The flavonoid content was measured using a colorimetric method, which is based on the formation of a complex between the aluminum ion and the carbonyl and hydroxyl groups of flavonoids that produce a yellow color. One milliliter (1 mL) of each extract, at different concentrations ranging from 0.125 to 1 mg/mL was mixed with 1 mL of a 2% aluminum chloride solution. Following incubation for 30 min, the absorbance of the reaction mixture was measured at 430 nm against distilled water blank. A standard curve of quercetin was drawn with a concentration range of 3.0 x 10–4 to 4.0 x 10–3 mg/mL, and the results wereexpressed as mg quercetin equivalents per 100g of dried extract (mg QE/100g of dried extract).
Author(s) Details:
Fatiha Abdellah
Laboratory of Research on Local Animal Products at Ibn Khaldoun University, Tiaret, Algeria.
Recent Global Research Developments in Antioxidant Activities of Olive Mill Wastewater
Olive mill wastewater (OMWW) is the main by-product of the olive oil extraction process. It contains valuable polyphenolic compounds known for their health-promoting benefits [1]. Here are some key findings from recent studies:
Polyphenolic Profile and Antioxidant Activity:
- Researchers characterized and compared the polyphenolic profile of OMWW generated by centrifugal three-phase olive oil mills processing two important Sicilian cultivars: Cerasuola and Nocellara etnea.
- Both OMWW samples showed high levels of antioxidant activity.
- Cerasuola-OMWW had higher values of total phenols, total flavonoids, and hydroxytyrosol content compared to Nocellara etnea-OMWW.
- These phytochemical values remained stable when stored at -20°C for 6 months but decreased when stored at 4°C or 25°C for 45 days [2].
Treatment for Polyphenol Enrichment:
- Another study treated OMWW using microfiltration (MF), nanofiltration (NF), and reverse osmosis (RO) to produce polyphenol-enriched fractions.
- These fractions were investigated for their chemical profile using ultra-high-performance liquid chromatography (UHPLC) and their potential antioxidant, hypolipidemic, and hypoglycemic activities [2].
References
- Di Mauro, M.D., Giardina, R.C., Fava, G. et al. Polyphenolic profile and antioxidant activity of olive mill wastewater from two Sicilian olive cultivars: Cerasuola and Nocellara etnea. Eur Food Res Technol 243, 1895–1903 (2017). https://doi.org/10.1007/s00217-017-2893-3
- Tundis R, Conidi C, Loizzo MR, Sicari V, Cassano A. Olive Mill Wastewater Polyphenol-Enriched Fractions by Integrated Membrane Process: A Promising Source of Antioxidant, Hypolipidemic and Hypoglycaemic Compounds. Antioxidants. 2020; 9(7):602. https://doi.org/10.3390/antiox9070602