Alkaline Extraction of Ferulic Acid from Wheat Bran – Process Optimization and General Yield Considerations

Wheat plays a key role in the EU economy, mainly in the food sector. However, the wheat value chain also generates large amounts of by-products, such as bran. From a circular economy perspective, it is essential to valorise wheat bran. Of particular interest is the possibility of recovering valuable compounds like ferulic acid (FA) which shows considerable promise. Different protocols have been tested for FA extraction, and alkaline hydrolysis is generally considered capable of achieving nearly 100% yield of FA from wheat or bran. The present study demonstrates that even current alkaline hydrolysis protocol of wheat bran can be further optimized to increase FA extraction yields. Starting from a generally accepted alkaline hydrolysis FA extraction protocol, several process parameters were modified in different laboratory trials, including potential pre-treatments, solid/liquid ratio, NaOH concentration, incubation time and temperature. The most effective protocol was then up-scaled in pilot plant and validated. The resulting FA yields varied depending on the scale of extraction. The findings of this study are valuable for the future valorisation of wheat bran and can be exported to other similar agro-industrial by-products. Additionally, these results open to the reconsideration of how the total content of FA in wheat (and more broadly, the extractable phytochemicals from plants), is evaluated. Conclusions, suggest that expressing yields as percentage may lead to overestimates, while a more accurate representation would be to express yields respect to the feedstock weight (e.g., mg FA/kg bran).