Process for producing a particulate composition comprising crystalline trehalose dihydrate

1. A process for producing a particulate composition comprising crystalline α,α-trehalose dihydrate with an α,α-trehalose content of 98.0% by weight or more, on a dry solid basis, said process comprising the steps of:

allowing to act on liquefied starch an α-glycosyltrehalose-forming enzyme derived from a microorganism of the genus Arthrobacter and a trehalose-releasing enzyme derived from a microorganism of the genus Arthrobacter along with a starch debranching enzyme and a cyclomaltodextrin glucanotransferase;

allowing a glucoamylase to act on the resulting mixture to obtain a saccharide solution comprising α,α-trehalose;

precipitating crystalline α,α-trehalose dihydrate from said saccharide solution by a controlled cooling method or semi-controlled cooling method;

collecting the precipitated crystalline α,α-trehalose dihydrate by a centrifuge; and

ageing and drying the collected crystals to obtain a particulate composition comprising crystalline α,α-trehalose dihydrate;

wherein a natural or recombinant cyclomaltodextrin glucanotransferase derived from a microorganism of the genus Paenibacillus or a mutant enzyme thereof is used as said cyclomaltodextrin glucanotransferase for converting maltooligosaccharides having a glucose polymerization degree of four or lower into maltooligosaccharides having a glucose polymerization degree of five or more, by a disproportionation reaction, and to increase the α,α-trehalose content in said saccharide solution to over 86.0% by weight, on a dry solid basis, without passing through a fractionation step by column chromatography;

wherein said controlled cooling method is a cooling method where the liquid temperature “T” at the time “t” is basically expressed by the formula:

T=T 0 −( T 0 −T f )( t /τ) 3 ,

wherein “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;

wherein said semi-controlled cooling method is a cooling method, where the liquid temperature “T” is allowed to linearly or stepwisely decrease against the time “t” in order to keep the variation (T 0 −T m ) of the liquid temperature “T” at the point of “t=τ/2” to be at least 5% but less than 50% of the total temperature change (T 0 −T f ), wherein “T m ” is the liquid temperature at time “t=τ/2”; and

wherein said particulate composition has a degree of crystallinity for crystalline α,α-trehalose dihydrate of 90.0% or higher, when calculated based on its powder X-ray diffraction profile.

2. The process of claim 1 , wherein said microorganism of the genus Paenibacillus is of the species Paenibacillus illinoisensis, Paenibacillus pabuli , or Paenibacillus amylolyticus.

3. The process of claim 1 , wherein said cyclomaltodextrin glucanotransferase is an enzyme that has the following partial amino acid sequences of (a) to (d):

(a)

Gly-Ser-X 1 -Ala-Ser-Asp;

(b)

Lys-Thr-Ser-Ala-Val-Asn-Asn;

(c)

Lys-Met-Pro-Ser-Phe-Ser-Lys;

and

(d)

Val-Asn-Ser-Asn-X 2 -Tyr;

wherein X 1 means Ala or Ser and X 2 means Ala or Thr, respectively.

4. The process of claim 1 , wherein said cyclomaltodextrin glucanotransferase is the one that has an amino acid sequence of SEQ ID NO: 1, 2, 3, 12 or 13.