Effectiveness of red propolis extract as a natural antioxidant in frozen lamb burgers

The antioxidant effects of red propolis extract were evaluated in lamb burgers stored for 120 days at -18 °C. The treatments prepared were CON (control, no antioxidant), ERI (500 mg/kg sodium erythorbate), P1800 (1800 mg/kg propolis extract), and P3600 (3600 mg/kg propolis extract).The analyses performed were proximate composition (moisture, protein, fat, and ash), texture, and sensory acceptance (day 0); pH, color profile (L*, a*, b*), weight loss of cooking (WLC), diameter reduction, TBARS, and peroxide index (0, 30, 60, 90, and 120 days); and fatty acid profile and volatile compounds (0 and 120 days). No treatment was associated with a change in the proximate composition. Most texture parameters in treatments P1800 and P3600 were lower (P < 0.05), and it can be concluded that the extract favors the improvement of this sensory attribute, making the hamburgers softer. The WLC was higher in the treatments where the extract was used; however, the reduction of the diameter of the hamburgers was lower, an important aspect for consumers. The extract retarded lipid oxidation during storage, especially P3600, which presented the lowest level of TBARS (1.37 mg MDA/kg) and the peroxide index (5.69 mEq g of O₂) on day 120. The presence of volatile compounds derived from lipid oxidation was more evident in the CON and ERI treatments, showing the efficiency of natural antioxidants used in the P1800 and P3600 treatments. It is concluded that red propolis represents an excellent alternative for replacement of synthetic antioxidants with natural products in lamb hamburgers.