Improved oxidative stability and sensory quality of beef hamburgers enriched with a phenolic extract from olive vegetation water

This study aims at evaluating the effect of a phenol-rich extract obtained from the concentration and purification of olive mill wastewaters (added at a ratio of 87.5 and 175 mg of phenols/kg meat) on the stability and sensory quality of beef hamburgers packed under modified atmosphere and stored under alternating exposure to fluores-cent light at 4±2°C for 9 days. Hamburgers were sampled at different times (0, 6 and 9 days) and grilled at 200°C. After 9 days, more than 56% of the added phenols in the raw burgers and more than 20% the grilled ones, were retained. The results show that both concentrations of phenolic extract proved to effectively reduce primary and sec-ondary lipid oxidation, as well as cholesterol oxidation products (COPs), during the shelf-life of raw hamburgers. Peroxide value, thiobarbituric acid reactive substances and total COPs were up to 1.4-, 4.5- and 8.8-fold lower in phenol-enriched raw ham-burgers, respectively, than in control samples; a similar trend was noted also in phe-nol-enriched cooked hamburgers (1.3-, 5.7- and 4-fold lower). Sensory analysis also confirmed the effectiveness of the addition of phenolic extract, having a positive effect on the red color intensity (raw product) and thus reducing browning during storage