Process for producing a particulate composition comprising anhydrous crystalline 2-O-alpha-D-glucosyl-L-ascorbic acid
The invention provides a process for enabling the production of a particulate composition containing anhydrous crystalline ascorbic acid 2-glucoside that does not significantly cake even when the production yield of ascorbic acid 2-glucoside does not reach 35% by weight. The process for producing a particulate composition containing anhydrous crystalline ascorbic acid 2-glucoside, which comprises allowing a CGTase to act on a solution containing either liquefied starch or dextrin and L-ascorbic acid and then allowing a glucoamylase to act on the resulting solution to obtain a solution with an ascorbic acid 2-glucoside production yield of at least 27%, purifying the obtained solution to increase the ascorbic acid 2-glucoside content to a level of over 86% by weight, precipitating anhydrous crystalline ascorbic acid 2-glucoside by a controlled cooling method or pseudo-controlled cooling method, collecting the precipitated anhydrous crystalline ascorbic acid 2-glucoside, and ageing and drying the collected anhydrous crystalline ascorbic acid 2-glucoside.
1. A process for producing a particulate composition comprising anhydrous crystalline 2-O-α-D-glucosyl-L-ascorbic acid, said process comprising the following steps (a) to (e):
(a) incubating an aqueous solution comprising cyclomaltodextrin glucanotransferase, ascorbic acid, and either liquefied starch or dextrin to obtain a reaction mixture and then further incubating the reaction mixture along with glucoamylase to obtain a resulting solution with a 2-O-α-D-glucosyl-L-ascorbic acid content of at least 27% but less than 35% by weight, on a dry solid basis;
(b) purifying the resulting solution comprising 2-O-α-D-glucosyl-L-ascorbic acid to give a purified solution with a 2-O-α-D-glucosyl-L-ascorbic acid content of over 86% by weight, on a dry solid basis;
(c) crystallizing 2-O-α-D-glucosyl-L-ascorbic acid from the purified solution in the presence of seed crystals in the amount of 0.1% to 5% (w/v) by a controlled cooling method or pseudo-controlled cooling method;
(d) collecting the crystallized anhydrous 2-O-α-D glucosyl-L-ascorbic acid; and
(e) ageing and drying the crystals to obtain the particulate composition which contains over 98.0% but below 99.9% by weight of 2-O-α-D-glucosyl-L-ascorbic has a degree of crystallinity of at least 90%, when calculated based on the powder X-ray diffraction profile of the particulate composition, and has a reducing power of the whole particulate composition of less than 1% by weight;
wherein, in step (c), said controlled cooling method is defined by the equation T=T 0 −(T 0 −T f )(t/τ) 3 , where “T” is the liquid temperature at the time “t”, “τ” is the operation time established for a crystallization step, “T 0 ” is the liquid temperature at the initiation of crystallization, and “T f ” is the targeted liquid temperature at the termination of crystallization; and said pseudo-controlled cooling method is defined by the equation above, where the liquid temperature “T” at the time “t” is allowed to linearly or stepwisely decrease with the time “t” in order to keep the variation (T 0 −T m ) of the liquid temperature “T” at time “t=τ/2” to be at least 5% but less than 50% of the total temperature change (T 0 −T f ), with “T m ” being the liquid temperature at time “t=τ/2”.
2. The process of claim 1 , wherein the reaction mixture of step (a) comprises a starch-debranching enzyme.
3. The process of claim 1 , wherein step (b) comprises purifying the resulting solution by anion exchange chromatography, and by simulated-moving-bed column strong-acid cation exchange chromatography.
4. The process of claim 1 , wherein said cyclomaltodextrin glucanotransferase comprises the partial amino acid sequences (a) to (d):
(SEQ ID NO: 9)
(a) Asn-Glu-Val-Asp-X1-Asn-Asn;
(SEQ ID NO: 10)
(b) Met-Ile-Gln-X2-Thr-Ala;
(SEQ ID NO: 11)
(c) Pro-Gly-Lys-Tyr-Asn-Ile;
and
(SEQ ID NO: 12)
(d) Val-X3-Ser-Asn-Gly-Ser-Val,
wherein X 1 is Pro or Ala, X 2 is Ser or Asp, and X 3 is Ser or Gly, respectively.
5. The process of claim 1 , wherein said cyclomaltodextrin glucanotransferase is a Geobacillus stearothermophilus or Thermoanaerobacter thermosulfurigenes cyclomaltodextrin glucanotransferase.
6. The process of claim 1 , wherein said cyclomaltodextrin glucanotransferase comprises any one of the amino acid sequences of SEQ ID NOs:1, 3, 4 and 5.
7. The process of claim 1 , wherein the obtained particulate composition contains L-ascorbic acid and/or D-glucose, wherein said L-ascorbic acid is less than 0.1% by weight of the dry solid.
8. The process of claim 1 , wherein the 2-O-α-D-glucosyl-L-ascorbic acid content in the resulting solution obtained in step (a) is in the range of 27% to 33% by weight, on a dry solid basis.
9. The process of claim 1 , wherein the obtained particulate composition, comprising anhydrous crystalline 2-O-α-D-glucosyl-L-ascorbic acid, contains particles with a particle size of less than 150 μm in an amount of 70% by weight or higher of the composition, and particles with a particle size of at least 53 μm but less than 150 μm in an amount of 40 to 60% by weight of the composition.
10. The process of claim 1 , further comprising pulverizing the collected anhydrous crystalline 2-O-α-D-glucosyl-L-ascorbic acid to obtain the particulate composition.