Assessing the influence of extrusion processing on functional properties and phytochemical profiles in diverse rice bran varieties

Background and Objectives

The aims of this study were to assess the functional and phytochemical characteristics, as well as the antioxidant properties, of bran from five distinct rice varieties. Additionally, it evaluated the impact of extrusion cooking on the composition and quantity of individual phytochemicals in both free and bound states in the bran of these varieties.

Findings

The functional properties and phytochemical profiles of raw and extruded rice bran from different rice varieties differed significantly. The extrusion process significantly influenced the color, protein solubility, foaming properties, polyphenolics, and amino acid composition of rice bran. Total phenolics ranged from 3.18 to 4.80 mg GAE/g, increased by 12.6%–17% postextrusion. Similarly, total flavonoid content ranged from 15.22 to 17.37 mg RTE/100 g, with a 30%–33% increase after extrusion cooking. Throughout the extrusion process, a rise in the concentration of free phenolics accompanied by a decrease in the concentration of bound phenolics was observed.

Conclusion

The study revealed the impact of extrusion cooking on the distribution of total phytochemicals, particularly phenolics and flavonoids, and the levels of antioxidant activity in free and bound phenolics, as well as amino acid composition and functional properties. The extrusion cooking increased levels of free phenolics and 2,2-diphenyl-1-picrylhydrazyl activity, while bound forms decreased. Extrusion cooking variably impacted the functionality and phytochemical content of bran from different rice varieties, thus influencing their likely applications.

Significance and Novelty

This study established the foundation for producing food products using extruded rice bran, offering health benefits and meeting the growing demand in the functional food sector.