Complex enzyme hydrolysis releases antioxidative phenolics from rice bran

Area of Science:

• Food Science
• Biochemistry
• Nutraceuticals

Background:

• Rice bran is a rich source of bioactive compounds, including phenolics.
• Processing methods influence the extraction and bioavailability of these compounds.
• Enhancing antioxidant properties of rice bran is crucial for its utilization in functional foods.

Purpose of the Study:

• To analyze the phenolic profiles and antioxidant activity of rice bran.
• To evaluate the impact of gelatinization, liquefaction, and complex enzyme hydrolysis on phenolic release.
• To identify key phenolic compounds and their forms (free vs. conjugated) after enzymatic processing.

Main Methods:

• Successive treatment of rice bran using gelatinization, liquefaction, and complex enzyme hydrolysis.
• Quantification of total phenolics, flavonoids, and antioxidant activity using Ferric Reducing Antioxidant Power (FRAP) and Oxygen Radical Absorbance Capacity (ORAC) assays.
• Analysis of individual phenolic compounds, including ferulic acid, protocatechuic acid, and quercetin.

Main Results:

• Complex enzyme hydrolysis significantly increased total phenolics (46.24%) and flavonoids (79.13%) compared to gelatinization alone.
• Antioxidant activity, measured by FRAP and ORAC, was substantially enhanced by complex enzyme hydrolysis (159.14% and 41.98%, respectively).
• Ferulic acid, protocatechuic acid, and quercetin were among the most released phenolics, predominantly in soluble conjugate forms.

Conclusions:

• Complex enzyme hydrolysis is an effective method for releasing a wide range of phenolics from rice bran.
• The increased phenolic content directly correlates with enhanced antioxidant activity in rice bran extracts.
• This study provides valuable insights for developing phenolic-rich functional beverages from rice bran.