Optimization of Convection Method on Phenolic Antioxidants and Antioxidant Activity of Hordeum Vulgare (Barley)

Wong, Wei Jian (2021) Optimization of Convection Method on Phenolic Antioxidants and Antioxidant Activity of Hordeum Vulgare (Barley). Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The main objective of this project was to investigate the effects of extraction conditions on the extraction yield, total phenolic content(TPC), total flavonoid content (TFC) and antioxidant activity (free radical scavenging activity) of barley (Hordeum vulgare L.) extract. The correlation among the extraction yield, phenolic content and antioxidant activity of the barley extract under different extraction conditions was studied too. Three process variables, namely extraction time (1-3 h), ethanol concentration (0-100%) and temperature (50-70oC) were varied, and the extracted antioxidants were freeze dried overnight for use of analyses. The extraction yield, phenolic and flavonoid contents and DPPH radical scavenging antioxidant activity of the barley extract were analysed. All variables were found to significantly (p<0.05) affect all the responses. The extraction conditions which gave the highest extraction yield was 70oC, 3 h extraction time and 100% ethanol as a solvent with the value of 20.59 ± 1.61%. On the other hand, the extraction conditions for highest total phenolic content (2.824 ± 0.226 mg GAE/g), total flavonoid content (48.940 ± 0.431 mg QE/g) and antioxidant activity (9.445 ± 0.490 mg AEAC/g) were 50oC, 3 h extraction time and 100% ethanol. In short, it has been suggested that a longer extraction time of 3 h should combine with moderately extraction temperature (50oC) using 100% ethanol to give a higher total phenolic content, total flavonoid content and high free radical scavenging activity. However, the extraction conditions should be well monitored as the elevated temperature will cause degradation of phenolic antioxidant, leading to lesser expression in antioxidant activity of the barley extract.