Crystalline trehalose dihydrate, its preparation and uses

Abstract

Disclosed are a crystalline trehalose dihydrate which has an elongated crystalline structure with a proportion of the length in the c axis to that in the b axis less than 2.0, its preparation and uses. The crystal has insubstantial hygroscopicity and solidification, and satisfactory stability, free-flowing ability, and handleability; it can be easily processed without fracture in the drying and sieving steps.

We claim:  
     
         1 . A crystalline trehalose dihydrate which has an elongated crystalline structure with a proportion of the length in the c axis to that in the b axis less than 2.0.  
     
     
         2 . The crystalline trehalose dihydrate of  claim 1 , which has a proportion of the length in the c axis to that in the a axis less than 5.0.  
     
     
         3 . The crystalline trehalose dihydrate of  claim 1 , which has the length of the c axis of at least 3 mm and a polyhedron crystalline structure selected from the group consisting of deca- to icosa-hedral crystalline structures.  
     
     
         4 . The crystalline trehalose dihydrate of  claim 1 , which has a crystallinity of at least 80% when determined on powdery X-ray diffraction analysis.  
     
     
         5 . The crystalline trehalose dihydrate of  claim 1 , which has an intrusion disruptive strength of 3.5 to 4.3 kg when determined on a rheometer.  
     
     
         6 . A process for producing the crystalline trehalose dihydrate of claims  1 , which comprises the steps of: 
 placing in a crystallizer a supersaturated aqueous trehalose solution with a trehalose concentration of at least 98 w/w %, on a dry solid basis;    coexisting a crystalline trehalose dihydrate as a seed crystal;    growing the crystalline trehalose dihydrate by cooling the mixture gradually to control the supersaturation degree to a level of less than 1.15; and    separating and drying the resulting mixture to collect the grown crystalline trehalose dihydrate.    
     
     
         7 . The process of  claim 6 , wherein said crystallizer is a cylindrical rotatory crystallizer.  
     
     
         8 . The process of  claim 6 , wherein the growing step of crystalline trehalose dihydrate is carried at a temperature of about 20 to about 90° C.  
     
     
         9 . A process for producing a composition, which comprises a step of incorporating the crystalline trehalose dihydrate of  claim 1  into a material product to be incorporated with the crystal.  
     
     
         10 . The process of  claim 9 , which is a sweetener, candy fluff, baked confectionery, or alcoholic beverage with fruit.  
     
     
         11 . A method for growing said crystalline trehalose dihydrate of  claim 1 , which comprises the steps of: 
 placing in a crystallizer a supersaturated aqueous trehalose solution with a trehalose concentration of at least 98 w/w %, on a dry solid basis;    coexisting a crystalline trehalose dihydrate as a seed crystal; and    growing the crystalline trehalose dihydrate by cooling the mixture gradually to control the supersaturation degree to a level of less than 1.15.    
     
     
         12 . The method of  claim 11 , wherein an about 0.01 to about 20 w/w % of said crystalline trehalose dihydrate of  claim 1 , on a dry solid basis, is used as the seed crystal to the trehalose in the supersaturated aqueous trehalose solution.