A LED tube includes a translucent or fluorescent tube of substantially the shape and size of a fluorescence tube, inside which one or more LED components and a current control unit are installed. Additionally, four distinct crystal polymorphic forms of rebaudioside B are described, as well as methods for converting from one crystal polymorphic form of rebaudioside B to another crystal polymorphic form of rebaudioside B. After sintering, a billet is subjected to induction heating and hot extrusion to form a square pipe.