Entry #: 38
Date: 27 February 2018
Section: Phenolic extracts
Topic: Phenolic extracts and anti-microbial effects
Type: Original paper

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OliveNetTM Journal Club

Expert review of literature related to olives and olive oil

D. Elizabeth McCord, Nancy B. Ray and Tom C. Karagiannis

Title

Enrichment of phenolic compounds from olive mill wastewater and in vitro evaluation of their antimicrobial activities

Author(s)

Abu-Lafi et al

Citation / Year

(1) / 2017

Keywords

Phenolic extracts, olive mill wastewater, hydroxytyrosol, tyrosol, antibacterial, antifungal

Summary

Production of olive oil results in the accumulation of huge amounts of olive mill wastewater. This wastewater contains phytotoxins representing an important environmental issue, and presents difficulties associated with storage or disposal (2, 3). Given the high levels of phenolic compounds in olive mill wastewater, there is considerable interest in utilising this material as a starting point for enriching or even isolating pure bioactive compounds (4, 5). For example, phenolics compounds could have important applications in the food industry, supplements, cosmetics, pharmaceutical industries (5, 6). Therefore, cost-effective methodologies for enriching or isolating bioactive compounds from olive mill wastewater is an important research direction. As a proof-of-principle, in this work, ethyl acetate was utilised as solvent for preparing polyphenolic extracts from 20 litres of wastewater collected from an olive mill.

Key points and implications

The ethyl acetate extraction process resulted in polyphenolic extracts with an approximately 1% (wt/wt) yield. The extracts were shown to contain the key bioactive olive phenolics, hydroxytyrosol and tyrosol; oleuropein was not detected in the extracts. Similarly, a significant flavonoid content was detected. The antioxidant activity of the extracts was monitored using the ferric and cupric reducing antioxidant assays and well-established in vitro assays were utilised to determine free radical scavenging activity. Importantly, bioactive properties of the extract was highlighted using these antioxidant and free radical scavenging assays. The findings also indicated the extracts possessed and antibacterial activity against Staphylococcus aureus (gram positive), and Escherichia coli (gram negative). Similarly, the extract was effective against Candida albicans and Aspergillus niger highlighting antifungal properties. Given these properties, extracts were introduced into olive oil (at 0.5 and 1%), to improve the antioxidant content and preservation of the olive oil, is indicated by enhanced stability, oil acidity, and peroxide value. Overall, this work represents a key research direction with respect to an important environmental issue arising from the production of olive oil. The possibility of cost-effective enrichment of bioactive compounds from essentially a waste product is anticipated intensely pursued in future research efforts.

Related publications

  1. S. Abu-Lafi, M. S. Al-Natsheh, R. Yaghmoor, F. Al-Rimawi, Enrichment of Phenolic Compounds from Olive Mill Wastewater and In Vitro Evaluation of Their Antimicrobial Activities. Evidence-based complementary and alternative medicine : eCAM 2017, 3706915 (2017).
  2. N. Kalogerakis, M. Politi, S. Foteinis, E. Chatzisymeon, D. Mantzavinos, Recovery of antioxidants from olive mill wastewaters: a viable solution that promotes their overall sustainable management. Journal of environmental management 128, 749-758 (2013).
  3. C. I. Justino et al., Olive oil mill wastewaters before and after treatment: a critical review from the ecotoxicological point of view. Ecotoxicology 21, 615-629 (2012).
  4. N. Caporaso, D. Formisano, A. Genovese, Use of phenolic compounds from olive mill wastewater as valuable ingredients for functional foods. Critical reviews in food science and nutrition, 1-13 (2017).
  5. E. Frankel, A. Bakhouche, J. Lozano-Sanchez, A. Segura-Carretero, A. Fernandez-Gutierrez, Literature review on production process to obtain extra virgin olive oil enriched in bioactive compounds. Potential use of byproducts as alternative sources of polyphenols. Journal of agricultural and food chemistry 61, 5179-5188 (2013).
  6. R. Delisi, F. Saiano, M. Pagliaro, R. Ciriminna, Quick assessment of the economic value of olive mill waste water. Chemistry Central journal 10, 63 (2016).