The effect of natural antioxidants extracted from plant and animal resources on the oxidative stability of soybean oil

• The antioxidant activity of animal protein hydrolyzates isolate and olive leaf extracts was compared with BHT.
• Cow's intestine protein hydrolysates isolate at 1000 mg/kg showed best oxidative protection activity.
• The release and destruction of natural antioxidants were controlled by encapsulation.

The objective of this study was to evaluate and compare the antioxidant activity of protein hydrolyzates isolate (PHI) from Crucian carp (Carassius carassius) fish and cow's intestine along with microwave-assisted olive leaf extract (OLE) encapsulated by Arabic gum and maltodextrin, in soybean oil. The antioxidant activity of PHIs at three concentrations of 200, 500 and 1000 mg/kg and OLE samples containing 70 mg/kg total phenolics during 20 days storage was evaluated by peroxide value, TBA value, p-anisidine value and Rancimat stability test. The fish PHI at concentration of 1000 mg/kg, cow's intestine PHI at 500 and 1000 mg/kg and OLE encapsulated with Arabic gum showed best oxidative protection activity (more than BHT at 100 and 200 mg/kg). OLE had a suitable antioxidant activity in soybean oil and encapsulation improved the thermal stability of phenolic compounds, but on the other hand, it decreased the antioxidant efficiency of OLE.