NOVELTY - Method (I) for producing readily saccharifiable carbohydrate-enriched biomass, comprises: (a) providing lignocellulosic biomass comprising lignin; (b) contacting the biomass with an aqueous solution comprising ammonia, to produce an ammonia-treated biomass; and contacting ammonia-treated biomass with a gas comprising ozone at temperature of 0-50 degrees C.    USE - The method is useful for producing readily saccharifiable carbohydrate-enriched biomass which is saccharified with an enzyme consortium to produce fermentable sugars, where the sugars are fermented to produce target products (all claimed), where: the target products include: alcohols (e.g. arabinitol, butanol, ethanol, glycerol, methanol, 1,3- propanediol, sorbitol and xylitol); organic acids (e.g. acetic acid, adipic acid, ascorbic acid, citric acid, 2,5-diketo-D-gluconic acid, formic acid, fumaric acid, gluconic acid, glucuronic acid, glutaric acid, 3-hydroxypropionic acid, itaconic acid, lactic acid, malic acid, malonic acid, oxalic acid, propionic acid, succinic acid and xylonic acid); ketones (e.g. acetone); amino acids (e.g. aspartic acid, glutamic acid, glycine, lysine, serine and threonine); and gases (e.g. methane, hydrogen, carbon dioxide and carbon monoxide); the potential coproducts e.g. multiple organic products are produced; and the fermentable carbohydrate, lignin-rich residues remaining after pretreatment and fermentation is converted to lignin-derived chemicals, chemical building blocks or used for power production.    ADVANTAGE - The method: has high selectivity for fragmenting and removing lignin from the biomass while leaving the carbohydrates largely intact; produces carbohydrate enriched biomass, highly susceptible to enzymatic saccharification, in a cost effective process; and provides good xylose recovery through saccharification. In the method: the separation or washing of the biomass after ozone treatment, to physically remove the oxidized and fragmented lignin is not necessary and minimizes sugar loss during lignin oxidation and fragmentation, which is of economic benefit; and the ozone treatment is performed on solid biomass or aqueous suspension of biomass which offers opportunity for overall process simplification and economic benefit.    DETAILED DESCRIPTION - Method (I) for producing readily saccharifiable carbohydrate-enriched biomass, comprises: (a) providing lignocellulosic biomass comprising lignin; (b) contacting the biomass with an aqueous solution comprising ammonia, where the ammonia is present at a concentration (less than 12 wt.% relative to dry weight of biomass) at least sufficient to maintain alkaline pH of the biomass-aqueous ammonia mixture and the dry weight of biomass is at high solids concentration of at least 15 wt.% relative to the weight of the biomass-aqueous ammonia mixture, to produce an ammonia-treated biomass; and contacting ammonia-treated biomass with a gas comprising ozone at temperature of 0-50 degrees C. An INDEPENDENT CLAIM is also included for method (II) for producing readily saccharifiable carbohydrate-enriched biomass, comprising: step (a) as per se; (d) contacting the biomass with a gas comprising ozone at a temperature of 0-50 degrees C and (e) contacting the ozone-treated biomass with the aqueous solution comprising ammonia to form a mixture comprising ozone-treated biomass and aqueous ammonia, where the ammonia is present at a concentration (less than 12 wt.% weight relative to dry weight of ozone-treated biomass) at least sufficient to maintain alkaline pH of the mixture and the dry weight of biomass is at high solids concentration of at least 15 wt.% relative to the weight of the mixture.