Thiobarbituric acid reactive substances in flavored phytosterol-enriched drinking yogurts during storage: formation and matrix interferences

The aim of this study was to evaluate the level of thiobarbituric acid reactive substances (TBARs) in flavored phytosterol-enriched drinking yogurts during storage, with particular attention to matrix interference. Two phytosterol-enriched drinking yogurts (with white vanilla-WV and blood orange-BO) were kept under controlled conditions (16 h light at 25 A degrees C/8 h dark at 15 A degrees C) for 64 h. During the TBARs assay, a yellow complex was formed. The UV-Vis spectra showed two absorption bands around 450 and 530 nm, respectively. In both flavored phytosterol-enriched drinking yogurts, the more intense absorption was around 450 nm. In conclusion, the development of TBA adducts leads to a higher overestimation of TBARs at 450 nm. The study of TBA reaction with some of the matrix compounds shows that propanal, pentanal, hexanal, p-anisaldehyde, and vanillin favor TBARs(450) formation. Instead, acetaldehyde, nonanal, lactose, decanal, t-cinnamaldehyde, octanal, limonene, and lactic acid favor TBARs(530) formation. The interference of volatile compounds in the TBARs assay is much higher in BO.