HIGH-PURITY GALACTOOLIGOSACCHARIDES AND USES THEREOF
Disclosed herein are high-purity galactooligosaccharide compositions, methods of producing high-purity galactooligosaccharides, food products and method of preparing food products comprising a high-purity galactooligosaccharide composition.
1 . A method of producing galactooligosaccharide comprising catalyzing the conversion of lactose to galactooligosaccharide using a suitable enzyme; and chromatographically purifying the galactooligosaccharide using an ion exchange resin comprising a K + counter ion.
2 . The method of claim 1 , wherein the enzyme is a β-galactosidase.
3 . The method of claim 2 , wherein the β-galactosidase is derived from Cryptococcus laurentii, Aspergillus oryzae, Aspergillus nigar; Bacillus circulans, Bacillus subtilis, Bacillus licheniformis, Lactobacillus bulgaricus, Streptococcus thermophilus, Bullera singularis, Bifidobacterium breve, Bifidobacterium longum, Bifidobacterium infantis, Bifidobacterium bifidum, Lactococcus lactis, Candida pseudotropicalis , or Kluyveromyces lactis.
4 . The method of claim 3 , wherein the β-galactosidase is derived from Bacillus circulans.
5 . The method of claim 1 , wherein the ion exchange resin comprising a K + counter ion is an acidic cation exchange resin with cross-linked polystyrene matrix and sulfonate functional groups.
6 . The method of claim 1 , further comprising the step of passing the galactooligosaccharide through atleast one ion-exchange column selected from a cation column with strongly acidic cation exchange resin, an anion column with a basic anion exchange resin, and a mixed bed column comprising a combination of both strongly acidic and strongly basic resins.
7 . The method of claim 6 , wherein the basic anion exchange resin is selected from a weakly basic anion exchange resin or an intermediate basic anion exchange resin.
8 . The method of claim 6 , comprising a three-column ion-exchange purification process.
9 . The method of claim 8 , wherein the three-columns comprise a cation column with strongly acidic cation exchange resin, an anion column with a basic anion exchange resin; and a mixed bed column comprising a combination of both strongly acidic and strongly basic resins.
10 . The method of claim 9 , wherein the basic anion exchange resin is selected from a weakly basic anion exchange resin or an intermediate basic anion exchange resin.
11 . The method of claim 8 , wherein the three-column ion-exchange process is conducted prior to the chromatographic purification step.
12 . The method of claim 1 , further comprising the additional step of decolorizing the galactooligosaccharide solution with activated carbon prior to the ion-exchange purification step.
13 . The method of claim 1 , wherein an aqueous solution of lactose is contacted with the enzyme.
14 . The method of claim 13 , wherein the concentration of lactose in the solution ranges between about 5% and about 90%.
15 . The method of claim 1 , wherein the galactooligosaccharide composition comprises no more than about 10% by weight of carbohydrates other than galactooligosaccharide.
16 . The method of claim 1 , wherein the method is included in a process for producing a baby food, an infant formula, a beverage, a yogurt, or a dietary supplement.
17 . A method for producing high-purity galactooligosaccharide, the method comprising:
(a) contacting lactose with a suitable enzyme under mildly acidic conditions to produce galactooligosaccharide;
(b) decolorizing galactooligosaccharide with activated carbon;
(c) passing galactooligosaccharide through one or more ion-exchange columns selected from a cation column with strongly acidic cation exchange resin, an anion column with a basic anion exchange resin, and a mixed bed column comprising a combination of both strongly acidic and strongly basic resins; and
(d) chromatographically purifying the galactooligosaccharide using an ion exchange resin comprising a K + counter ion.
18 . A galactooligosaccharide composition obtained by the process of claim 17 .
19 . The galactooligosaccharide composition of claim 18 comprising, as effective constituents, a mixture of one or more disaccharides, trisaccharides, tetrasaccharides and pentasaccharides.
20 . The galactooligosaccharide composition according to claim 19 , comprising from about 10% to about 25% w/v of the disaccharide, from about 30% to about 50% w/v of the trisaccharide, and from about 30% to about 45% w/v of the tetrasaccharide and higher oligosaccharides.