Dynamic High-pressure Microfluidization-assisted Method for Extraction of Total Flavonoids from Cyperus esculentus L. Leaves and Application in Cookies
The optimum conditions for extraction of flavonoids from Cyperus esculentus L. (CE L.) leaves by dynamic high-pressure microfluidization-assisted method (DHPM) was determined through single factor and orthogonal experiments. The yield of flavonoids and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging rate were used as indices. The effect of DHPM on the structure and composition of total flavonoids from CE L. leaves was preliminarily analyzed by ultraviolet-visible and infrared spectral analyses and liquid chromatography–mass spectrometry (LC-MS). At the same time, peroxide value (POV) and acid value (AV) were used as indicators to investigate the effect of total flavonoids from CE L. leaves on the storability of cookies. The results showed the following conditions of DHPM as optimum: microfluidization pressure=120 MPa; extraction temperature=80 ℃; ethanol concentration=80%; extraction time=90 min. Under these optimal extraction conditions, the yield of flavonoids was 1.46% and the half-maximal inhibitory concentration (IC50) value for DPPH scavenging activity was 0.17±0.02 mg/mL. The DHPM-assisted extraction enhanced the yield and antioxidant activities of total flavonoids from CE L. leaves. The results of LC-MS analysis indicated that the treatment of DHPM did not change the composition of total flavonoids from CE L. leaves; however, the ratio of some constituents were altered. The results of POV and AV showed that total flavonoids from CE L. leaves could serve as natural antioxidants for cookie production.
