RESUMO
Since olive leaf is a potential source of phenolic fraction that is assumed to have good antioxidative effects, we purposed to add its extract to the refined olive-pomace oil during heating to increase its oxidative stability. RP-UHPLC-DAD-QTOF-MS was employed to characterize the phenolic fraction.The oil samples were evaluated by measuring the polymers and the polar compounds and thus detecting specific oxidized compounds. Using this approach, the results showed that incorporating olive leaf extract in refined oil significantly reduced the formation of polymers from 14.39% to 10.45% and the oxidation state by the variation of extinction ΔK from 3.02 to 2.29 during 20 h of heating compared to unenriched oil. This study has proven that the use of natural substances is an opportunity to extend the life of refined oils.
Assuntos
Aditivos Alimentares/análise , Glucosídeos/química , Iridoides/química , Olea/química , Azeite de Oliva/química , Extratos Vegetais/análise , Folhas de Planta/química , Piranos/química , Cromatografia Líquida de Alta Pressão/métodos , Manipulação de Alimentos , Temperatura Alta , Glucosídeos Iridoides , Espectrometria de Massas/métodos , OxirreduçãoRESUMO
Hexane, ethyl acetate and methanol extracts of Onopordum espinae leaves were investigated for their antibacterial activities against Bacillus cereus, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Salmonella enteritidis. Hexane and ethyl acetate extracts were toxic to Gram-positive bacteria with inhibition zone diameters ranging between 12 and 30 mm. Two products, hispidulin 1, and dehydromelitensin-8-(4ê-hydroxy-methacrylate) 2 were isolated from the ethyl acetate extract of leaves and identified by 2D-NMR for the first time from this species. Ethyl acetate extractês total flavonoid content was the highest, as 78.73 mg quercetin equivalents (QE)/g. The methanol extract showed the highest total phenolic content as 243.43 mg gallic acid equivalents (GAE)/g and gave the most important 2,2-diphenyl-1-picrylhydrazyl (DPPH)scavenging activity (EC50 = 86 µg/mL).
