The rebaudioside D-rich steviol glycoside preparation (~95% rebaudioside D) is produced via an enzymatic conversion process using a strain of Pichia pastoris that has been genetically modified to express UDPglucosyltransferase EUGTll. In the first stage of manufacturing, a steviol glycoside primary extract from the leaves of 5. rebaudiana Bertoni containing 55±5% of rebaudioside A is produced according to the methodology outlined in the Chemical and Technical Assessment (CTA) published by the Food and Agriculture Organization (FAO)/JECFA for steviol glycosides (FAQ, 2016). In the next step, the steviol glycoside primary extract is further purified to a purity of ~95% rebaudioside A through crystallization, also consistent with the CTA methodology. In the third stage, the P. pastoris production strain is subjected to a fermentation step to express the UGT-glucosyltransferase EUGTll, which is used to catalyze the conversion of the high-purity rebaudioside A extracted from 5. rebaudiana Bertoni to rebaudioside D. In the last stage, the rebaudioside D solution is purified and concentrated according to the methodology described in the steviol glycoside CTA, yielding a final product that contains ~95% rebaudioside D.
www.fda.gov
