Main content area

Phenolic extracts obtained from thermally treated secondary varieties of dates: Antimicrobial and antioxidant properties

Mrabet, Abdessalem, García-Borrego, Aranzazu, Jiménez-Araujo, Ana, Fernández-Bolaños, Juan, Sindic, Marianne, Rodríguez-Gutiérrez, Guillermo
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2017 v.79 pp. 416-422
2,2-diphenyl-1-picrylhydrazyl, antioxidant activity, bioactive compounds, cultivars, food industry, heat treatment, hydroxymethylfurfural, lipid peroxidation, liquids, median effective concentration, plant pathogens, risk, solvents, steam, sugars, sunflower oil, temperature
Palm dates are an important source of natural bioactive compounds and their application in the food industry could valorize secondary cultivars at risk of disappearing. Secondary palm date varieties were thermally treated by direct steam at two temperatures (140 and 160 °C) during 30 min. The liquid was extracted by organic solvent, obtaining two extracts, PE140 and PE160, with high concentrations of sugar degradation products, mainly hydroxymethylfurfural and phenolic compounds like tyrosol or gallic and protocatechuic acids. The use of the higher temperature produced 22 g of extract/Kg of fresh dates with antioxidant activities in the aqueous matrix (EC50 value of 2.72 mg/L for DPPH and TEAC value of 0.05 mmol Trolox®/g of extract) and remarkable protection against lipid oxidation in oils, increasing the stability of sunflower oil by the Rancimat method by four-fold. Promising values of inhibition against plant pathogens were found with values of MIC of 3.13 mg/mL. Therefore, thermal treatment of dates was effective for obtaining bioactive phenolic extracts suitable for food formulation.