Storkey Corin, Pattison David I, Gaspard Dan S, Hagestuen Erik D, Davies Michael J
The Heart Research Institute, 7 Eliza Street, Newtown, New South Wales 2042, Australia.
J Agric Food Chem. 2014 Apr 16;62(15):3476-87. doi: 10.1021/jf404198w. Epub 2014 Apr 3.
The sodium, potassium, or mixed sodium/potassium salt of the naturally occurring high-potency sweetener (2R,4R)-monatin, also known by the common name arruva, degrades over time in model beverage solutions in the presence of light. By use of UHPLC, LC-MS/MS, and peroxide assays, it has been demonstrated that degradation is accelerated by UV/visible light and the presence of trace metal ions. Data are presented that are consistent with a role for singlet oxygen (¹O₂), free radicals, and peroxides (both H₂O₂ and organic peroxides) in monatin oxidation. Separation of degradation products by UHPLC/HPLC or LC-MS/MS provided evidence for the formation of hydroxylated and peroxide species formed on the indole ring (mass increases 16 and 32, respectively) as well as multiple ring and side-chain oxidation and scission products. Model oxidation systems using the photosensitizer Rose Bengal as a source of ¹O₂ support the proposed photodegradation pathways.
