Antioxidant effect of polyphenols extracted from pomegranate peel on vegetable oil/ethylcellulose-based oleogels
The objectives of the present work were to evaluate the use of polyphenols extracted from pomegranate peel as an antioxidant agent for the development of ethylcellulose based oleogels on vegetable oil and stablish the optimal amount of polyphenols necessary to preserve the oleogel oxidative stability and its mechanical properties. Pomegranate peel polyphenols (pp-polyphenols) were extracted and purificated, dehydrated and pulverized; their components were characterized by HPLC-MS/MS and the polyphenols was purified by HPLC-flash. Using Taguchi's methodology (orthogonal array L9 33), the factors ethylcellulose 45 cP (3, 6 and 12%), pp-polyphenols (0.05, 0.1 and 0.2%) and temperature (140, 150 and 160 °C) were evaluated on the oxidation of lipids produced during the oleogel elaboration process through peroxide and conjugated dienes methods and complemented with FTIR. Mechanical properties of the oleogels developed also were determined. Based on Taguchi's statistical model, the formulation with 3% EC and 0.1% pp-polyphenols and the thermal procedure at 160 °C for 2 hours was selected, under these conditions the greatest oxidation inhibition was obtained (up to 90%). The peroxides value determined in this sample (5.62 ± 0.4 mEq/kg) was within the limit allowed for edible vegetable oils (maximum 10 mEq/kg). It was determined that neither the addition of polyphenols nor the established thermal process altered the mechanical properties of the oleogels, regardless of the addition of pp-polyphenols. It was suggested to complement this work with the investigation of the synergism between pp-polyphenols and the components of the oleogel before suggesting a functionality or possible application.
Keywords: oleogel; ethylcellulose; punicalagin; polyphenols.
;)
