Rodis Panayotis S, Karathanos Vaios T, Mantzavinou Antonia
Department of Food Science and Technology, Agricultural University of Athens, Iera Odos 75, Votanikos 11855, Athens, Greece.
J Agric Food Chem. 2002 Jan 30;50(3):596-601. doi: 10.1021/jf010864j.
The partition coefficient (K(p)) of the natural phenolic antioxidant compounds in the olive fruit between aqueous and olive oil phases was determined. The antioxidants of olive oil are either present in the olive fruit or formed during the olive oil extraction process. The antioxidants impart stability to and determine properties of the oil and are valuable from the nutritional point of view. The olive oil antioxidants are amphiphilic in nature and are more soluble in the water than in the oil phase. Consequently, a large amount of the antioxidants is lost with the wastewater during processing. The determination of antioxidants was performed using HPLC, and the K(p) was estimated to be from as low as 0.0006 for oleuropein to a maximum of 1.5 for 3,4-DHPEA-EA (di-hydroxy-phenyl-ethanol-elenolic acid, oleuropein aglycon). Henry's law fitted very well to the experimental data. The partition coefficients were also estimated by applying the activity coefficients of the antioxidants in the two phases using a predictive group contribution method, the UNIFAC equation. The K(p) values estimated with UNIFAC method were of the same order of magnitude but varied from the experimental values. Nevertheless, this method may be a rough predictive tool for process optimization or design. Because the K(p) values were very low, some changes in the process are recommended in order to achieve a higher concentration of antioxidants in the oil. A temperature increase may lead to increasing the partition coefficient. Also, limiting the quantity of water during oil extraction could be a basis for designing alternative processes for increasing the antioxidant concentration in the olive oil.
测定了橄榄果实中天然酚类抗氧化化合物在水相和橄榄油相之间的分配系数（K(p)）。橄榄油中的抗氧化剂要么存在于橄榄果实中，要么在橄榄油提取过程中形成。这些抗氧化剂赋予油脂稳定性并决定其性质，从营养角度来看很有价值。橄榄油抗氧化剂本质上具有两亲性，在水相中比在油相中更易溶解。因此，大量抗氧化剂在加工过程中随废水流失。使用高效液相色谱法（HPLC）测定抗氧化剂，估计橄榄苦苷的K(p)低至0.0006，而3,4 - DHPEA - EA（二羟基苯乙醇橄榄酸，橄榄苦苷苷元）的K(p)最高为1.5。亨利定律与实验数据拟合得非常好。还使用预测基团贡献法（UNIFAC方程）通过应用抗氧化剂在两相中的活度系数来估计分配系数。用UNIFAC方法估计的K(p)值在相同数量级，但与实验值有所不同。然而，该方法可能是用于工艺优化或设计的粗略预测工具。由于K(p)值非常低，建议对工艺进行一些改变以在油中获得更高浓度的抗氧化剂。温度升高可能导致分配系数增加。此外，在油提取过程中限制水量可能是设计提高橄榄油中抗氧化剂浓度的替代工艺的基础。
