Selective transformation of fructose and high fructose content biomass into lactic acid in supercritical water

•Fructose was converted into pyruvaldehyde with a yield of 89% in supercritical water.•Aldoses produce C-2 molecules while ketoses produce C-3 molecules in SCW reactions.•Natural biomass was transformed into lactic acid in a SCW medium.•Sodium hydroxide was a promising catalyst for the production of lactic acid.