Benefits and drawbacks on the incorporation of grape seeds into bakery products: Is it worth it?

Grape is the third most produced fruit in the world, owing to its taste and its use as raw material for winemaking. Due to this fact, large volumes of waste biomass are generated as a result of grape juice and wine production, mainly grape seeds (GS) and peels. In recent decades, scientific research has highlighted the high content of polyphenols in GS, especially condensed tannins, and resveratrol. These compounds have been correlated to various potential benefits to human health, such as antioxidant, hypoglycemic, hypolipidemic or anti-inflammatory, among others. GS polyphenols may be incorporated into functional foods, especially as flour in wheat-based bakery products, appears to be an attractive option. Two strategies may be followed. By one hand, the incorporation of GS flour increases fiber, mineral and protein content of bakery products, as well as their hardness and phenolic content. However, it seems that consumers may accept up to 10% of GS flour since higher doses strongly diminish the organoleptic properties of the product. The other alternative involves the incorporation of polyphenol-rich GS extracts into the bakery formulations which would carry their beneficial bioactivities to final product. Nonetheless, this method is more laborious since it requires a prior chemical extraction of GS, and the control and addition of a safe, food-grade extract into the flour. Both strategies have been reported to increase phenolic content and antioxidant capacity of bakery products. The direct incorporation of GS flour is affordable for industries while the incorporation of polyphenol-rich extracts leads to the development of functional products with additional beneficial properties. This work discusses the benefits and potential hurdles of functional bakery products with incorporated GS flour and extracts based on up-to-date evidence.