Optimization Of Antioxidant Extraction Process And Application Characteristics From Rosemarys Leaves

Rosmarinus officinalis L.is an evergreen aromatic shrub of the genus Rosmarinus in the family Lamiaceae,which is a medicinal and dible plant bringing substantial economic benefit.The leaves are rich in acid phenols,alkene terpenes and flavonoids,which have antioxidant,anti-aging,antibacterial and other desirable effects.The complex components limits the functional evaluation and application of different active ingredients in rosemary extract,while enhancing the yield of active ingredients and reducing the technical cost are urgent problems for the antioxidant components of rosemary.In order to develop and utilize rosemary-resources for better,we used rosemary leaves as raw materials,optimized the extraction process of fat-soluble antioxidant components Carnosic acid(CA)and Carnosol by the method of ultrasound-assisted ethanol extraction.Meanwhile,determined their antioxidant capacity by multiple indicators.The ratio of natural antioxidant compound was optimized by orthogonal test of Rancimate.The antioxidant capacity of the optimal compound on rapeseed oil was studied.The shelf life of rapeseed oil was predicted.The main results are listed as follows:(1)A comprehensive comparison of the extraction rates among four solvents(acetone,ethyl acetate,methanol and ethanol)with different polarities for CA and camosol was performed.The results showed that ethanol was the optimal extraction solvent;The optimum technologic parameters for ultrasound-assisted ethanol extraction were determined by single-factor test as follows:The ethanol concentration was 70%;The Solid-liquid ratio was 1:20(g/mL);40 min for ultrasonic extraction;The ultrasonic power was 350 W;100 mesh size for particle size.The yield of fat-soluble was 30.38%by these extraction conditions.Basis on the single factor test,the optimized process parameters in orthogonal optimization test were determined by response surface methodology of Box-Behnken model:The ethanol concentration was 70%;The Solid-liquid ratio was 1:17.5(g/mL);41 min for ultrasonic extraction;Sonication power was 415 W;Raw material particle size was 100 mesh.The contents of CA and carnosol were 12.25%and 14.06%,respectively under HPLC determination by orthogonal optimization method.(2).The in vitro antioxidant activities of the lipid-soluble extract of rosemary and three commonly used synthetic antioxidants,TBHQ,BHT and BHA,were compared for their ability to scavenge and reduce DPPH· and ABTS·+ free radicals.The results showed:the ability of scavenging free radicals was ranked as following:TBHQ>rosemary fat-soluble extract>BHT>BHA;While the deoxidizing ability of the fat-soluble extract of rosemary was weaker than the other three chemical synthetic antioxidants,but still had some effects.(3)The effects of the five natural antioxidants(Rosemary,tea polyphenols,licorice extract,VC and VE)and the three chemical synthesized antioxidants(TBHQ,BHA and BHT)on the oxidative stability of rapeseed oil were investigated by the Rancimat method by tested their oxidation-induced stability.The results showed as follows:TBHQ>rosemary fat-soluble antioxidants>tea polyphenols>VE>licorice extract.(4)Orthogonal test were used to optimize the experiments,and the five natural antioxidants,including rosemary fat-soluble extract,tea polyphenol,licorice extract,VC and VE,were selected for the antioxidant compounds.By tested their oxidation-induced stability,the optimal compounding ratio was obtained.Rosemary fat-soluble antioxidant was 0.07%;Tea polyphenol was 0.06%;VE was 0.03%and licorice extract was 0.06%.Using this optimal compounding ratio,the oxidation induction time was 17.86 h;and calculated on the Arrhenius formula,the theoretical shelf life of rapeseed oil was 3.19 years at room temperature of 25℃.(5)The effects of the optimized compounded antioxidants(0.07%rosemary,0.06%tea polyphenols,0.06%licorice extract and 0.03%VE),rosemary fat-soluble extract,TBHQ,BHA and BHT on the quality of rapeseed oil were compared using peroxide value and fatty acids as measurement indicators.The results showed that the optimized compounded antioxidants have a good stability and antioxidant properties.