The enzyme inulin fructotransferase (DFA-III-forming) (EC 4.2.2.18) catalyzes the following process: Produces α-D-fructofuranose β-D-fructofuranose 1,2′:2,3′-dianhydride (DFA III) by successively eliminating the diminishing (2→1)-β-D-fructan (inulin) chain from the terminal D-fructosyl-D-fructosyl disaccharide. (wikipedia.org)
This enzyme, like EC 4.2.2.17 [inulin fructotransferase (DFA-I-forming)] and EC 4.2.2.18 [inulin fructotransferase (DFA-III-forming)] eliminates the fructan chain from the terminal disaccharide leaving a difructose dianhydride. (enzyme-database.org)