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 °C/8 h dark at 15 °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 TBARs450 formation. Instead, acetaldehyde, nonanal, lactose, decanal, t-cinnamaldehyde, octanal, limonene, and lactic acid favor TBARs530 formation. The interference of volatile compounds in the TBARs assay is much higher in BO.