecule is consumed. I am avoiding going throughout the actual mechanism to keep things simple. If any of the carbons has two -OH groups, they will spontaneously dehydrated to give a =O bond instead. For the examples shown above, the final products of the cleavage-oxidation would be:


Now, coming to your main question, the structure of sucrose would be:


By what we have seen, lets mark the C-C bonds that per-iodic acid can cleave:


Since we have 3 centers, so thats why 3 molecules of per-iodic acid are consumed per molecule of sucrose. Now you can even proceed and find out the oxidation products.

I hope this answer helps. Happy carbohydrate breaking!