THE FORMATION OF FERULIC ACID FROM GAMMA-ORYZANOL HYDROLYSIS UNDER ALKALINE CONDITION USING ULTRASONIC IRRADIATION

Abstract

  In this study, we investigated the formation of ferulic acid, one of potentialantioxidants, medicines, and cosmetics, by the hydrolysis of γ-oryzanol contained inby-products of rice bran oil processing. Using a base-catalysed reaction, thehydrolysis of γ-oryzanol was examined, and the experiments were conducted withvarious conditions of catalyst amounts, temperature dependency, and ultrasonicfrequencies. After 3 hours of conventional heating, 45% and 73% yield of ferulicacid was obtained using a 10:1 (wt/wt) ratio of KOH/ γ-oryzanol at the temperatureof 60, and 75 C, respectively. The different frequencies (26, 78 and 130 kHz) wereinvestigated to examine effect of ultrasound on yield of hydrolysis. Among them, theuses of 78 and 130 kHz irradiation accelerated the formation of ferulic acid up to 1.6- fold times greater than that by the conventional heating at 60 ºC, and that yield wasincreased only 1.2 times when using lower frequency (26 kHz) at same temperature.Utilizing ultrasonic irradiation (78 and 130 kHz) at 75 C, the hydrolysis of γ-oryzanol proceeded quantitatively, and the yield of ferulic acid was achieved morethan 90%.

Keywords: ferulic acid, γ-oryzanol, ultrasound, base-catalysed reaction, hydrolysis