Response surface methodology for the extraction of bioactive compound from black glutinous rice

P Penjumras,K Panngom,W Panjan,I Wattananapakasem,J Sornsakdanuphap

doi:10.26656/fr.2017.4(s6).028

Abstract

This study was aimed at the extraction of total phenolic compounds, as well as, the antioxidant activity of black glutinous rice (Oryza sativa L.). Black glutinous rice of three varieties consists of Leum Pua, Doi Saket, and Phayao were extracted using citric acid solvent. The influences of temperature, time and pH value on total phenolic content and antioxidant activity (percentage of inhibition of DPPH free radical) were investigated. A central composite design was employed to determine the optimum extraction condition to obtain the highest total phenolic content and antioxidant activity. The regression models of total phenolic content were significant (p0.05) and determination coefficients values were 0.8028, 0.8089, and 0.8603 of Leum Pua, Doi Saket, and Phayao, respectively. The regression models of DPPH inhibition were significant (p0.05) and determination coefficients values were 0.8084, 0.8928, and 0.8243 of Leum Pua, Doi Saket, and Phayao, respectively. The selected optimum conditions were 72°C, 91 mins at pH 1.44 for Leum Pua, 72.5°C, 83 mins at pH 1.39 for Doi Saket, and 66.3°C, 75 mins at pH 1.32 for Phayao. Under the optimum condition, total phenolic content and percentage of inhibition of DPPH free radical of extract from Leum Pua, Doi Saket and Phayao were 0.3814 mg GAE g-1 DW with 89.36%, 0.2607 mg GAE g-1 DW with 73.33%, and 0.2617 mg GAE g1 DW with 75.27%, respectively. The results showed that the total phenolic content of the extract indicated a highly positive correlation with antioxidant activity.

Highlights

Pigmented rice varieties contain a higher amount of phenolic compound; cyanidin -3-glucoside, malvidin-3-glucose, and peonidin-3glucoside compare to white rice (Pedro et al, 2016; Bae et al, 2017; Seekhaw et al, 2018)
The extraction temperature showed the positive effect on total phenolic content of the rice extracted from three varieties but provided negative effect on antioxidant activity of the extract of Phayao
The extraction time presented the positive effect on total phenolic content but a negative effect on antioxidant of the extract of Leum Pua and Doi Saket

Summary

Introduction

Rice (Oryza sativa L.) is being consumed as a staple food for many countries nearly half of the world population, in the Asian country. Ethanol and organic acids such as citric acid and acetic acid are desirable because they are less toxic than methanol and hydrochloric acid (EscribanoBailón et al, 2004; Phetpornpaisan et al, 2014; Shao et al, 2014) The factor such as type of solvent, extraction temperature, extraction time and the ratio of sample to solvent has a significant influence on the extraction process, the combination of these factors and determination of optimal conditions are important in order to achieve a suitable yield of phenolic compound and its property. To overcome this limitation, the use of Penjumras et al / Food Research 4 The optimized conditions of the independent variables to maximize values were reported in this research

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Conclusion