Process for the preparation of fructosyl disaccharides

Claim 1

A process for the preparation of a halodeoxy sucrose of galactosucrose derivative of the formula ##STR5## in which A represents a hydrogen atom or the group CH 2 X, where X represents a hydrogen atom, or a hydroxy or alkoxy group and Y represents a halogen atom, comprising reaction of an aldose of the formula ##STR6## in which A represents a hydrogen atom or the group CH 2 X, where X represents a hydrogen atom or an alkoxy group or a protected hydroxy group, with a fructosyldi or oligo-saccharide in the presence of a fructosyltransferase to obtain a compound of the general formula ##STR7## in which A is as defined for formula II, separating said compound of formula III; halogenating the compound of formula III and, for a compound of the formula I in which A represent CH 2 X and X represents a hydroxy group, de-protecting the protected hydroxy group wherein said fructosyltransferase is an enzyme isolated from bacteria which hydrolizes a donor fructosyl oligosaccharide or disaccharide containing an unsubstituted-fructosyl ring attached to the anomeric carbon atom of an aldose by a (1→2) linkage and transfers the fructosyl moiety so released to an acceptor aldose to yield a fructosyl disaccharide as the main product, said enzyme being capable of forming 6-substituted sucrose derivatives as the main product when the acceptor aldose is a 6-substituted glucose, said enzyme producing no significant amounts of alcohol precipitatable oligo- or polyfructoses in the absence of an aldose acceptor, said enzyme having a Km for sucrose of at least 0.1M in the absence of an aldose acceptor and being free from invertase activity, said enzyme being unaffected by the presence of surfactants, having an optimum activity at about 30° C. and being active for at least 20 minutes at up to 45° C.