Relations between Oxidative Stability and Antioxidant Content in Vegetable Oils Using an Accelerated Oxidation Test - Rancimat

摘要

In vegetable oils, particularly virgin olive oil and sunflower oil and in lard, the effects of temperature and antioxidant extracts concentration on the induction time were investigated using a sequence of simple factorial designs.nnThe antioxidant extracts were obtained from aromatic plants by hydrodistillation followed by liquid-liquid extraction using diisopropyl ether as a solvent. Vegetable oils and lard were spiked with those extracts in a range of concentrations from 250 to 2500 ppm and then subjected to oxidation in a 679 Rancimat apparatus.nnIn the sequence of factorial designs, two blocks of 23 design were run. In the first block only peppermint extract was used in two different matrices (virgin olive oil and sunflower oil). In the second block the antioxidant extract was introduced as a new variable but keeping the same matrix (sunflower oil). A simple equation was derived trying to relate the induction time (TI) with the extract concentration (C). The model was validated with data obtained from rosemary (Rosmarinus officinalis), peppermint (Mentha piperita), lemon balm (Melissa officinalis) and marjoram (Origanum majorana) in virgin olive oil and sunflower oil at temperatures of 100, 110, 120, 130, 140 and 150 °C. To confirm the results, supplementary experiments were done with peppermint in lard at 120 and 130 °C.