The effect of light on the oxidative stability of phenolic compound from mango (Mangifera indica cultivar ChokAnan)seed kernelextract and its encapsulated product was determined by absorptivity in the Ultraviolet (UV) spectrum and by total phenolic content induced with white fluorescent lamp (28 watt) intensity over a 1, 3, 6, 24 and 48 h period. Maximum UV absorptive at 276nm of mango seed extract highly increased during light exposure more than the others. While, encapsulation of the extract showed the shoulder at 252 and 321 nm, the strongest UV absorption change was obtained at 276 nm from 0.625 to 1.054 after 48 hours of photo induction. Total phenolic content of samples showed a significant difference in the initial stage of photoinduced (16 hours), but after this time, the total phenolic content slowly decreased. However, the phenolic content of extract was more highly decreased than that of encapsulated product. The correlation of maximum UV absorption change valuesand total phenolics decreasing was highly related (r = 0.71). These results showed that UV absorption is a simply tool for photooxidation monitoring in quality control of mango seed kernel extract and its encapsulation.