Constituents and their sweetness of food additive enzymatically modified licorice extract

Enzymatically modified licorice extract (EMLE) is a natural sweetener, which is prepared with cyclodextrin glucanotransferase. It is used because of its unique properties such as higher solubility and better taste than those of licorice extract. In the present paper, the structures of six major constituents isolated from EMLE were determined, and their sweetness was studied. The isolated compounds were glycyrrhizin (1), 3-O-[beta-D-glucuronopyranosyl-(1-->2)-beta-D-glucuronopyranosyl]liquiritic acid (2), and their derivatives glucosylated at the C-4 position of the terminal glucuronopyranose with additional one (3 and 4, respectively) and two (5 and 6, respectively) glucose moieties. Compounds 1 and 2 are the major and minor sweet constituents in licorice extract, respectively. Compounds 3-6 are new compounds isolated for the first time. Compound 2 was sweeter than compound 1. Interestingly, compound 3, which is a monoglucosylated derivative of compound 1, was sweeter than compound 4. The sweetness of both compounds was lower than that of the parent compounds, while the lingering sweet aftertaste was markedly improved. Compounds 5 and 6, which have two additional glucose moieties, showed only slight sweetness.