Antioxidant properties from Tagete filifolia essential oil with high estragole + anethole content by analysis of thermal stability and oxidation: chemical, volatile and sensory determinations

Abstract

Tagete filifolia essential oil (TEO) with a high content of estragole and anethole is thermally stable and protects lipids from oxidation, which allows it to be potentially used as an antioxidant. The objective of this research is to assess the TEO with high content (+95%) of estragole and anethole (22.8% and 77.0% respectively) as a possible crop for industrial application, considering its potential antioxidant activity. The thermal stability of TEO (60°C - 28 days) was determined by analysing its volatile chemical composition (SPME-GC-MS). Indirect antioxidant activity of TEO was performed with Free Radical Scavenging Activity (FRSA-DPPH) and Total Phenol Content (TPC). Direct measurement used an accelerated oxidation test at 60°C for 14 days in concentrations of 0.02, 0.10 and 0.20 %w/w of EO in sunflower vegetable oil (chemical, volatile and sensory oxidation compounds were analysed). The results showed that anethole and estragole are thermally resistant, and together amount to 99.8% after 28 days. Estragole decreased from 24.3% to 21.3%, while anethole increased from 75.1% to 78.5% between day 0 and day 28 of the trial. Indirect measurement revealed low FRSA (11.1% of DPPH inhibition) and TPC (2.1 mg/g) activity. In the direct determination, protection against the control was observed (TOTOX Value Control > TEO > BHT0.02%; 186, ≈ 150 and 134, respectively); However, the antioxidant activity did not show a direct correlation between the dose level used and the expected response. The results indicated that the essential oil could be applied as an antioxidant in a variety of products.