Effect of Ohmic Heating on the Extraction Yield, Polyphenol Content and Antioxidant Activity of Olive Mill Leaves

Fereshteh Safarzadeh Markhali, José A. Teixeira and Cristina M. R. Rocha
Additional contact information
Fereshteh Safarzadeh Markhali: CEB–Centre of Biological Engineering, Campus of Gualtar, University of Minho, 4710-057 Braga, Portugal
José A. Teixeira: CEB–Centre of Biological Engineering, Campus of Gualtar, University of Minho, 4710-057 Braga, Portugal
Cristina M. R. Rocha: CEB–Centre of Biological Engineering, Campus of Gualtar, University of Minho, 4710-057 Braga, Portugal

Clean Technol., 2022, vol. 4, issue 2, 1-17

Abstract: This study examined the influence of ohmic heating ( OH ), compared to the conventional heating ( Conven ) and Control (solvent) methods, on the extraction of olive mill leaves. The main extraction parameters were: (i) solvent ratio (aqueous ethanol; 40%, 60%, and 80%, v / v ), and (ii) extraction temperature; 45 °C, 55 °C, and 75 °C (for OH and Conven ), and room temperature (for Control ). The selected response variables were extraction yield (%), total phenolic content (TPC), and antioxidant activity (ABTS and DPPH). The ohmic system, compared to Conven and Control , exhibited the greatest effects ( p < 0.001) on increasing (i) extraction yield (34.53%) at 75 °C with 80% ethanol, (ii) TPC at 55 °C (42.53, 34.35, 31.63 mg GAE/g extract, with 60%, 40%, and 80% ethanol, respectively), and (iii) antioxidant potency at 75 °C detected by DPPH and ABTS, in the range of 1.21–1.04 mM TE/g, and 0.62–0.48 mM TE/g extract, respectively. Further, there were relatively similar trends in TPC and antioxidant activity (both methods), regardless of solvent ratios, p < 0.001. These findings demonstrate the potential of ohmic heating, as a green processing tool, for efficient extraction (15 min) of olive leaves. To date, no literature has described ohmic application for olive leave extraction.

Keywords: ohmic heating; olive leaves; residual biomass; polyphenols; antioxidant activity; green solvent; sustainable extraction (search for similar items in EconPapers)
JEL-codes: Q2 Q3 Q4 Q5 (search for similar items in EconPapers)
Date: 2022
References: View complete reference list from CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/2571-8797/4/2/31/pdf (application/pdf)
https://www.mdpi.com/2571-8797/4/2/31/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jcltec:v:4:y:2022:i:2:p:31-528:d:830026

Access Statistics for this article

Clean Technol. is currently edited by Ms. Shary Song

More articles in Clean Technol. from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().