Research On Antioxidant Ability Of Licorice Extracts And The Application In Rabbit Meat

Research on Antioxidant Ability of Licorice Extracts and the Application in Rabbit Meat Licorice extracts are safe and efficient natural antioxidants,which is used as meat preservatives to prevent meat from deterioration and fat oxidation.Rabbit meat proximate composition demonstrates its protein rich and high levels of unsaturated fatty acids,serving as a mentality improving and hairdressing food.However,unsaturated fatty acids and protein are easily oxidized in processing and storage,generating off-flavor,and also leading to nutritional quality and sensory quality(color?texture)decline.In this study,extracts of licorice Glycyrrhiza uralensis as antioxidants and hindlegs meat of Sichuan white rabbit are mainly used as materials.In vitro antioxidant capacity and stability of three different licorice extracts,including aqueous extract and ethanol extracts of licorice roots and a purchased extract,were tested in this paper,and glycyrrhizic acid conent and the content of total phenols and flavonoids of extracts were also analyzed.The extracts were added to grounded abbit meat to evaluate the antioxidant activity in fat and protein oxidation during cooking and baking process,as well as cold storage.Main conclusions were as follows:(1)Aqueous and ethanol extracts of roots of licorice and a bought licorice extract were compared in total antioxidant capacity and antioxidant components.The results showed that aqueous extract had the highest glycyrrhizic acid conent and the content of total phenol and flavonoids,and the other two extracts also contained some quantities of those.In addition,aqueous extract was the most active in scavenging ABTS and hydroxyl free radicals and also Fe3+ reduction reaction,while the purchased extract was the most active of the three in scavenging DPPH free radicals.All licorice extracts were quite stable during cold storage at 4?.(2)The antioxidant eff ects of the three licorice extracts on grounded rabbit meat was determined during the cooking process by TBARS(thiobarbituric acid reactive substances),comparing with synthetic antioxidant(BHT,butylated hydroxytoluene).Results showed that all three licorice extracts were effective in protecting lipids from oxidation during cooking process.Aqueous and ethanol extracts were especially active during cooking at 80?90 and 100?,while the purchased licorice extract was active during cooking at various temperature(70,80,90 and 100?).(3)The antioxidant eff ect of the three licorice extracts on grounded rabbit meat protein was determined during the cooking process,in comparison with synthetic antioxidant(BHT).Results showed that the aqueous licorice extract and purchased licorice extract were strongly effective in inhibiting protein oxidation during cooking,and the effectiveness increased with increasing temperature.The ethanol extract also showed antioxidant activity in protein oxidation to some degree,especially during cooking at 90? and 100?.(4)The antioxidant eff ect of the three licorice extracts on lipids of grounded rabbit meat was determined during the high-temperature baking process by TBARS,comparing with synthetic antioxidant(BHT).Results showed that all three licorice extracts also showed high antioxidant activity in lipids oxidation during high-temperature baking.During 120 and 180? baking,aqueous and ethanol extracts exhibited effective antioxidant activity on lipids.However,the antioxidant activity was very low at 250?.The purchased licorice extract was very active at all temperature(120?,180? and 250?),and the efficacy increasing with increasing temperature.(5)The antioxidant eff ect of the three licorice extracts on grounded rabbit meat protein was determined during the high-temperature baking process,comparing with synthetic antioxidant(BHT).Results showed that the aqueous licorice extract revealed highest antioxidant activity in protein oxidation during baking,which is as effective as 0.2g/kg BHT at various tempreture(120,180 and 250?).The purchased licorice extract showed a stronger activity than 0.05g/kg BHT,while the ethanol extract showed little antioxidant activity during baking at 180 and 250?.(6)The antioxidant activity of meat treated with three different licorice extracts,during storage at 4?for 10 days,was determined using the following assays: fatty acids composition determination and a thiobarbituric acid(TBA)assay.The results showed that in the ethanol and the purchased licorice extracts treatments,the oxidation of lipids were significantly reduced,while the aqueous licorice extract treatment exhibited little antioxidant activity in lipids oxidation.Three licorice extracts all revealed high antioxidant activity in polyunsaturated fatty acids,especially n-3 polyunsaturated fatty acids.However,all licorice extracts were incapable of keeping n-3/n-6 ratio under 10 after 10 days' cold storage.(7)The antioxidant activity of meat treated with three different licorice extracts,during meat storage at 4? for 10 days,was determined using the following assays: thiol content and redness assay.Only the aqueous licorice extract exhibited antioxidant activity in myoglobin oxidation,while the antioxidant activity of ethanol licorice extract was not detected in myoglobin oxidation.Three licorice extracts were highly active in thiol oxidation,and among them,both aqueous and ethanol licorice extracts were as active as 0.2g/kg BHT.