Wageningen University, Netherlands
Recently there is a great interest in the recovery, separation and purification of natural bioactive compounds from plant foods and especially polyphenols, due to their proven antioxidant, anticancer activity and other health benefits. Rapeseed and sunflower seeds are considered rich sources of polyphenols and they are currently underexploited. After oil extraction, the defatted meals remaining tend to be used as cattle feed, despite their verified content in valuable phenolic acids such as sinapic, chlorogenic and caffeic acid. Moreover, especially due to their high protein content, there is a great interest in their fractionation for protein acquisition. However, the recovery procedure of polyphenols can affect the fate of the protein and remaining components, either due to intense processing or interactions occurring between the polyphenols and proteins specifically. With the use of organic solvents and high temperatures for the extraction of polyphenols, denaturation of the remaining proteins in the matrix can occur. Moreover, alkaline treatment can lead to polyphenol-protein complexation affecting both the extractability and the functionality of both polyphenols and proteins. These are the main reasons why sunflower and rapeseed protein fractionation techniques are currently under investigation.
The recovery procedure of polyphenols is important for the viability of biorefineries handling protein-rich multi-components streams. We expect with the use of milder extraction methods for the recovery of polyphenols, the modification on the macromolecules can be controlled or avoided. This will create new opportunities for the valorization of ingredients like oilseed meals, out of which both polyphenols and proteins can be separated, or let co-exist in the food streams leading to unexplored nutritional benefits.