Two Varieties of Onion Peel Extracts to Monitor Oxidation in Beef Model System

This study investigated the effects of yellow onion peel extract powder (YOEP) and red onion peel extract powder (ROEP) in beef batters on oxidative stability during storage at 4°C for 7 days. The total phenolic content of ROEP and YOEP was 28.91 and 18.56 mg GA/g peel, respectively, while their DPPH radical scavenging activities were 92.38% and 95.60%, respectively. The initial pH values (̴5.7) increased significantly during storage in all groups (p < .001), but this increase was less pronounced in the ROEP-treated samples, which exhibited a pH of 6.39 on day 7, compared with 6.63 and 6.59 in the CONT and YOEP groups, respectively. The natural purplish pigments of ROEP affected meat colour, resulting in lower a* values (p < .05). Metmyoglobin formation reached its maximum values of 81.95%, 80.43%, and 72.04% in the CONT, YOEP, and ROEP, respectively, on day 4 (p < .001). Both extracts effectively delayed lipid oxidation during storage. ROEP showed the strongest protective effect, exhibiting the smallest increase in thiobarbituric acid reactive substance (TBARS) values after 7 days (0.57 mg MA/kg) compared with the initial levels (0.44 mg MA/kg), indicating its superior potential as a natural antioxidant for improving oxidative stability in meat systems.