Integrated Process for Sequential Extraction of Bioactive Phenolic Compounds and Proteins from Mill and Field Olive Leaves and Effects on the Lignocellulosic Profile

María Del Mar Contreras; Antonio Lama-Muñoz; José Manuel Gutiérrez-Pérez; Francisco Espínola; Manuel Moya; Inmaculada Romero; Eulogio Castro

doi:10.3390/foods8110531

Integrated Process for Sequential Extraction of Bioactive Phenolic Compounds and Proteins from Mill and Field Olive Leaves and Effects on the Lignocellulosic Profile

Foods. 2019 Oct 29;8(11):531. doi: 10.3390/foods8110531.

Authors

María Del Mar Contreras¹, Antonio Lama-Muñoz², José Manuel Gutiérrez-Pérez^{3

4}, Francisco Espínola^{5

6}, Manuel Moya^{7

8}, Inmaculada Romero^{9

10}, Eulogio Castro^{11

12}

Affiliations

¹ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. mcgamez@ujaen.es.
² Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. alama@ujaen.es.
³ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. jmgp0014@red.ujaen.es.
⁴ Center for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. jmgp0014@red.ujaen.es.
⁵ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. fespino@ujaen.es.
⁶ Center for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. fespino@ujaen.es.
⁷ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. mmoya@ujaen.es.
⁸ Center for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. mmoya@ujaen.es.
⁹ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. iromero@ujaen.es.
¹⁰ Center for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. iromero@ujaen.es.
¹¹ Department of Chemical, Environmental and Materials Engineering, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. ecastro@ujaen.es.
¹² Center for Advanced Studies in Energy and Environment, University of Jaén, Campus Las Lagunillas, 23071 Jaén, Spain. ecastro@ujaen.es.

Abstract

The extraction of bioactive compounds in a biorefinery context could be a way to valorize agri-food byproducts, but there is a remaining part that also requires attention. Therefore, in this work the integrated extraction of phenolic compounds, including the bioactive oleuropein, and proteins from olive mill leaves was addressed following three schemes, including the use of ultrasound. This affected the total phenolic content (4475.5-6166.9 mg gallic acid equivalents/100 g), oleuropein content (675.3-1790.0 mg/100 g), and antioxidant activity (18,234.3-25,459.0 µmol trolox equivalents/100 g). No effect was observed on either the protein recovery or the content of sugars and lignin in the extraction residues. Concerning the recovery of proteins, three operational parameters were evaluated by response surface methodology. The optimum (63.1%) was achieved using NaOH 0.7 M at 100 °C for 240 min. Then, the selected scheme was applied to olive leaves from the field, observing differences in the content of some of the studied components. It also changed the lignocellulosic profile of the extraction residues of both leaf types, which were enriched in cellulose. Overall, these results could be useful to diversify the valorization chain in the olive sector.

Keywords: bioactive compounds; biorefinery; oleuropein; olive leaves; phenolic compounds; ultrasound; vegetable protein.

Grants and funding

Acción 6 del Plan de Apoyo a la Investigación de la Universidad de Jaén, 2017-2019/Universidad de Jaén