Abstract: A highly safe and highly heat-resistant L-rhamnose isomerase usable in the food industry and the production thereof are disclosed. The L-rhamnose isomerase is derived from a microorganism belonging to the genus Enterobacter, has a subunit molecular mass of 47 kDa as measured by SDS-PAGE, and has the following substrate specificities (A) isomerase activity that recognizes and reacts with a CHO group at C1 and an OH group at C2 of an aldose to convert the CHO group at C1 into an OH group and the OH group at C2 into a CO group, or recognizes and reacts with an OH group at C1 and a CO group at C2 of a ketose to convert the OH group at C1 into a CHO group and the CO group at C2 into an OH group; and (B) reactivity with L-rhamnose, L-lyxose, L-mannose, D-allose, D-ribose, and L-talose.

Abstract: To provide a ketose 3-epimerase that can be used in the food industry and is highly safe, highly active, and heat resistant, a microorganism that produces this enzyme, and a method of producing a ketose. The present invention provides a ketose 3-epimerase that can be obtained from a microorganism belonging to the genus Arthrobacter, has a molecular mass of about 36 kDa as measured by SDS-PAGE, and has the following substrate specificities (A) and (B): (A) having an activity of epimerizing position 3 of a D- or L-ketose and preparing a D- or L-ketose corresponding thereto, and (B) having the highest epimerization activity on position 3 of D-allulose, among D- or L-ketohexoses.

Abstract: The present invention establishes a crystalline lactosucrose and provides a process for producing the crystalline lactosucrose or a syrup containing crystalline lactosucrose. Further, the present invention has its object to provide a composition, for example, a food or drink, a cosmetic, a drug or the like containing the crystalline lactosucrose. That is, the present invention provides the crystalline lactosucrose or the syrup containing crystalline lactosucrose, the process for producing the crystalline lactosucrose or the syrup containing crystalline lactosucrose, characterized by crystallizing a crystalline lactosucrose from a solution containing lactosucrose and collecting the crystalline lactosucrose, and the use thereof.