Abstract: A method for preparing high-purity crystalline lactulose and the product obtained by the method, which comprises crystallization from aqueous solutions at a temperature of 5.degree.-40.degree. C., the starting aqueous solution having a lactulose concentration of 50-80% w/w, a lactose concentration of less than 5% of the lactulose concentration by weight, a galactose concentration of less than 5% of the lactulose concentration by weight, and a concentration of other sugars of less than 4% of the lactulose concentration by weight.

Abstract: A process for preparing high-purity lactulose by the following stages:(a) diluting with water to a concentration of 15-25% a syrup containing 45-55% of lactulose and having a lactulose content on a dry substance basis of between 74 and 82% w/w;(b) pretreating the diluted syrup with bromine or bifunctional boron resins;(c) treating the pretreated syrup from stage (b) with ion exchange resins of strong anion type under conditions such that the pH of the percolated syrup is between 8 and 10.

Abstract: Stable boron resins of high selective absorbent power and their production process. Said boron resins consist of a polyacrylic matrix functionalized with quaternary ammonium groups, an epoxy group and phenylboric groups in accordance with general formula (I): ##STR1## in which P , R.sub.1, R.sub.2, R.sub.3, R.sub.4 and X.sup.- are as defined in the text.The resins are prepared by reacting an amine resin with an epihalohydrin and condensing the reaction product with a suitable boroxin.The resins of formula (I) can be used for separating sugars, in particular for purifying lactulose. They have greater selective power than currently known boron resins.

Abstract: Stable boron resins of high selective absorbent power and their production process. Said boron resins consist of a polyacrylic matrix functionalized with quaternary groups, an epoxy group and phenylboric groups in accordance with general formula (I): ##STR1## in which P, R, R.sub.1, R.sub.2, R.sub.3, Y and X.sup.- are as defined in the text.The resin is prepared by condensing an acrylic resin with an epihalohydrin and then with a halide or hydroxide of an oxiphenyl-aminophenyl- or thiophenyl-boroxin or their alkyl derivatives.Compared with similar currently known resins, the resins of formula (I) have improved selectivity in sugar separation. They can be used for purifying lactulose.