## 1 Introduction
However, high-temperature heating causes uncontrolled oxidation of highly unsaturated oils, triggering a series of complex chemical reactions that lead to the formation of various oxidation products, such as acids, aldehydes and ketones, and ultimately, to lipid peroxidation [27; 28; 29]. Oxidation of vegetable oil results in a significant decrease in the nutritionally mostly beneficial polyunsaturated fatty acids, while the contents of trans isomers and saturated fatty acids exhibiting unfavourable nutritional effects are significantly increased [30; 31]; this eventually causes adverse physiological reactions [32] and reduces the palatability of the ration, which affects animal feeding and can lead to refusal to eat, post-feeding poisoning or even death [33; 34]. Thus, in order to retard or inhibit oxidative processes and increase the health aspects and nutritional value of oil, some synthetic antioxidants, such as butylated hydroxyapatite (BHA), hydroxytoluene (BHT), propyl gallate (PG), tert-butylhydroquinone (TBHQ) and ethoxyquin (EQ), have been used to delay the oxidative deterioration of oil during storage [35; 36], but synthetic antioxidants have come under scrutiny due to potential toxicological effects and human health risks. Therefore, the use of synthetic antioxidants has been restricted [37]. Natural products are again the focus of attention, including useful and natural plant-based antioxidants, such as tea extracts [38], rosemary extracts [39] and curcumin [40], which are used for food protection and disease prevention. Therefore, research on safe and effective natural antioxidants from natural sources, such as phenolic compounds, is being explored to find antioxidants capable of protecting fats and oils from oxidation [41]. QG is a bioactive component found in the forage plant margold, where it exhibits high content and strong antioxidant capacity. Its antioxidant capacity can be exploited in the feed industry to maintain feed quality by using marigold as a source of antioxidants that prevent rancidity and the oxidation of lipids. However, no studies have been conducted to determine the efficacy of QG in preventing lipid oxidation under accelerated oxidation conditions. Therefore, we investigated the effectiveness of different QG concentrations (100, 200, 400, 800 and 1600 ppm) in protecting soybean oil from accelerated oxidation and compared the antioxidant strength with those of the synthetic antioxidants BHT and PG and the natural antioxidant TP under the same conditions. The aim of the present study was to explore the effects of the strongest radical scavenging antioxidants found in marigold on the oxidative stability of soybean oil during accelerated oxidation. This study used an offline DPPH-HPLC-Q-TOF/MS system to identify potentially optimal antioxidants and to evaluate their effectiveness in retarding lipid oxidation in soybean oil by measuring the acid value, peroxide value, fatty acid composition and volatiles composition during accelerated oxidation storage. The results of this study indicated that QG is the best antioxidant among four antioxidant components identified in marigolds, and it significantly improved lipid stability during the accelerated oxidation of soybean oil. Therefore, the study suggested that QG has great potential for use as a natural antioxidant in feed additive products.