Extraction method of total flavonoids from barley grains based on response surface methodology and its antioxidant activity

【Objective】To provide scientific reference for the research and development of flavonoids in barley seeds by using response surface methodology to optimize the extraction process of total flavonoids from barley seeds and analyzing their antioxidant activity.【Method】By conducting a single factor experiment to investigate the extraction time of different oscillation methods (ordinary oscillator oscillation and ultrasonic oscillation),the effects of different types of extraction solutions (methanol and ethanol) and their concentrations,as well as different solid-liquid ratios on the extraction of total flavonoids from barley seeds,the main influencing factors were determined.Then,the response surface methodology was used to optimize the extraction process of total flavonoids from barley seeds,and 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH) was used to evaluate the antioxidant activity of barley flavonoids.【Result】The single factor experiment selected ethanol as the extraction solution and used ultrasonic extraction.The established regression model:Y=5968.42+1148.42A-80.73B+84.16C+312.09AB-39.94BC-955.41A²-790.56B²-316.62C²(Y was the total flavonoid extraction amount,A was the volume fraction of ethanol,B was the solid-liquid ratio,and C was the ultrasonic extraction time).Among them,ethanol volume fraction had extremely significant effect(P<0.01),solid-liquid had the least effect.The interaction between the two factors had no significant effect on the extraction of total flavonoids from barley grains(P>0.05).The optimized extraction process conditions for total flavonoids from barley seeds were as follows:ethanol volume fraction of 56%,solid-liquid ratio of 1∶20,ultrasonic extraction time of 89 min.Under these conditions,a total flavonoid extraction amount of 6201.0µg/g from barley seeds was obtained.The antioxidant results indicated that barley flavonoids had certain scavenging ability against DPPH free radicals.In the range of 50-300µg/mL,the scavenging ability of barley flavonoids against DPPH free radicals was correlated with their concentration.【Conclusion】The extraction process of total flavonoids from barley seeds optimized by response surface methodology can effectively improve the extraction efficiency,shorten the extraction time,and the extracted barley flavonoids have strong antioxidant activity.