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. 2025 Apr 12;14(8):1336.
doi: 10.3390/foods14081336.

Increasing the Bioactive Compound Content of Olive Oil by Acidification of Olive Paste

Raúl Peralta  1 , Alfonso M Vidal  1   2 , Francisco Espínola  1   2 , María Teresa Ocaña  3 , Manuel Moya  1   2
Affiliations

Increasing the Bioactive Compound Content of Olive Oil by Acidification of Olive Paste

Raúl Peralta et al. Foods. .

Abstract

This study investigated the impact of acidification on olive paste to enhance the extraction of olive oil enriched in bioactive phenolic compounds, aiming to develop a novel functional food. Recognizing that acidic pH promotes the activity of β-glucosidase responsible for oleuropein and ligstroside hydrolysis, food-grade organic acids-citric, ascorbic, and acetic acid-were added prior to malaxation to improve the bioactive compound content in the resulting oils. A randomized experimental design was employed, using three different doses of each acid (1, 2, and 4%) with three replicates per dose, alongside control trials without acid addition. Acidification did not affect olive oil extraction efficiency or alter quality parameters for extra virgin olive oils. Treatment with 1% ascorbic acid significantly increased phenolic compound content by 37% compared to controls. Secoiridoids comprised 79.4% of the total phenolic content, with oleacein as the predominant compound (237.58 ± 9.18 mg/kg), representing over 50% of the total. This increased oleacein concentration led to up to a 67% enhancement in antioxidant capacity (428.63 ± 31.57 mg Trolox/kg) compared to controls. The antioxidant capacities of 3,4-DHPEA, 3,4-DHPEA-EDA, and 3,4-DHPEA-EA were determined to be 12.05, 5.80, and 4.91 µmol TE/mg, respectively. Furthermore, the 1% ascorbic acid treatment enhanced volatile compounds associated with the lipoxygenase (LOX) pathway while reducing ethanol levels.

Keywords: antioxidant capacity; hydroxytyrosol; oleacein; oleocanthal; phenolic compounds; secoiridoid.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Secoiridoid formation from oleuropein/ligstroside hydrolysis and the subsequent conversion to hydroxytyrosol/tyrosol.
Figure 2
Figure 2
Relationship between antioxidant capacity and the content of oleuropein derivatives (hydroxytyrosol + oleacein + oleuropein aglycone), secoiridoids, and total phenols in the oils.
Figure 3
Figure 3
Relationship between antioxidant capacity and the content of oleuropein derivatives (hydroxytyrosol + oleacein + oleuropein aglycone).
See this image and copyright information in PMC

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