A Comparative Study On The Antioxidant Activities Of Some Natural Antioxidants

Natural antioxidants become more and more popular since they have the advantages of avirulence and non-side-effects. Besides it can prevent oxidation of oil and fats as food additi- ve , by scavenging the free radicals in body natural antioxidants can prevent consenescence and disease .Up to now, people have carried out deep studies on the antioxidation activities of many kinds of natural antioxidants , respectively , and have made great achievements , while comprehensive comparative studies on several natural antioxidants have seldom been reported. Several representative natural antioxidants such as Vc,VE,TP,rosemary extract,β-carotene and lycopene with synthetic antioxidant TBHQ as control were comparatively studied on their antioxidant activities and synergistic effect in different systems.Firstly,the antioxidant activities of the antioxidants in the refining rapeseed oil, soybean oil and lard were comparatively studied by the oven method, and the results showed that in the rapeseed and soybean oil antioxidant abilities were in the same order: TBHQ> TP> rosemary extract> lycopene> VC≈β-carotene≈VE. While in the lard, TBHQ,TP,rosemary extracts and Vc had good antioxidant activities. The results of comparative study on antioxid- ant factors showed that: it could significantly reduce the antioxidant activities of TBHQ,TP and rosemary extracts in soybean oil at the high temperature 80℃;The 0.2 % water could only enhance theβ-carotene's antioxidant activity in soybean oil and had few effects on the other antioxidants; For TBHQ,TP,rosemary extracts and lycopene, 2 mg/kg Fe3+could significantly reduce their antioxidant activities in the soybean oil. However, 0.2 mg/kg Cu2 + had a negative effects on the lycopene's antioxidant activity in the soybean oil .Secondly, the radical scavenging activities were studied with different assayes , the results of DPPH radical scavenging activities was TP >TBHQ> Vc >rosemary extracts> VE >lycopene>β-carotene. PMS-NADH system can generate superoxide radical which can deoxidize NBT. The results showed that this method was suitable to evaluate the superoxide radical scavenging activities of TP and rosemary extracts, and the activity of TP was much greater than rosemary extracts. But this method could not be used to evaluate the superoxide radical scavenging activities of TBHQ , VC, VE, lycopene andβ-carotene. 1,10-Phenanthroline -Fe2+ oxidative assay could not evaluate the hydroxyl radical scavenging activities of TP , rosemary extracts,β-carotene and lycopene.Finally, the synergistic antioxidation experiments in the rapeseed oil showed that: there were positive synergies between Vc and VE,TP,rosemary extract,β-carotene,lycopene, VE andβ-carotene,lycopene, TP and rosemary extracts ,the the synergy between VE and Vc was the strongest,and between other combinations were negative synergies. The antioxidant activities of Vc and rosemary extracts, TP and rosemary extracts, TP and Vc were better.When total addition was 0.02%, PV of oil with 0.015 %TP and 0.005%rosemary added was12.98 meq/kg ,the antioxidant activity of it was the best.