Gómez-Cruz Irene, Contreras María Del Mar, Romero Inmaculada, Castro Eulogio
Department of Chemical, Environmental and Materials Engineering, Universidad de Jaén, Campus Las Lagunillas, S/N, 23071 Jaén, Spain.
Centre for Advanced Studies in Earth Sciences, Energy and Environment (CEACTEMA), Universidad de Jaén, Campus Las Lagunillas, S/N, 23071 Jaén, Spain.
Antioxidants (Basel). 2021 Nov 7;10(11):1781. doi: 10.3390/antiox10111781.
Olive-derived biomasses contain bioactive compounds with health promoting effects as well as antioxidant and sweet-tasting properties. However, their sequential extraction has not been attained. In the present study, firstly antioxidants and mannitol were extracted from exhausted olive pomace (EOP) by an eco-friendly method, ultrasound-assisted water extraction (UAWE). The amplitude (20-80%), extraction time (2-18 min) and solid loading (2-15%, /) were evaluated according to a Box-Behnken experimental design. Using the response surface methodology, the optimal conditions for extraction were obtained: 80% amplitude, 11.5% solid loading and 16 min. It enabled the multi-response optimization of the total phenolic content (TPC) (40.04 mg/g EOP), hydroxytyrosol content (6.42 mg/g EOP), mannitol content (50.92 mg/g EOP) and antioxidant activity (ferric reducing power or FRAP, 50.95 mg/g EOP; ABTS, 100.64 mg/g EOP). Moreover, the phenolic profile of the extracts was determined by liquid chromatography-UV and mass spectrometry, identifying hydroxytyrosol as the main phenolic compound and other minor derivatives could be characterized. Scanning electron microscopy was used to analyze the morphological changes produced in the cellular structure of EOP after UAWE. In addition, the chemical composition of the extracted EOP solid was characterized for further valorization. Then, a second extraction step was performed in order to extract bioactive triterpenes from the latter solid. The triterpenes content in the extract was determined and the effect of the previous UAWE step on the triterpenes extraction was evaluated. In this case, the use of ultrasound enhanced the extraction of maslinic acid and oleanolic acid from pelletized EOP with no milling requirement. Overall, UAWE can be applied to obtain antioxidant compounds and mannitol as first extraction step from pelletized EOP while supporting the subsequent recovery of triterpenic acids.
橄榄衍生生物质含有具有促进健康作用以及抗氧化和甜味特性的生物活性化合物。然而，它们的顺序提取尚未实现。在本研究中，首先通过一种环保方法——超声辅助水提取（UAWE）从废弃橄榄渣（EOP）中提取抗氧化剂和甘露醇。根据Box-Behnken实验设计评估了振幅（20 - 80%）、提取时间（2 - 18分钟）和固含量（2 - 15%，/）。使用响应面法获得了最佳提取条件：80%振幅、11.5%固含量和16分钟。这实现了总酚含量（TPC）（40.04毫克/克EOP）、羟基酪醇含量（6.42毫克/克EOP）、甘露醇含量（50.92毫克/克EOP）和抗氧化活性（铁还原能力或FRAP，50.95毫克/克EOP；ABTS，100.64毫克/克EOP）的多响应优化。此外，通过液相色谱 - UV和质谱法测定提取物的酚类谱，确定羟基酪醇为主要酚类化合物，并对其他次要衍生物进行了表征。使用扫描电子显微镜分析UAWE后EOP细胞结构产生的形态变化。此外，对提取的EOP固体的化学成分进行了表征，以便进一步增值利用。然后，进行第二步提取，以便从后一种固体中提取生物活性三萜。测定了提取物中的三萜含量，并评估了先前UAWE步骤对三萜提取的影响。在这种情况下，超声的使用增强了从造粒EOP中提取山楂酸和齐墩果酸的能力，且无需研磨。总体而言，UAWE可作为第一步从造粒EOP中提取抗氧化化合物和甘露醇，同时支持后续三萜酸的回收。
