Exposure of retinyl palmitate (RP) to ultraviolet radiation can lead to its photo-degradation and loss of biological activity. Therefore, there is a demand to explore new approaches to protect RP in an easy, economical and efficient way. The objective of this study was to explore the role of policosanol oleogels (PCOs) in the protection of RP from photodegradation. UV-blocking action was tested by placing a layer of PCO as a barrier between a UVA (365 nm) source and 1% RP in soybean oil. Effects of structural characteristics of PCOs cooled at different rates on RP photostability were also studied. The ability of PCOs to prevent radical-mediated reactions was assessed by measuring oil oxidative stability over storage time at 40 °C. The remaining % RP was measured by HPLC during 4 days of UVA irradiation. PCO blocked energy absorption from UVA and further dampened the UVA mediated ionic photodissociation and free radical reactions due to matrix immobilization. After 4 days of UV exposure, photodegradation of RP was reduced by 64% when a PCO layer was used as a barrier. Peroxide values (PV) and p-anisidine values (p-A.V.) of soybean oil (SO) were significantly higher than those of PCOs over storage time. Cooling rate processing played a significant role in RP protection; the faster the cooling rate, the higher the RP photostability. This study demonstrated that the protective mechanism of RP in PCOs is a combined effect of physical UV-barrier action, molecular immobilization and inhibition of the free radical-mediated reaction.

中文翻译：

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超分子多二十烷醇油凝胶在保护棕榈酸视黄酯免受光降解中的作用

棕榈酸视黄酯 (RP) 暴露于紫外线辐射会导致其光降解和生物活性丧失。因此，需要探索以简单、经济和有效的方式保护 RP 的新方法。本研究的目的是探讨多二十烷醇油凝胶 (PCO) 在保护 RP 免受光降解方面的作用。通过在 UVA (365 nm) 源和豆油中的 1% RP 之间放置一层 PCO 作为屏障来测试 UV 阻挡作用。还研究了以不同速率冷却的 PCO 的结构特征对 RP 光稳定性的影响。PCO 防止自由基介导反应的能力是通过测量油在 40 °C 下储存时间的氧化稳定性来评估的。在 4 天的 UVA 照射期间，通过 HPLC 测量剩余的 % RP。PCO 阻止了来自 UVA 的能量吸收，并进一步抑制了由于基质固定导致的 UVA 介导的离子光解离和自由基反应。在紫外线照射 4 天后，当 PCO 层用作屏障时，RP 的光降解减少了 64%。过氧化值 (PV) 和随着储存时间的推移，大豆油 (SO) 的对茴香胺值 ( p -AV) 显着高于 PCO 的值。降温速率处理在RP保护中发挥了重要作用；冷却速度越快，RP 光稳定性越高。该研究表明，RP 在 PCOs 中的保护机制是物理 UV 屏障作用、分子固定和抑制自由基介导反应的综合作用。