Augustin-Pierre Dubrunfaut (1797-1881) was a French industrialist and chemist to whom we owe the discovery of mutarotation, d-fructose and maltose, the true nature of invert sugar, the mode of action of diastase and invertase, the application of osmosis to the purification sugar, the large-scale manufacture of ethanol from sugar beets, etc. Dubrunfaut used the Soleil polarimeter to discover the change of the rotatory power of aqueous glucose with time and temperature and to prove that invert sugar was composed of one-half of an equivalent of dextro monorotatory glucose and one-half equivalent of levo liquid sugar (levulose), which could be separated by simple procedures. He demonstrated that lactose also presented the phenomenon of mutarotation. Dubrunfaut analyzed in detail the phenomenon of osmosis, discovered by Dutrochet, and proved that dialysis was a special case of it. This claim brought a bitter discussion with Thomas Graham. He showed that exosmosis could be used to purify sugar very simply. Dubrunfaut claimed that malt diastase was a mixture of compounds, which included the real agent (maltose) altered or modified. Maltose could be economically fabricated in a brewery by precipitation with tannin. He also studied in detail the carbohydrate inuli
