Castillo-Luna Ana, Miho Hristofor, Ledesma-Escobar Carlos A, Priego-Capote Feliciano
Department of Analytical Chemistry, Campus of Rabanales, University of Córdoba, 14014 Córdoba, Spain.
Chemical Institute for Energy and Environment (IQUEMA), Campus of Rabanales, University of Córdoba, 14014 Córdoba, Spain.
Foods. 2023 Jul 12;12(14):2684. doi: 10.3390/foods12142684.
Olive tree vegetal materials are considered a powerful source for the isolation of bioactive compounds-mainly phenols and triterpenic acids. However, the high humidity content of them reduces their preservation and extractability to a liquid solvent. Accordingly, a drying step is crucial to homogenize the material and to obtain an efficient extraction. We studied the influence of the drying process on the extraction efficiency of bioactive compounds from olive vegetal material. For this purpose, we evaluated the effects of four drying processes on the solid-liquid extraction of bioactive compounds from two by-products, olive leaves and pomace, and olive fruits harvested from two cultivars, Alfafara and Koroneiki. Infrared-assisted drying (IAD) was the most suited approach to obtain extracts enriched in oleuropein from leaves (28.5 and 22.2% dry weight in Alfafara and Koroneiki, respectively). In the case of pomace, lyophilization and microwave-assisted drying led to extracts concentrated in oleacein and oleuropein aglycone, whereas IAD and oven-drying led to extracts with enhanced contents of hydroxytyrosol glucoside and hydroxytyrosol, respectively. The drying process considerably affected the chemical composition of extracts obtained from fruits. Changes in the composition of the extracts were explained essentially by the drying process conditions using auxiliary energies, temperature, and time, which promoted chemical alterations and increased the extractability of the compounds. Therefore, the drying protocol should be selected depending on the phenolic content and initial raw material.
橄榄树植物材料被认为是分离生物活性化合物（主要是酚类和三萜酸）的强大来源。然而，它们的高湿度含量降低了其保存性以及在液体溶剂中的可萃取性。因此，干燥步骤对于使材料均匀化并获得高效萃取至关重要。我们研究了干燥过程对从橄榄植物材料中提取生物活性化合物效率的影响。为此，我们评估了四种干燥过程对从两种副产品（橄榄叶和果渣）以及从两个品种（阿尔法法拉和科罗内基）收获的橄榄果实中生物活性化合物固液萃取的影响。红外辅助干燥（IAD）是从叶片中获得富含橄榄苦苷提取物的最适合方法（阿尔法法拉和科罗内基中分别为干重的28.5%和22.2%）。对于果渣，冷冻干燥和微波辅助干燥导致提取物中橄榄苦苷和橄榄苦苷苷元浓缩，而IAD和烘箱干燥分别导致提取物中羟基酪醇葡萄糖苷和羟基酪醇含量增加。干燥过程对从果实中获得的提取物的化学成分有很大影响。提取物组成的变化基本上由使用辅助能量、温度和时间的干燥过程条件来解释，这些条件促进了化学变化并提高了化合物的可萃取性。因此，应根据酚类含量和初始原料选择干燥方案。
