Effects of debranning on the distribution of pentosans and relationships to phenolic content and antioxidant activity of wheat pearling fractions

Pentosans represent the major dietary fiber constituent in wheat and the predominant source of antioxidant activity (AOA) whose nature is closely associated with the phenolic compound ferulic acid. Incremental debranning was used to determine effects on pentosan content and AOA of pearled fractions. Four cultivar samples were debranned to obtain pearling fractions, each equivalent to 5% of initial sample weight up to 60%. Total pentosans (TP), water-extractable pentosans (WEP), total phenolic content (TPC) and AOA were determined. There were significant differences among genotypes in response to debranning although trends were consistent. WEP was maximized in the 10% debranning fraction which likely maximized aleurone content. TP content was highest in the initial 5% fraction and progressively declined in successive fractions. Relationships between pentosan composition and AOA followed different trends. TP and water-unextractable pentosans (WUP) were highly correlated to TPC (R2 = 0.84) and AOA (R2 = 0.88) for the 10-25% debranning fractions. No significant correlations were found between TPC and AOA with WEP. Results indicated that debranning wheat to recover material between the initial 5% pearling fraction and the next 5% was effective to produce bran fractions for functional food or nutraceutical purposes, highly enriched in dietary fiber and AOA.

► Debranning wheat can produce fractions with high fiber content and antioxidant activity. ► Wheat debranning needs to be precise to optimize content of functional components. ► Wheat pentosans, phenolic content and antioxidant activity are highly correlated. ► Pentosans represent the major source of wheat phenolics and antioxidant activity. ► Patterns of variation of water-soluble and insoluble pentosans are different.