Well to make sugar from biomass you'd prob have to break down cellulose.
Cellulose is a condensation polymer. It is made up Beta glucose molecules linked together.
In order to break down the cellulose and obtain glucose (sugar) there are two possible methods you can use:
There are 2 processes for breaking cellulose into glucose: -
1. Digestion by cellulose enzymes-
These enzymes exist in bacteria and certain fungi. The process can be performed industrially by first treating finely ground cellulose- containing material [such as grain husks and stalks, bagasse and old newspapers] with NaOH to swell the cellulose fibre, then digesting them with cellulase enzymes to produce a solution of glucose.
2. Digestion with strong acid-
This involves heating a suspension of cellulose- containing material with moderately concentrated aqueous sulfuric acid solution which breaks cellulose into glucose. Insoluble matter, particularly lignin from wood pulp, is filtered off and many impurities are removed. Then the acid is neutralized to produce a solution of glucose.
Hope this helps...