Photostability study of natural high-potency sweetener monatin in a model beverage system and characterisation of the degradation products

Prevention of degradation of the natural high potency sweetener (2R,4R)-monatin in mock beverage solutions

“…As monatin does not absorb significantly at >310 nm, these data suggest that secondary products, with significant absorption bands at wavelengths in the near UV (>320 nm) and visible regions, play a significant role in driving the later stages of oxidation. This is consistent with the known formation of yellow/brown coloured materials on extensive oxidation of monatin and other Trp-derived materials ( Upreti et al, 2012). These findings support the use of optically opaque or coloured (yellow/brown/green) packaging as an approach to limit monatin degradation.…”

“…The latter mechanisms involve multiple reactive intermediates ( 1 O 2 , H 2 O 2 , organic peroxides, hydroxyl radicals) and leads to generation of a wide spectrum of products (Storkey et al, 2014;Upreti et al, 2012). These reactions result in a loss of parent monatin, with corresponding loss of sweetness, and the formation of materials with off-odours and unpleasant taste; a reaction scheme has recently been proposed that accounts for the formation of most of these products (Storkey et al, 2014).…”

“…The wavelength of the light illuminating mock beverage samples has been reported previously to influence the extent of monatin photo-oxidation (Evans & Goulson, 2012;Upreti et al, 2012), thus the effects of a range of light filters with different absorption characteristics were examined. Mock beverage solutions of monatin were illuminated (as above) in PET bottles that were either optically transparent at wavelengths >330 nm, that contained a <390 nm absorbance cut-off filter in the plastic, or were green in colour.…”

“…In addition, monatin has been described as having a remarkably clean taste (Abraham et al, 2005). Stability studies have shown that exposure of mock beverage solutions containing monatin to long-term UV/visible photolysis results in a loss of sweetness and the formation of unpleasant flavours and aromas (Storkey, Pattison, Gaspard, Hagestuen, & Davies, 2014;Upreti et al, 2012). Prevention of such degradation is therefore a key consideration in the use of this compound.…”

“…1) and oxidative pathways (Storkey et al, 2014;Upreti et al, 2012). Recent studies using UHPLC, LC-MS/MS and peroxide assays have demonstrated that degradation is accelerated by both UV/visible light, and the presence of trace transition metal ions.…”