Study on Photodegradation Mechanism and Kinetics of Vitamin A and Derivatives under Ultraviolet Irradiation

Vitamin A and its derivatives, including retinol (RE), retinyl acetate (RA), and retinyl palmitate (RP), are widely used in the food industry. However, their poor photostability limits their applications. This study investigated the photodegradation of RE, RA, and RP under ultraviolet (UV) irradiation and proposed two strategies to enhance their stability. All three compounds underwent isomerization to the 9-cis forms. RE degraded mainly via a free radical chain reaction, whereas RA and RP predominantly followed an ionic photodissociation mechanism to form anhydroretinol (AR). The addition of butylated hydroxy toluene (BHT) improved RE stability, increasing its retention by 12.49% after 4 h. Using isopropyl alcohol as the solvent inhibited AR formation from RA and RP, thereby increasing their retention by 17.12% and 16.26%, respectively, compared to ethanol. These findings provide a basis for selecting vitamin A and its derivatives and improving their UV stability in food systems.