Kinetic study on photostability of retinyl palmitate entrapped in policosanol oleogels

• Published in: Food chemistry 2018-07, Vol.255, p.252-259
• Main Authors: Tian, Yixing, Acevedo, Nuria C.
• Format: Article
• Language: English
• Subjects: Fatty Alcohols - chemistry; Fatty Alcohols - radiation effects; Kinetics; Oleogel; Organic Chemicals - chemistry; Organic Chemicals - radiation effects; Photolysis; Photostability; Policosanol; Retinyl palmitate; Ultraviolet Rays; Vitamin A - analogs & derivatives; Vitamin A - chemistry; Vitamin A - radiation effects
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2018.02.025

•Policosanol oleogels improved the photostability of RP.•Policosanol oleogels blocked energy absorption from UVA to protect RP.•Photodegradation of RP followed a 2nd order reaction.•From the reaction kinetics, it would be possible to predict the RP photodegradation rate. Photostability of all-trans retinyl palmitate (RP) (100% bioactivity) was studied in policosanol oleogels (PCOs) (7–12% w/w policosanol in soybean oil) after UVA irradiation. RP was incorporated into PCOs at levels of 0.04%, 0.1% and 1% (w/w). PCOs efficiently protected RP from UVA-mediated degradation. Over 75% RP-activity remained in PCOs after 4 days of UVA irradiation, while 12% RP-activity remained in soybean oil. HPLC analysis showed that cis-RP was formed in liquid soybean oil after 2 days of UVA irradiation while it was absent in PCOs matrices. PCOs blocked the energy absorption from UVA and further dampened the UVA-mediated ionic photodissociation and free radical reaction due to matrix immobilization. For all samples, RP photodegradation followed a 2nd order reaction. From the reaction kinetics, it would be possible to predict the RP photodegradation rate in PCO matrices. PCOs were shown to be a promising matrix to protect RP from photodegradation.