PROPOLIS EXTRACT AS A NATURAL ANTIOXIDANT IN SHEEP MEAT BURGERS

Sheep meat and its derivatives are susceptible to lipid oxidation due to their unsaturated fatty acid profile, making green propolis extract a potential natural preservative. This study evaluated the effects of green propolis extract inclusion levels (0 to 1.5 g/kg) on the physicochemical and technological characteristics of sheep meat burgers during refrigerated storage. The extract was obtained using 80% ethanol in a water bath (50 °C/30 min), centrifuged, and concentrated via a rotary evaporator. It was characterized for total phenolic content and antioxidant activity (DPPH). Four treatments were produced in three batches: Control (CON) and green propolis extract inclusion at 0.5 (T1), 1.0 (T2), and 1.5 g/kg (T3) of meat, stored for 21 days at 4 °C. Proximate composition was determined on day 0. On days 0, 7, 14, and 21, pH, color, TBARS, texture profile analysis (TPA), diameter reduction, water-holding capacity (WHC), and cooking loss were evaluated. Data were subjected to a linear mixed-effects model in R software, applying Tukey’s test (p<0.05) for mean comparisons.The extract exhibited high total phenolic content (3720.24 mg GAE/100 g) and significant DPPH antioxidant activity (3146.18 mg Trolox/g). Proximate composition did not differ among treatments (p>0.05). The TBARS index was significantly higher in CON compared to T3 on day 0 (1.29 vs. 1.05 mg MDA/kg; p<0.0001) and day 21 (0.96 vs. 0.63 mg MDA/kg), demonstrating that increasing extract concentration reduced lipid oxidation. The pH decreased after day 0 and stabilized throughout storage. The CON group showed lower initial WHC (60.5%; p<0.0001); however, on days 14 and 21, extract treatments exhibited significantly higher and dose-dependent WHC values. Purge loss decreased significantly at higher extract doses from day 7 to 21. Regarding color, T2 and T3 exhibited higher yellowness only on day 0 due to exogenous pigments.Both raw and cooked, CON exhibited significantly greater hardness than extract treatments from day 0 to 21 (raw: 6.76 N for CON vs. 3.69 N and 3.38 N for T2 and T3; cooked on day 21: 62.90 N for CON vs. 43.30 N for T3). The CON group also exhibited significantly higher initial cohesiveness (0.543 vs. 0.381 for T2) and springiness (4.84 and 4.88 mm vs. 3.81 mm for T3). However, both variables increased similarly with increasing extract concentration until the end of storage (p<0.01). In conclusion, green propolis extract (1.5 g/kg of meat) is an efficient natural preservative that delays lipid oxidation and preserves WHC, resulting in softer, more elastic, and structurally integrated burgers after 21 days. Financial support: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001